2013 Microchip Technology Inc. DS01569A-page 1
Datasheet
PRODUCT FEATURES
CAP1296
6-Channel Capacitive Touch Sensor with
Proximity Detection & Signal Guard
General Description
The CAP1296 which incorporates RightTouch® technology,
is a multiple channel capacitive touch sensor. It contains six
(6) individual capacitive touch sensor inputs with
programmable sensitivity for use in touch sensor
applications. Each sensor input is calibrated to compensate
for system parasitic capacitance and automatically
recalibrated to compensate for gradual environmental
changes.
In addition, the CAP1296 can be configured to detect
proximity on one or more channels with an optional signal
guard to reduce noise sensitivity and to isolate the proximity
antenna from nearby conductive surfaces that would
otherwise attenuate the e-field.
The CAP1296 includes Multiple Pattern Touch recognition
that allows the user to select a specific set of buttons to be
touched simultaneously. If this pattern is detected, a status
bit is set and an interrupt is generated.
The CAP1296 has Active and Standby states, each with its
own sensor input configuration controls. The Combo state
allows a combination of sensor input controls to be used
which enables one or more sensor inputs to operate as
buttons while another sensor input is operating as a
proximity detector. Power consumption in the Standby and
Combo states is dependent on the number of sensor inputs
enabled as well as averaging, sampling time, and cycle
time. Deep Sleep is the lowest power state available,
drawing 5µA (typical) of current. In this state, no sensor
inputs are active, and communications will wake the device.
Applications
Desktop and Notebook PCs
LCD Monitors
Consumer Electronics
Appliances
Features
Six (6) Capacitive Touch Sensor Inputs
— Programmable sensitivity
— Automatic recalibration
— Calibrates for parasitic capacitance
— Individual thresholds for each button
Proximity Detection
Signal Guard
— Isolates the proximity antenna from attenuation
— Reduces system noise sensitivity effects on inputs
Multiple Button Pattern Detection
Power Button Support
Press and Hold Feature for Volume-like Applications
3.3V or 5V Supply
Analog Filtering for System Noise Sources
RF Detection and Avoidance Filters
Digital EMI Blocker
8kV ESD Rating on All Pins (HBM)
Low Power Operation
— 5µA quiescent current in Deep Sleep
— 50µA quiescent current in Standby (1 sensor input
monitored)
— Samples one or more channels in Standby
SMBus / I2C Compliant Communication Interface
Available in a 10-pin 3mm x 3mm DFN RoHS compliant
package
Block Diagram
SMBus
Protocol
VDD GND
Capacitive Touch S ensing
Algorithm
CS1 CS2 CS4 CS5
SMCLK
SMDATA
ALERT#
CS6
CS3 /
SG
Reel size is 4,000 pieces for 10-pin DFN
This product meets the halogen maximum concentration values per IEC61249-2-21
ORDERING
NUMBER PACKAGE FEATURES
CAP1296-1-AIA-TR 10-pin DFN 3mm x 3mm
(RoHS compliant) Six capacitive touch sensor inputs, SMBus interface,
SMBus address 0101_000(r/w). Proximity and signal
guard.
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 2 2013 Microchip Technology Inc.
Ordering Information:
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 3
Table of Contents
Chapter 1 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 3 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 System Management Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1 SMBus Start Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.2 SMBus Address and RD / WR Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.3 SMBus Data Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.4 SMBus ACK and NACK Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.5 SMBus Stop Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.6 SMBus Timeout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.7 SMBus and I2C Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 SMBus Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3.1 SMBus Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.2 SMBus Read Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.3 SMBus Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3.4 SMBus Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.4 I2C Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.1 Block Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.2 Block Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 4 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 Power States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Capacitive Touch Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.1 Capacitive Touch Sensing Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.1.1 Active State Sensing Settings........................................................................................20
4.3.1.2 Standby State Sensing Settings .................... ... ................ ... ... .... ................ ... ... ... .... ......20
4.3.1.3 Combo State Sensing Settings......................................................................................21
4.3.2 Sensing Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 Sensor Input Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4.1 Automatic Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.2 Negative Delta Count Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.3 Delayed Recalibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.5 Proximity Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.5.1 Signal Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.6 Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.7 Multiple Touch Pattern Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8 Noise Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.1 Low Frequency Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.2 RF Noise Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.8.3 Noise Status and Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.9 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.9.1 ALERT# Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.9.2 Capacitive Sensor Input Interrupt Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.9.3 Interrupts for the Power Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.4 Interrupts for Multiple Touch Pattern Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.9.5 Interrupts for Sensor Input Calibration Failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 4 2013 Microchip Technology Inc.
Chapter 5 Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5.2 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.2.1 General Status - 02h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.2.2 Sensor Input Status - 03h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.3 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.4 Sensor Input De lta Co unt Reg i st er s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.5 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.6 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.6.1 Configuration - 20h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.6.2 Configuration 2 - 44h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.7 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.8 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.9 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.10 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.11 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.12 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.13 Repeat Rate Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.14 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.15 Multiple Touch Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.16 Multiple Touch Pattern Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.17 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.18 Base Count Out of Limit Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.19 Recalibration Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.20 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
5.21 Sensor Input Noise T hr es ho ld Re gist er . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.22 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.23 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.24 Standby Sensitivity Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.25 Standby Threshold Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.26 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.27 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.28 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.29 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.30 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.31 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.32 Manufacturer ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.33 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Chapter 6 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.1 CAP1296 Package Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.2 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Appendix ADevice Delta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
A.1 Delta from CAP1106-1 to CAP1296-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 5
List of Figures
Figure 1.1 CAP1296-1 Pin Diagram (10-Pin 3 x 3 mm DFN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 3.1 SMBus Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 4.1 System Diagram for CAP1296 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 4.2 POR and PORR With Slow Rising VDD and BOR with Falling VDD . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 4.3 Signal Guard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 6.1 CAP1296 Package Drawing - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 6.2 CAP1296 Package Dimensions - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 6.3 CAP1296 PCB Land Pattern and Stencil - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . 61
Figure 6.4 CAP1296 PCB Detail A - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 6.5 CAP1296 PCB Detail B - 10-Pin DFN 3mm x 3mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Figure 6.6 CAP1296 Land Dimensions - 10-Pin DFN 3mm x 3mm. . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Figure 6.7 CAP1296-1 Package Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 6 2013 Microchip Technology Inc.
List of Tables
Table 1.1 Pin Description for CAP1296 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 1.2 Pin Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 2.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 2.2 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 3.1 Protocol Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 3.2 Write Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.3 Read Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.4 Send Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.5 Receive Byte Protocol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3.6 Block Read Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 3.7 Block Write Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 4.1 Ideal Base Counts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 5.1 Register Set in Hexadecimal Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 5.2 Main Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 5.3 Power State Bit Overrides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 5.4 GAIN and C_GAIN Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 5.5 Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 5.6 Noise Flag Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 5.7 Sensor Input Delta Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 5.8 Sensitivity Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 5.9 DELTA_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 5.10 BASE_SHIFT Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 5.11 Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 5.12 Sensor Input Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.13 Sensor Input Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.14 MAX_DUR Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 5.15 RPT_RATE Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 5.16 Sensor Input Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 5.17 M_PRESS Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 5.18 Averaging and Sampling Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5.19 AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5.20 SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.21 CYCLE_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.22 Calibration Activate and Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 5.23 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table 5.24 Repeat Rate Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 5.25 Signal Guard Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 5.26 Multiple Touch Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 5.27 B_MULT_T Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 5.28 Multiple Touch Pattern Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 5.29 MTP_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 5.30 Multiple Touch Pattern Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 5.31 Base Count Out of Limit Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 5.32 Recalibration Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 5.33 NEG_DELTA_CNT Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 5.34 CAL_CFG Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 5.35 Sensor Input Threshold Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 5.36 Sensor Input Noise Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.37 CSx_BN_TH Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.38 Standby Channel Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 5.39 Standby Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Table 5.40 STBY_AVG Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
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Table 5.41 STBY_SAMP_TIME Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5.42 STBY_CY_TIME Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 5.43 Standby Sensitivity Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.44 STBY_SENSE Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.45 Standby Threshold Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 5.46 Sensor Input Base Count Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 5.47 Power Button Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 5.48 PWR_BTN Bit Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 5.49 Power Button Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 5.50 Power Button Time Bits Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 5.51 Sensor Input Calibration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 5.52 Calibration Sensitivity Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.53 CALSENX Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.54 Product ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.55 Vendor ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 5.56 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table A.1 Register Delta. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 6.1 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
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Chapter 1 Pin Description
Figure 1.1 CAP1296-1 Pin Diagram (10-Pin 3 x 3 mm DFN)
Table 1.1 Pin Description for CAP1296
PIN # PIN NAME PIN FUNCTION PIN TYPE UNUSED
CONNECTION
1 CS1 Capacitive Touch Sensor Input 1 AIO Connect to
Ground
2ALERT#
ALERT# - Active low alert / interrupt output for
SMBus alert - requires pull-up resistor (default) OD Connect to
Ground
3SMDATA
SMDATA - Bi-directional, open-drain SMBus or
I2C data - requires pull-up resistor DIOD n/a
4SMCLK
SMCLK - SMBus or I2C clock input - requires
pull-up resistor DI n/a
5 VDD Positive Power supply Power n/a
6 CS6 Capacitive Touch Sensor Input 6 AIO Connect to
Ground
7 CS5 Capacitive Touch Sensor Input 5 AIO Connect to
Ground
8 CS4 Capacitive Touch Sensor Input 4 AIO Connect to
Ground
9 CS3 / SG CS3 - Capacitive Touch Sensor Input 3 AIO Connect to
Ground
SG - Signal guard output AIO Leave Open
10 CS2 Capacitive Touch Sensor Input 2 AIO Connect to
Ground
Bottom
Pad GND Ground Power n/a
CS3 / SG
CS2
1
2
3
4
5
CS4
CS1
ALERT#
SMDATA
VDD
SMCLK CS5
CS6
GND
10
9
8
7
6
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APPLICATION NOTE: All digital pins are 5V tolerant pins.
The pin types are described in Table 1.2.
Table 1.2 Pin Types
PIN TYPE DESCRIPTION
Power This pin is used to supply power or ground to the device.
DI Digital Input - This pin is used as a digital input. This pin is 5V tolerant.
AIO Analog Input / Output - This pin is used as an I/O for analog signals.
DIOD Digital Input / Open Drain Output - This pin is used as a digital I/O. When it is used as an
output, it is open drain and requires a pull-up resistor. This pin is 5V tolerant.
OD Open Drain Digital Output - This pin is used as a digital output. It is open drain and requires
a pull-up resistor. This pin is 5V tolerant.
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Chapter 2 Electrical Specifications
Note 2.1 Stresses above th ose listed could cause permanent damage to the device. This is a stress
rating only and functional operation of the device at any other condition above those
indicated in the operation sections of this specification is not implied.
Note 2.2 For the 5V tolerant pins that have a pull-up resistor, the voltage difference between
V5VT_PIN and VDD must never exceed 3.6V.
Note 2.3 The Package Power Dissipation specification assumes a recommended thermal via design
consisting of a 2x3 matrix of 0.3mm (12mil) vias at 0.9mm pitch connected to the ground
plane with a 1.6 x 2.3mm thermal landing.
Note 2.4 Junction to Ambi ent (θJA) is dependent on the design of the thermal vias. Without thermal
vias and a thermal landing, the θJA will be higher.
Table 2.1 Absolute Maximum Ratings
Voltage on VDD pin -0.3 to 6.5 V
Voltage on CS pins to GND -0.3 to 4.0 V
Voltage on 5V tolerant pins (V5VT_PIN) -0.3 to 5.5 V
Voltage on 5V tolerant pins (|V5VT_PIN - VDD|) (see Note 2.2)0 to 3.6 V
Input current to any pin except VDD +10 mA
Output short circuit current Continuous N/A
Package Power Dissipation up to TA = 85°C for 10-pin DFN
(see Note 2.3)0.5 W
Junction to Ambient (θJA) (see Note 2.4)78 °C/W
Operating Ambient Temperature Range -40 to 125 °C
Storage Temperature Range -55 to 150 °C
ESD Rating, All Pins, HBM 8000 V
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Table 2.2 Electrical Specifications
VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
DC POWER
Supply Voltage VDD 3.0 5.5 V
Supply Current ISTBY_DEF 120 170 µA Standby state active
1 sensor input monitored
Default conditions (8 avg, 70ms
cycle time)
ISTBY_LP 50 µA Standby state active
1 sensor input monitored
1 avg, 140ms cycle time
IDSLEEP_3V 5TBDµA Deep Sleep state active
No communications
TA < 40°C
3.135 < VDD < 3.465V
IDSLEEP_5V TBD TBD µA Deep Sleep state active
No communications
TA < 40°C
VDD = 5V
IDD 500 750 µA Capacitive Sensing Active
signal guard disabled
CAPACITIVE TOUCH SENSOR INPUTS
Maximum Base
Capacitance CBASE 50 pF Pad untouched
Minimum Detectable
Capacitive Shift ΔCTOUCH 20 fF Pad touched - default conditions
Recommended Cap
Shift ΔCTOUCH 0.1 2 pF Pad touched - Not tested
Power Supply
Rejection PSR ±3 ±10 counts
/ V
Untouched Current Counts
Base Capacitance 5pF - 50pF
Negative Delta Counts disabled
Maximum sensitivity
All other parameters default
POWER-ON AND BROWN-OUT RESET (SEE Section 4.2, "Reset")
Power-On Reset
Voltage VPOR 1 1.3 V Pin States Defined
Power-On Reset
Release Voltage VPORR 2.85 V Rising VDD
Ensured by design
Brown-Out Reset VBOR 2.8 V Falling VDD
VDD Rise Rate
(ensures internal
POR signal) SVDD 0.05 V/ms 0 to 3V in 60ms
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Power-Up Timer
Period tPWRT 10 ms
Brown-Out Reset
Voltage Delay tBORDC 1µsV
DD = VBOR - 1
TIMING
Time to
Communications
Ready tCOMM_DLY 15 ms
Time to First
Conversion Ready tCONV_DLY 170 200 ms
I/O PINS
Output Low Voltage VOL 0.4 V ISINK_IO = 8mA
Output High Voltage VOH VDD -
0.4 VI
SOURCE_IO = 8mA
Input High Voltage VIH 2.0 V
Input Low Voltage VIL 0.8 V
Leakage Current ILEAK ±5 µA powered or unpowered
TA < 85°C
pull-up voltage < 3.6V if
unpowered
SG PIN
Capacitive Drive
Capability CBASE_SG 20 200 pF capacitance to ground
SMBUS TIMING
Input Capacitance CIN 5pF
Clock Frequency fSMB 10 400 kHz
Spike Suppression tSP 50 ns
Bus Free Time Stop
to Start tBUF 1.3 µs
Start Setup Time tSU:STA 0.6 µs
Star t Ho ld Tim e tHD:STA 0.6 µs
Stop Setup Time tSU:STO 0.6 µs
Data Hold Time tHD:DAT 0 µs When transmitting to the master
Data Hold Time tHD:DAT 0.3 µs When receiving from the master
Data Setup Time tSU:DAT 0.6 µs
Table 2.2 Electrical Specifications (continued)
VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
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Clock Low Period tLOW 1.3 µs
Clock High Period tHIGH 0.6 µs
Clock / Data Fall
Time tFALL 300 ns Min = 20+0.1CLOAD ns
Clock / Data Rise
Time tRISE 300 ns Min = 20+0.1CLOAD ns
Capacitive Load CLOAD 400 pF per bus line
Table 2.2 Electrical Specifications (continued)
VDD = 3V to 5.5V, TA = 0°C to 85°C, all Typical values at TA = 25°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
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Chapter 3 Communications
3.1 Communications
The CAP1296 communicates using the SMBus or I2C protocol.
3.2 System Management Bus
The CAP1296 communicates with a host controller, such as an MCHP SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timi ng diagram is shown in Figure 3.1. Stretching of the SMCLK signal is supported;
however, the CAP1296 will not stretch the clock signal.
3.2.1 SMBus Start Bit
The SMBus Start bit is defined as a transition of the SMBus Data line from a logic ‘1’ state to a logic
‘0’ state while the SMBus Clock line is in a logic ‘1’ state.
3.2.2 SMBus Address and RD / WR Bit
The SMBus Address Byte consists of the 7-bit client address followed by the RD / WR indicator bit. If
this RD / WR bit is a logic ‘0’, then the SMBus Ho st is writing data to the client device. If this RD / WR
bit is a logic ‘1’, then the SMBus Host is reading data from the client device.
The CAP1296 responds to SMBus address 0101_000(r/w).
3.2.3 SMBus Data Bytes
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
3.2.4 SMBus ACK and NACK Bits
The SMBus client will acknowledge all data bytes that it receives. This is done by the client device
pulling the SMBus Data line low after the 8th bit of each byte that is transmitted. This applies to both
the Write Byte and Block Write protocols.
The Host will NACK (not acknowledge) the last data byte to be received from the client by holding the
SMBus data line high after the 8th data bit has been sent. For the Block Read protocol, the Host will
ACK each data byte that it receives except the last data byte.
Figure 3.1 SMBus Timing Diagram
SMDATA
SMCLK
TBUF
PS S - Start Condition P - Stop C ondition PS
THIGH
TLOW THD:STA TSU:STO
THD:STA THD:DAT TSU:DAT TSU:STA
TFALL
TRISE
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3.2.5 SMBus Stop Bit
The SMBus Stop bit is defined as a transition of the SMBus Data line from a logic ‘0’ state to a logic
‘1’ state while the SMBus clock lin e is in a logic ‘1’ state. When the CAP1296 detects an SMBus Stop
bit and it has been communicating with the SMBus protocol, it will reset its client i nterface and prepare
to receive further communications.
3.2.6 SMBus Timeout
The CAP1296 includes an SMBus timeou t feature. Following a 30ms period of inactivity on the SMBus
where the SMCLK pin is held low, the device will timeout and reset the SMBus interface.
The timeout function defaults to disabled. It can be enabled by setting the TIMEOUT bit in the
Configuration register (see Section 5.6, "Configuration Registers").
3.2.7 SMBus and I2C Compatibility
The major differences between SMBus and I2C devices are highlighted here. For more information,
refer to the SMBus 2.0 specification.
1. CAP1296 supports I2C fast mode at 400kHz. This covers the SMBus max time of 100kHz.
2. Minimum frequency for SMBus communications is 10kHz.
3. The SMBus client protocol will reset if the clock is held low longer than 30ms (timeout condition).
This can be enabled in the CAP1296 by setting the TIMEOUT bit in the Configuration register. I2C
does not have a timeout.
4. The SMBus client protocol will reset if both the clock and the data line are high for longer than
200us (idle condition). This can be enabled in the CAP1296 by setting the TIMEOUT bit in the
Configuration register. I2C does not have an idle condition.
5. I2C devices do not suppo rt the Ale rt Respon se Addre ss functionality (wh ich is op ti onal for SMBus).
6. I2C devices support block read and write differently. I2C protocol allows for unlimited number of
bytes to be sent in either direction. The SMBus protocol requires that an additional data byte
indicating number of bytes to read / write is transmitted. The CAP1296 supports I2C formatting only.
3.3 SMBus Protocols
The CAP1296 is SMBus 2.0 compatible and supports Write Byte, Read Byte, Send Byte, and Receive
Byte as valid protocols as shown below.
All of the below protocols use the convention in Table 3.1.
Table 3.1 Protocol Format
DATA SENT
TO DEVICE DAT A SENT TO
THE HOST
Data sent Data sent
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3.3.1 SMBus Write Byte
The Write Byte is used to write one byte of data to a specific register as shown in Table 3.2.
3.3.2 SMBus Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown in Table 3.3.
3.3.3 SMBus Send Byte
The Send Byte protocol is used to set the internal address register pointer to the correct address
location. No data is transferred during the Send Byte protocol as shown in Table 3.4.
APPLICATION NOTE: The Send Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).
3.3.4 SMBus Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This is used for consecutive reads
of the same register as shown in Table 3.5.
APPLICATION NOTE: The Receive Byte protocol is not functional in Deep Sleep (i.e., DSLEEP bit is set).
Table 3.2 Wr ite Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK REGISTER
DATA ACK STOP
1 ->0 0101_000 0 0 XXh 0 XXh 0 0 -> 1
Table 3.3 Read Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK START CLIENT
ADDRESS RD ACK REGISTER
DATA NACK STOP
1->0 0101_000 0 0 XXh 0 1 ->0 0101_000 1 0 XXh 1 0 -> 1
Table 3.4 Send Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK STOP
1 -> 0 0101_000 0 0 XXh 0 0 -> 1
Table 3.5 Receive Byte Protocol
START SLAVE
ADDRESS RD ACK REGISTER DATA NACK STOP
1 -> 0 0101_000 1 0 XXh 1 0 -> 1
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3.4 I2C Protocols
The CAP1296 supports I2C Block Read and Block Write.
The protocols listed below use the convention in Table 3.1.
3.4.1 Block Read
The Block Read is used to read multiple data bytes from a group of contiguous registers as shown in
Table 3.6.
APPLICATION NOTE: When using the Block Read protocol, the internal address pointer will be automatically
incremented after every data byte is received. It will wrap from FFh to 00h.
3.4.2 Block Write
The Block Write is used to write multiple data bytes to a group of contiguous registers as shown in
Table 3.7.
APPLICATION NOTE: When using the Block Write protocol, the internal address pointer will be automatically
incremented after every data byte is received. It will wrap from FFh to 00h.
Table 3.6 Block Read Protocol
START S LAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK START SLAVE
ADDRESS RD ACK REGISTER
DATA
1->0 0101_000 0 0 XXh 0 1 ->0 0101_000 1 0 XXh
ACK REGISTER
DATA ACK REGISTER
DATA ACK REGISTER
DATA ACK . . . REGISTER
DATA NACK STOP
0 XXh 0 XXh 0 XXh 0 . . . XXh 1 0 -> 1
Table 3.7 Block Write Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK REGISTER
DATA ACK
1 ->0 0101_000 0 0 XXh 0 XXh 0
REGISTER
DATA ACK REGISTER
DATA ACK . . . REGISTER
DATA ACK STOP
XXh 0 XXh 0 . . . XXh 0 0 -> 1
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DS01569A-page 18 2013 Microchip Technology Inc.
Chapter 4 General Description
The CAP1296 is a multiple channel capacitive touch sensor. It contains six (6) individual capacitive
touch sensor inputs with programmable sensitivity for use in touch sensor applications. Each sensor
input is calibrated to compensate for system parasitic capacitance and automatically recalibrated to
compensate for gradual environmental changes.
In addition, the CAP1296 can be configured to detect proximity on one or more channels with an
optional signal guard to reduce noise sensitivity.
The CAP1296 includes Multiple Pattern Touch recognition that allows the user to select a specific set
of buttons to be touched simultaneously. If this pattern is detected, a status bit is set and an interrupt
is generated.
The CAP1296 has Active and Standby states, each with its own sensor input configuration controls.
The Combo state allows a combination of senso r input controls to be used which enables one or more
sensor inputs to operate as buttons while another sensor input is operating as a proximity detector.
Power consumption in the Standby and Combo states is dependent on the number of sensor inputs
enabled as well as averaging, sampling time, and cycle time. Deep Sleep is the lowest power state
available, drawing 5µA (typical) of current. In this state, no sensor inputs are active, and
communications will wake the device.
The device communicates with a host controller using SMBus / I2C. The host controller may poll the
device for updated information at an y time or it may configure the device to flag an interrupt whenever
a touch is detected on any sensor pad.
A typical system diagram is shown in Figure 4.1.
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4.1 Power States
The CAP1296 has 4 power states depending on the status of the STBY, COMBO, and DSLEEP bits
(see Section 5.1, "Main Control Register"). When the device transitions between power states,
previously detected touches (fo r ch ann els that are being d e-activated) a re clea red and the sensor i nput
status bits are reset.
1. Active - The normal mode of operation. The device is monitoring capacitive sensor inputs enabled
in the Active state (see Section 5.7, "Sensor Input Enable Register").
2. Standby - When the STBY bit is set, the device is monitoring the capacitive sensor inputs enabled
in the Standby state (see Section 5.22, "Standby Channel Register"). Interrupts can still be
generated based on the enabled channels. The device will still respond to communications
normally and can be returned to the Active state of operation by clearing the STBY bit. Power
consumption in this state is dependent on the number of sensor inputs enabled as well as
averaging, sampling time, and cycle time.
3. Combo - When the COMBO bit is set, the device is monitoring capacitive sensor inputs enabled
in the Active state as well as inputs enabled in the Standby state (hence the name “Combo”).
Interrupts can still be generated based on the enabled channels. The device will still respond to
communications normally and can be returned to the Active state of operation by clearing the
COMBO bit. Power consumption in this state is dependent on the nu mber of sensor inputs enabled
as well as averaging, sampling time, and cycle time.
Figure 4.1 System Diagram for CAP1296
CAP1296
CS4
SMDATA
SMCLK
Embedded
Controller
3.0V to 5.5V
ALERT#
CS5
CS6
CS2
CS1
Touch
Button
Touch
Button
Touch
Button
Proximity
Sensor
Touch
Button
SG*
VDDGND
* CS3 / SG is a multi- function pin. If not
using the signal gu ard shown here, CS3
can be another touc h button.
10kOhm
resistors 3. 0 V t o 5. 5V
1.0uF0.1uF
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DS01569A-page 20 2013 Microchip Technology Inc.
4. Deep Sleep - When the DSLEEP bit is set, the device is in its lowest power state. It is not
monitoring any capacitive sensor inputs. While in Deep Sleep, the CAP1296 can be awakened by
SMBus communications targeting the device. This will not cause the DSLEEP to be cleared so the
device will return to Deep Sleep once all communications have stopped. The device can be
returned to the Active state of operation by clearing the DSLEEP bit.
4.2 Reset
The Power-On Reset (POR) circuit holds the device in reset until VDD has reac hed an acceptable level,
Power-on Reset Release Voltage (VPORR), for minimum operation. The power-up timer (PWRT) is
used to extend the start-up period until all device operation conditions have been met. The power-up
timer starts after VDD reaches VPORR. POR and PORR with slow rising VDD is shown in Figure 4.2.
The Brown-Out Reset (BOR) circui t holds the device in reset when V DD falls to a minimum level, VBOR
for longer than the BOR reset delay (tBORDC). After a BOR, when VDD rises above VPORR, the power-
up timer is started again and must finish before reset is released, as shown in Figure 4.2.
4.3 Capacitive Touch Sensing
The CAP1296 contains six (6) independent capacitive touch sensor inputs. Each sensor input has
dynamic range to detect a change of capacitance due to a touch. Additionally, each sensor input can
be configured to be automatically and routinely recalibrated.
4.3.1 Capacitive Touch Sensing Settings
Controls for managing capacitive touch sensor inputs are determined by the power state.
4.3.1.1 Active State Sensing Settings
The Active state is used for normal operation. Sensor inputs being monitored are determined by the
Sensor Input Enable Register (see Section 5.7, "Sensor Input Enable Register"). Sensitivity is
controlled by the Sensitivity Control Register (see Section 5.5, "Sensitivity Control Register").
Averaging, sample time, and cycle time are controlled by the Averaging and Sampling Configuration
Register (see Section 5.10, "Averaging and Sa mpling Configura tion Register" ). Each channel can have
a separate touch detection threshold, as defined in the Sensor Input Threshold registers (see Section
5.20, "Sensor Input Threshold Registers").
4.3.1.2 Standby State Sensing Settings
The Standby state is used for standby operation. In gen eral, fewer sensor inputs are enabled, and they
are programmed to have more sensitivity. Sensor inputs being monitored are determined by the
Standby Channel Register (see Section 5.22, "Standby Channel Register"). Sensitivity is controlled by
Figure 4.2 POR and PORR With Slow Rising VDD and BOR with Falling VDD
VDD
VBOR
TPWRT
GND
Undefined
SYSRST
VPOR
VPORR
TBORDC TPWRT
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the Standby Sensitivity Register (see Section 5.24, "Standby Sensitivity Register"). Averaging, sample
time, and cycle time are controlled by the Averaging and Sampling Con figuration Register (see Section
5.23, "Standby Configuration Register"). There is one touch detection threshold, which applies to all
sensors enabled in Standby, as defined in the Standby Threshold Register (see Secti on 5.25, "Standby
Threshold Register").
4.3.1.3 Combo State Sensing Settings
The Combo state is used when a combination of proximity detection and normal button operation is
required. When the COMBO bit is set, the sensing cycle includes sensor inputs enabled in the Active
state as well as sensor inputs enabled in the Standby state. Sensor inputs enabled in the Active state
will use the Active settings described in Section 4.3.1.1, "Active State Sensing Settings" . Sensor inputs
enabled in the Standby state will use the Standby settings described in Section 4.3.1.2, "Standby State
Sensing Settings". If a sensor input is enabled in both the Active state and in the Standby state, the
Active state settings will be used in Combo state. The programmed cycle time is determined by
STBY_CY_TIME[1:0].
The Combo state also has two gain settings. When the COMBO bit is set, the GAIN[1:0] control only
applies to the se nsors enabled in the Active state, and the C_GAIN[1:0] con trol applies to the sensors
enabled in the Standby state.
4.3.2 Sensing Cycle
Except when in Deep Sleep, the device automatically initiates a sensing cycle and repeats the cycle
every time it finishes. The cycle polls through each enabled sensor input starting with CS1 and
extending through CS6. As each capacitive touch sensor i nput is polled, its measurement is compared
against a baseline “not touched” measurement. If the delta measurement is large enough to exceed
the applicable threshold, a touch is detected and an interrupt can be generated (see Section 4.9.2,
"Capacitive Sensor Input Interrupt Behavior").
The sensing cycle time is programmable (see Section 5.10, "Averaging and Sampling Configuration
Register" and Section 5.23, "Standby Configuration Register"). If all enabled inputs can be sampled in
less than the cycle time, the device is placed into a lower power state for the remainder o f the sensing
cycle. If the number of active sensor inputs cannot be sampled within the specified cycle time, the
cycle time is extended and the device is not placed in a lower power state.
4.4 Sensor Input Calibration
Calibration sets the Base Count Registers (Section 5.26, "Sensor Input Base Count Registers") which
contain the “not touched” values used for touch detection comparisons. Calibration automatically
occurs after a power-on reset (POR), when sample time is changed, when the gain is changed, when
the calibration sensitivity is changed, and whenever a sensor input is newly enabled (for example,
when transitioning from a power state in which i t was disabled to a power state in which it is enabled).
During calibration, the analog sensing circuits are tuned to the capacitance of the untouched pad.
Then, samples are taken from each sensor input so that a base count can be established. After
calibration, the untouched delta counts are zero.
APPLICATION NOTE: During the calibration routine, the sensor inputs will not detect a press for up to 200ms and
the Sensor Base Count Register values will be invalid. In addition, any press on the
corresponding sensor pads will invalidate the calibration.
The host controller can force a calibration for selected sensor inputs at any time using the Calibration
Activate and Status Register (Section 5.11, "Calibration Activate and Status Register"). When a bit is
set, the corresponding capacitive touch sensor input will be calibrated (both analog and digital). The
bit is automatically cleared once the calibration routine has successfully finished.
If analog calibration fails for a sensor input, the corresponding bit is not cleared in the Calibration
Activate and Status Register, and the ACAL_FAIL bit is set in the General Status Register (Section 5.2,
"Status Registers"). An interrupt can be generated. Analog calibration will fail if a noise bit is set or if
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the calibration value is at the maximum or minimum value. If digital calibration fails to generate base
counts for a sensor input in the operating range, which is +12.5% from the ideal base count (see
Table 4.1), indicating the base capacitance is out of range, the corresponding BC_OUTx bit is set in
the Base Count Out of Limit Register (Section 5.18, "Base Count Out of Limit Register"), and the
BC_OUT bit is set in the General Status Register (Section 5.2, "Status Registers"). An interrupt can
be generated. By default, when a base count is out of limit, analog calibration is repeated for the
sensor input; alternatively, the sensor input can be sampled using the out of limit base count (Section
5.6, "Configuration Registers"). Calibration sensitivity can be adjusted for each sensor input based on
capacitive touch pad capacitance.
During normal operation there are various options for recalibrating the capacitive touch sensor inputs.
Recalibration is a digital adjustment of the base counts so that the untouched delta count is zero. After
a recalibration, if a sensor input’s base count has shifted +12.5% from the ideal base count, a full
calibration will be performed on the sensor input.
4.4.1 Automatic Recalibration
Each sensor input is regularly recal ibrated at a p rogrammable rate (see CAL_CFG[2 :0] i n Section 5.19,
"Recalibration Configuration Register"). By default, the recalibration routine stores the average 64
previous measurements and periodically updates the base “not touched” setting for the capacitive
touch sensor input.
APPLICATION NOTE: Automatic recalibration only works when the delta count is below the active sensor input
threshold. It is disabled when a touch is detected.
4.4.2 Negative Delta Count Recalibration
It is possible that the device loses sensitivity to a touch. This may happen as a result of a noisy
environment, recalibration when the pad is touched but delta counts do not exceed the threshold, or
other environmental changes. When this occurs, the base untouched sensor input may generate
negative delta count values. The NEG_DELTA_CNT[1:0] bits (see Section 5.19, "Recalibration
Configuration Register") can be set to force a recalibration after a specified number of consecutive
negative delta readings. After a delayed recalibration (see Section 4.4.3, "Delayed Recalibration") the
negative delta count recalibration can correct after the touch is released.
APPLICATION NOTE: During this recalibration, the device will not respond to touches.
4.4.3 Delayed Recalibration
It is possible that a “stuck button” occurs when some thing is placed on a button wh ich causes a touch
to be detected for a long period. By setting the MAX_DUR_EN bit (see Section 5.6, "Configuration
Registers"), a recalibration can be forced when a touch is held on a button for longer than the dura tion
specified in the MAX_DUR[3:0] bits (see Section 5.8, "Sensor Input Configuration Register").
Table 4.1 Ideal Base Counts
IDEAL BASE COUNT SAMPLE TIME
3,200 320us
6,400 640us
12,800 1.28ms
25,600 2.56ms
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Note 4.1 Delayed recalibration only works when the delta count is above the active sensor input
threshold. If enabled, it is invoked when a sensor pad touch is held longer than the
MAX_DUR bit settings.
Note 4.2 For the power button, which requires that the button be held longer than a regular button,
the time specified by the MAX_DUR[3:0] bits is added to the time required to trigger the
qualifying event. This will prevent the power button from being recalibrated during the time
it is supposed to be held.
4.5 Proximity Detection
Each sensor input can be configured to detect changes in capacitance due to proximity of a touch.
This circuitry detects the change of capacitance that is generated as an object approaches, but does
not physically touch, the enab led sensor pad(s). Generally, sensor i nputs used to detect proximity have
physically larger pads than standard buttons. In addition, gain should be increased to increase
sensitivity. To improve the signal, the signal guard feature may be used.
4.5.1 Signal Guard
The signal guard isolates the signal from virtual grounds, as shown in Figure 4.3. It can be used to
isolate the proximity antenna from nearby conductive surfaces that would otherwise attenuate the e-
field.
4.6 Power Button
The CAP1296 has a “power button” feature. In general, buttons are set for quick response to a touch,
especially when buttons are used for number keypads. However, there are cases where a quick
response is not desired, such as when accidentally brushing the power button cau ses a device to turn
off or on unexpectedly.
The power button feature allows a sensor input to be designated as the “power button” (see Section
5.27, "Power Button Register"). The power button is configured so that a touch must be held on the
button for a designated period of time before an inte rrupt is generated; different times can be selected
for the Standby and the Active states (see Section 5.28, "Power Button Configuration Register"). The
feature can also be enabled / disabled for both states separately.
APPLICATION NOTE: For the power button feature to work in the Standby and/or Active states, the sensor input
must be enabled in the applicable state. If the power button feature is enabled for both
Standby and Active and the COMBO bit is set, the Standby power button settings will be
used.
Figure 4.3 Signal Guard
CAP129X Device
CS pin
SIGNAL_GUARD
CS pin
Touch Pad
Touch Pad
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DS01569A-page 24 2013 Microchip Technology Inc.
After the designated power button has been held for the designated time, an interrupt is generated
and the PWR bit is set in the General Status Register (see Section 5.2, "Status Registers").
4.7 Multiple Touch Pattern Detection
The multiple touch pattern (MTP) detection circuitry can be used to detect lid closure or other similar
events. An event can be flagged based on either a minimum number of sensor inputs or on specific
sensor inputs simultaneously exceeding an MTP threshold or having their Noise Flag Status Register
bits set. An interrupt can also be generated. During an MTP event, all touches are blocked (see
Section 5.16, "Multiple Touch Pattern Configuration Register").
4.8 Noise Controls
4.8.1 Low Frequency Noise Detection
Each sensor input has a low frequency noise detector that will sense if low frequency no ise is injected
onto the input with sufficient power to corrupt the readings. By default, if this occurs, the device will
reject the corrupted sample (see DIS_ANA_NOISE bit in Section 5.6.1, "Configuration - 20h") and the
corresponding bit is set to a logic ‘1’ in the Noise Flag Status register (see SHOW_RF_NOISE bit in
Section 5.6.2, "Configuration 2 - 44h").
4.8.2 RF Noise Detection
Each sensor input contains an integrated RF noise detector. This block will detect injected RF noise
on the CS pin. The detector threshold is dependent upon the noise frequency. By default, if RF noise
is detected on a CS line, that sample is removed and not compared against the threshold (see
DIS_RF_NOISE bit in Section 5.6.2, "Configuration 2 - 44h").
4.8.3 Noise Status and Configuration
The Noise Flag Status (see Section 5.3, "Noise Flag Status Registers") bits can be used to indicate
RF and/or other noise. If the SHOW_RF_NOISE bit in the Configuration Register (see Section 5.6,
"Configuration Registers") is set to 0, the Noise Flag Status bit for the capacitive sensor input is set if
any analog noise is detected. If the SHOW_RF_NOISE bit is set to 1, the Noise Flag Status bits will
only be set if RF noise is detected.
The CAP1296 offers optional noise filtering controls for both analog and digital noise.
For analog noise, there are options for whether the data should be considered invalid. By default, the
DIS_ANA_NOISE bit (see Section 5.6.1, "Configuration - 20h") will block a touch on a sensor input if
low frequency analog noise is detected; the sample is discarded. By default, the DIS_RF_NOISE bit
(see Sectio n 5.6.2, "Configuration 2 - 44h") will bl ock a touch on a sensor input if RF noise is detected;
the sample is discarded.
For digital noise, sensor input noise thresholds can be set (see Section 5.21, "Sensor Input Noise
Threshold Register"). If a capacitive touch sensor input exceeds the Sensor Noise Threshold but does
not exceed the touch threshold (Sensor Threshold (see Section 5.20, "Sensor Input Threshold
Registers") in the Active state or Sensor Standby Threshold in the Standby state (Section 5.25,
"Standby Threshold Register")), it is determined to be caused by a noise spike. The DIS_DIG_NOISE
bit (see Section 5.6.1, "Configuration - 20h") can be set to discard samples that indicate a noise spike
so they are not used in the automatic recalibration routine (see Section 4.4.1, "Automatic
Recalibration").
4.9 Interrupts
Interrupts are indicated by the setting of the INT bit in the Main Control Register (see Section 5.1,
"Main Control Register") and by assertion of the ALERT# pin. The ALERT# pin is cleared when the
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INT bit is cleared by the user. When the INT bit is cleared by the user, status bits may be cleared (see
Section 5.2, "Status Registers").
4.9.1 ALERT# Pin
The ALERT# pin is an active low output that is driven when an interrupt event is detected.
4.9.2 Capacitive Sensor Input Interrupt Behavior
Each sensor input can be programmed to enable / disable interrupts (see Section 5.12, "Interrupt
Enable Register").
When enabled for a sensor input and the sensor input is not the designated power button, interrupts
are generated in one of two ways:
1. An interrupt is generated when a touch is detected and, as a user selectable option, when a release
is detected (by default - see INT_REL_n in Section 5.6.2, "Co nfiguration 2 - 44 h"). See Figure 4.5.
2. If the repeat rate is enabled then, so long as the touch is held, another interrupt will be generated
based on the programmed repeat rate (see Figure 4.4).
When the repeat ra te is enabled for a sensor input (se e Section 5.13, "Repea t Rate Enable Registe r"),
the device uses an additional control called MPRESS that determines whether a touch is flagged as
a simple “touch” or a “press and hold” (see Section 5.9, "Sensor Input Configuration 2 Register"). The
MPRESS[3:0] bits set a minimum press timer. When the button is touched, the timer begins. If the
sensor pad is released before the minimum press timer expires, it is flagged as a touch and an
interrupt (if enabled) is generated upon release. If the sensor input detects a touch for longer than this
timer value, it is flagged as a “press and hold” event. So long as the touch is held, interrupts will be
generated at the programmed repeat rate (see Section 5.8, "Senso r Input Configuration Register") and
upon release (if enabled).
If a sensor input is the designated power button, an interrupt is not generated as soon as a touch is
detected and repeat rate is not applicable. See Section 4.9.3, "Interrupts for the Power Button".
APPLICATION NOTE: Figure 4.4 and Figure 4.5 show default operation which is to generate an interrupt upon
sensor pad release.
APPLICATION NOTE: The host may need to poll the device twice to determine that a release has been detected.
Figure 4.4 Sensor Interrupt Behavior - Repeat Rate Enabled
Touch Detected
INT bit
Button Status
Write to INT bit
Sensing Cycle
(35ms)
Min Press Setting
(280ms)
Interrupt on
Touch
Button Repeat Rate
(175ms) Button Repeat Rate
(175ms)
Interrupt on
Release
(optional)
ALERT# pin
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4.9.3 Interrupts for the Power Button
Interrupts are automatically ena bled for the power button when the featu re is enabled (see Se ction 4 .6,
"Power Button"). A touch must be held on the power button for the designated period of time before
an interrupt is generated.
4.9.4 Interrupts for Multiple Touch Pattern Detection
An interrupt can be generated when the MTP pattern is matched (see Section 5.16, "Multiple Touch
Pattern Configuration Register").
4.9.5 Interrupts for Sensor Input Calibration Failures
An interrupt can be gen erated when the ACAL_FAIL bit is set, indicating the failure to complete anal og
calibration of one or more sensor inputs (see Section 5.2, "Status Registers"). This interrupt can be
enabled by setting the ACAL_FAIL_INT bit (see Section 5.6, "Configuration Registers").
An interrupt can be generated when the BC _OUT bit is set, indicating the base count is out o f limit for
one or more sensor inputs (see Section 5.2, "Status Registers"). This interrupt can be enabled by
setting the BC_OUT_INT bit (see Section 5.6, "Configuration Registers").
Figure 4.5 Sensor Interrupt Behavior - No Repeat Rate Enabled
Touch Detected
INT bit
Button Status
Write to INT bit
Sensing Cycle
(35ms)
Interrupt on
Touch Interrupt on
Release
(optional)
ALERT# pin
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Chapter 5 Register Description
The registers shown in Table 5.1 are accessible through the communications protocol. An entry of ‘-’
indicates that the bit is not used and will always read ‘0’.
Table 5.1 Register Set in Hexadecimal Order
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
00h R/W Main Control Controls power states and indicates
an interrupt 00h Page 30
02h R/W General Status Stores general status bits 00h Page 32
03h R Sensor Input Status Returns the state of the sampled
capacitive touch sensor inputs 00h Page 32
0Ah R Noise Flag Status Stores the noise flags for sensor
inputs 00h Page 33
10h R Sensor Input 1 Delta
Count Stores the delta count for CS1 00h Page 34
11h R Sensor Input 2 Delta
Count Stores the delta count for CS2 00h Page 34
12h R Sensor Input 3 Delta
Count Stores the delta count for CS3 00h Page 34
13h R Sensor Input 4 Delta
Count Stores the delta count for CS4 00h Page 34
14h R Sensor Input 5 Delta
Count Stores the delta count for CS5 00h Page 34
15h R Sensor Input 6 Delta
Count Stores the delta count for CS6 00h Page 34
1Fh R/W Sensitivity Control Controls the sensitivity of the
threshold and delta counts and data
scaling of the base counts 2Fh Page 34
20h R/W Configuration Controls general functionality 20h Page 36
21h R/W Sensor Input Enable Controls which sensor inputs are
monitored in Active 3Fh Page 38
22h R/W Sensor Input
Configuration Controls max duration and auto-
repeat delay A4h Page 38
23h R/W Sensor Input
Configuration 2 Controls the MPRESS (“press and
hold”) setting 07h Page 40
24h R/W Averaging and
Sampling Config Controls averaging and sampling
window for Active 39h Page 41
26h R/W Calibration Activate
and Status Forces calibration for capacitive
touch sensor inputs and indicates
calibration failure 00h Page 42
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27h R/W Interrupt Enable Determines which capacitive sensor
inputs can generate interrupts 3Fh Page 43
28h R/W Repeat Rate Enable Enables repeat rate for specific
sensor inputs 3Fh Page 44
29h R/W Signal Guard Enable Enables the signal guard for specific
sensor inputs 00h Page 45
2Ah R/W Multiple Touch
Configuration Determines the number of
simultaneous touches to flag a
multiple touch condition 80h Page 45
2Bh R/W Multiple Touch Pattern
Configuration Determines the multiple touch
pattern (MTP) configuration 00h Page 46
2Dh R/W Multiple Touch Pattern Determines the pattern or number of
sensor inputs used by the MTP
circuitry 3Fh Page 47
2Eh R Base Count Out of
Limit Indicates whether sensor inputs
have a base count out of limit 00h Page 48
2Fh R/W Recalibration
Configuration Determines recal ibration timing a nd
sampling window 8Ah Page 48
30h R/W Sensor Input 1
Threshold Stores the touch detectio n threshold
for Active for CS1 40h Page 50
31h R/W Sensor Input 2
Threshold Stores the touch detectio n threshold
for Active for CS2 40h Page 50
32h R/W Sensor Input 3
Threshold Stores the touch detectio n threshold
for Active for CS3 40h Page 50
33h R/W Sensor Input 4
Threshold Stores the touch detectio n threshold
for Active for CS4 40h Page 50
34h R/W Sensor Input 5
Threshold Stores the touch detectio n threshold
for Active for CS5 40h Page 50
35h R/W Sensor Input 6
Threshold Stores the touch detectio n threshold
for Active for CS6 40h Page 50
38h R/W Sensor Input Noise
Threshold Stores controls for selecting the
noise threshold for all sensor inputs 01h Page 51
Standby Configuration Registers
40h R/W Standby Channel Controls which sensor inputs are
enabled for Standby 00h Page 51
41h R/W Standby Configuration Controls averaging and sensing
cycle time for Standby 39h Page 52
42h R/W Standby Sensitivity Controls sensitivity setti ngs used fo r
Standby 02h Page 54
43h R/W Standby Threshold Stores the touch detection threshold
for Standby 40h Page 54
Table 5.1 Regi ster Set in Hexadecimal Order (continued)
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
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44h R/W Configuration 2 Stores additional configuration
controls for the device 40h Page 36
Base Count Registers
50h R Sensor Input 1 Base
Count Stores the reference count value for
sensor input 1 C8h Page 55
51h R Sensor Input 2 Base
Count Stores the reference count value for
sensor input 2 C8h Page 55
52h R Sensor Input 3 Base
Count Stores the reference count value for
sensor input 3 C8h Page 55
53h R Sensor Input 4 Base
Count Stores the reference count value for
sensor input 4 C8h Page 55
54h R Sensor Input 5 Base
Count Stores the reference count value for
sensor input 5 C8h Page 55
55h R Sensor Input 6 Base
Count Stores the reference count value for
sensor input 6 C8h Page 55
Power Button Registers
60h R/W Power Button Specifies the power button 00h Page 55
61h R/W Power Button
Configuration Configures the power button feature 22h Page 56
Calibration Sensitivity Configuration Registers
80h R/W Calibration Sensitivity
Configuration 1 Stores calibration sensitivity settings
for proximity 00h Page 58
81h R/W Calibration Sensitivity
Configuration 2 Stores calibration sensitivity settings
for proximity 00h Page 58
Calibration Registers
B1h R Sensor Input 1
Calibration Stores the upper 8-bit calibration
value for CS1 00h Page 57
B2h R Sensor Input 2
Calibration Stores the upper 8-bit calibration
value for CS2 00h Page 57
B3h R Sensor Input 3
Calibration Stores the upper 8-bit calibration
value for CS3 00h Page 57
B4h R Sensor Input 4
Calibration Stores the upper 8-bit calibration
value for CS4 00h Page 57
B5h R Sensor Input 5
Calibration Stores the upper 8-bit calibration
value for CS5 00h Page 57
B6h R Sensor Input 6
Calibration Stores the upper 8-bit calibration
value for CS6 00h Page 57
B9h R Sensor Input
Calibration LSB 1 Store s the 2 LSBs of the calibration
value for CS1 - CS4 00h Page 57
Table 5.1 Regi ster Set in Hexadecimal Order (continued)
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
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During power-on reset (POR), the default values are stored in the registers. A POR is initiated when
power is first applied to the part and the voltage on the VDD supply surpasses the POR level as
specified in the electrical characteristics.
When a bit is “set”, this means it’s at a logic ‘1’. When a bit is “cleared”, this means it’s at a logic ‘0’.
5.1 Main Control Register
The Main Control register controls the primary power state of the device (see Section 4.1, "Power
States").
If more than one power state bit is set, the actual power state will be as shown in Table 5.3, "Power
State Bit Overrides".
Bits 7 - 6 - GAIN[1:0] - Controls the analog gain used by the capacitive touch sensing circuitry. As the
gain is increased, the effective sensitivity is likewise increased as a smaller delta capacitance is
required to generate the same delta count values. The sensitivity settings may need to be adjusted
along with the gain settings such that data overflow does not occur.
APPLICATION NOTE: The GAIN[1:0] settings apply to both Standby and Active states, unless the COMBO bit is
set. When the COMBO bit is set, this control only applies to the sensors enabled in the
BAh R Sensor Input
Calibration LSB 2 Store s the 2 LSBs of the calibration
value for CS5 - CS6 00h Page 57
ID Registers
FDh R Product ID Stores a fixed value that identifies
the CAP1296-1 69h Page 58
FEh R Manufacturer ID Stores a fixed value that identifies
MCHP 5Dh Page 59
FFh R Revision Stores a fixed value that represents
the revision number 00h Page 59
Table 5.2 Main Control Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
00h R/W Main Control GAIN[1:0] STBY DSLEEP C_GAIN[1:0] COMBO INT 00h
Table 5.3 Power St ate Bit Overrides
DSLEEP COMBO STBY POWER STATE
000Active
0 0 1 Standby
0 1 X Combo
1 X X DSleep
Table 5.1 Regi ster Set in Hexadecimal Order (continued)
REGISTER
ADDRESS R/W REGISTER NAME FUNCTION DEFAULT
VALUE PAGE
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Active state, and the C_GAIN[1:0] control applies to the sensors enabled in the Standby
state.
APPLICATION NOTE: Whenever the gain settings change, the device will recalibrate all sensor inputs as if they
had no base count.
Bit 5 - STBY - Enables Standby.
‘0’ (default) - The device is not in the Standby state.
‘1’ - The device is in the Standby state. Capacitive touch sensor input scanning is limited to the
sensor inputs set in the Standby Channel register (see Secti on 5.22, "Standby Channel Register" ).
The status registers will not be cleared until read. Sensor inputs that are no longer sampled will
flag a release and then remain in a non-touched state.
Bit 4 - DSLEEP - Enables Deep Sleep.
‘0’ (default) - The device is not in the Deep Sleep state.
‘1’ - The device is in the Deep Sleep state. All sensor input scanning is disabled. The status
registers are automatically cleared and the INT bit is cleared..
Bits 3 - 2 - C_GAIN[1:0] - When the COMBO bit is set, this bit controls the analog gain used for
capacitive touch sensor inputs enabled in the Standby state. As the gain is increased, the effective
sensitivity is likewise increased as a smaller delta capacitance is required to generate the same delta
count values. The Standby sensitivity settings may need to be adjusted along with the gain settings
such that data overflow does not occur.
APPLICATION NOTE: The C_GAIN[1:0] setting is only used if the COMBO bit is set. When the COMBO bit is set,
this control only applies to the sensors enabled in the Standby state, and the GAIN[1:0]
control applies to the sensors enabled in the Active state.
Bit 1 - COMBO - Enables Combo state (see Section 4.3.1.3, "Combo State Sensing Settings").
‘0’ (default) - The device is not in the Combo state.
‘1’ - The device is in the Combo state. The device is monitori ng sens or inputs enabled in th e Acti ve
state (see Section 5.7, "Sensor Input Enable Register") as well as those enabled in the Standby
state (see Section 5.22, "Standby Channel Registe r"). The status registers will not be cleared unti l
read. Sensor inputs that are no longer sampled will flag a release and then remain in a non-touched
state.
Bit 0 - INT - Indicates that there is an interrupt (see Section 4.9, "Interrupts"). When this bit is set, it
asserts the ALERT# pin. If a channel detects a touch but interrupts are not enabled for that channel
(see Sectio n 5.12, "Interrupt Enable Register"), no action is taken. This bit is cleared by writing a lo gic
‘0’ to it. When this bit is cleared, the ALERT# pin will be deasserted, and all status registers will be
cleared if the condition has been removed.
Table 5.4 GAIN and C_GAIN Bit Decode
GAIN[1:0] OR C_GAIN[1:0]
CAPACITIVE TOUCH SENSOR INPUT GAIN10
00 1
01 2
10 4
11 8
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‘0’ - No interrupt pending.
‘1’ - An interrupt condition occurred, and the ALERT# pin has been asserted.
5.2 Status Registers
All status bits are cleared when the device enters Deep Sleep (DSLEEP = ‘1’ - see Section 5.1, "Main
Control Register").
5.2.1 General Status - 02h
Bit 6 - BC_OUT - Indicates that the base count is out of limit for one or more enabled sensor inputs
(see Section 4.4 , "Sensor Input Calibration"). This bit will not be cle ared until all enabled sensor inputs
have base counts within the limit.
‘0’ - All enabled sensor inputs have base counts in the operating range.
‘1’ - One or more enabled sensor inputs has the base count out of limit. A status bit is set in the
Base Count Out of Limit Register (see Section 5.18, "Base Count Out of Limit Register").
Bit 5 - ACAL_FAIL - Indicates analog calibration failure for one or more enabled sensor inputs (see
Section 4.4, "Sensor Input Calibrati on"). This bit will n ot be cleared unti l all enabled sensor inputs have
successfully completed analog calibration.
‘0’ - All enabled sensor inputs were successfully calibrated.
‘1’ - One or more enabled sensor inputs failed analog calibration. A status bit is set in the
Calibration Active Register (see Section 5.11, "Calibration Activate and Status Register").
Bit 4 - PWR - Indicates that the designated power button has been held for the designated time (see
Section 4.6, "Power Button"). This bi t will cause the INT bit to be set. This bit is cleared when th e INT
bit is cleared if there is no longer a touch on the power button.
‘0’ - The power button has not been held for the required time or is not enabled.
‘1’ - The power button has been held for the required time.
Bit 2 - MULT - Indicates that the device is blocking detected touches due to the Multiple Touch
detection circuitry (see Section 5.15, "Multiple Touch Configuration Register"). This bit will not cause
the INT bit to be set and hence will not cause an interrupt.
Bit 1 - MTP - Indicates that the device has detected a number of sensor inputs that exceed the MTP
threshold either via the pattern recognition or via the number of sensor inputs (see Section 5.16,
"Multiple Touch Pattern Configuration Register"). This bit will cause the INT bit to be set if the
MTP_ALERT bit is also set. This bi t is cleared when the INT bit is cleared if the condition that caused
it to be set has been removed.
Bit 0 - TOU CH - Indicates that a touch was detected. Th is bit is set if any bit in the Sensor Input Status
register is set.
Table 5.5 Status Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
02h R General Status - BC_
OUT ACAL
_FAIL PWR - MULT MTP TOUCH 00h
03h R Sensor Input
Status - - CS6 CS5 CS4 CS3 CS2 CS1 00h
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5.2.2 Sensor Input Status - 03h
The Sensor Input Status Register stores status bits that indicate a touch has been detected. A value
of ‘0’ in any bit indicates that no touch has been detected. A value of ‘1’ in any bit indicates that a
touch has been detected.
All bits are cleared when the INT bit is cl eared and if a tou ch on the respe ctive capaciti ve touch sensor
input is no longer present. If a touch is still detected, th e bits will not be cleared (but this will not ca use
the interrupt to be asserted).
Bit 5 - CS6 - Indicates that a touch was detected on Sensor Input 6.
Bit 4 - CS5 - Indicates that a touch was detected on Sensor Input 5.
Bit 3 - CS4 - Indicates that a touch was detected on Sensor Input 4.
Bit 2 - CS3 - Indicates that a touch was detected on Sensor Input 3.
Bit 1 - CS2 - Indicates that a touch was detected on Sensor Input 2.
Bit 0 - CS1 - Indicates that a touch was detected on Sensor Input 1.
5.3 Noise Flag Status Registers
The Noise Flag Status registers store status bits that can be used to indicate that the analog block
detected noise above the operating regio n o f th e a nalog d etector or the R F noise de te ctor (see Section
4.8.3, "Noise Status and Configuration" ). These bits indicate that the most recently received data from
the sensor input is invalid and should not be used for touch detection. So long as the bit is set for a
particular channel, the delta count value is reset to 00h and thus no touch is detected.
These bits are not sticky and will be cleared automatically if the analog block does not report a noise
error.
APPLICATION NOTE: If the MTP detection circuitry is enabled, these bits count as sensor inputs above the MTP
threshold (see Section 4.7, "Multiple Touch Pattern Detection") even if the corresponding
delta count is not. If the corresponding delta count also exceeds the MT P thre shold, it is not
counted twice.
APPLICATION NOTE: Regardless of the state of the Noise Status bits, if low frequency noise is detected on a
sensor input, that sample will be discarded unless the DIS_ANA_NOISE bit is set. As well,
if RF noise is detected on a sensor input, that sample will be discarded unless the
DIS_RF_NOISE bit is set.
Table 5.6 Noise Flag Status Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
0Ah R Noise Flag
Status --CS6_
NOISE CS5_
NOISE CS4_
NOISE CS3_
NOISE CS2_
NOISE CS1_
NOISE 00h
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5.4 Sensor Input Delta Count Registers
The Sensor Input Delta Count registers store the delta count that is compared against the threshold
used to determine if a touch has been detected. The count value represents a change in input due to
the capacitance associated with a touch on one of the sensor inputs and is referenced to a calibrated
base “not touched” count value. The delta is an in stantaneous change and is updated once per sensor
input per sensing cycle (see Section 4.3.2, "Sensing Cycle").
The value presented is a standard 2’s complement number. In addition, the value is capped at a value
of 7Fh. A reading of 7Fh indicates that the sensitivity settings are too high and should be adjusted
accordingly (see Section 5.5).
The value is also capped at a negative value of 80h for negative delta counts which may result upon
a release.
5.5 Sensitivity Control Register
The Sensitivity Control register controls the sensitivity of a touch detection.
Bits 6-4 DELTA_SENSE[2:0] - Controls the sensitivity of a touch detection for sensor inputs enabled
in the Active state. The sensitivity settings act to scale the relative delta count value higher or lower
based on the system parameters. A sett ing of 000b is the most sensitive while a setting of 111b is the
least sensitive. At the more sensitive settings, touches are detected for a smaller delta capacitance
corresponding to a “lighter” touch. These settings are more sensitive to noise, however, and a noisy
environment may flag more false touches with higher sensitivity levels.
APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitive settings, the
MSB of the Delta Count register re presents 64 out of ~25,000 which co rresponds to a touch
of approximately 0.25% of the base capacitance (or a ΔC of 25fF from a 10pF base
Table 5.7 Sensor Input Delta Count Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
10h R Sensor Input 1
Delta Count Sign 64 32 16 8 4 2 1 00h
11h R Sensor Input 2
Delta Count Sign 64 32 16 8 4 2 1 00h
12h R Sensor Input 3
Delta Count Sign 64 32 16 8 4 2 1 00h
13h R Sensor Input 4
Delta Count Sign 64 32 16 8 4 2 1 00h
14h R Sensor Input 5
Delta Count Sign 64 32 16 8 4 2 1 00h
15h R Sensor Input 6
Delta Count Sign 64 32 16 8 4 2 1 00h
Table 5.8 Sensitivity Contro l Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
1Fh R/W Sensitivity Control - DELTA_SENSE[2:0] BASE_SHIFT[3:0] 2Fh
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capacitance). Conversely, a value of 1x is the least sensitive setting available. At these
settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts
out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance
(or a ΔC of 3.33pF from a 10pF base capacitance).
Bits 3 - 0 - BASE_SHIFT[3:0] - Controls the scaling and data presentation of the Base Count registers.
The higher the value of these bits, the larger the range and the lower the resolution of the data
presented. The scale factor represents the multiplier to the bit-weighting presented in these register
descriptions.
APPLICATION NOTE: The BASE_SHIFT[3:0] bits normally do not need to be updated. These settings will not affect
touch detection o r sensitivity. These bits are sometimes helpful in analyzi ng the Cap Sensi ng
board performance and stability.
Table 5.9 DELTA_SENSE Bit Decode
DELTA_SENSE[2:0]
SENSITIVITY MULTIPLIER210
0 0 0 128x (most sensitive)
001 64x
0 1 0 32x (default)
011 16x
100 8x
101 4x
110 2x
1 1 1 1x - (least sensitive)
Table 5.10 BASE_SHIFT Bit Decode
BASE_SHIFT[3:0] DATA SCALING
FACTOR32 1 0
00 0 0 1x
00 0 1 2x
00 1 0 4x
00 1 1 8x
01 0 0 16x
01 0 1 32x
01 1 0 64x
0 1 1 1 128x
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5.6 Configuration Registers
The Configuration registers control general global functionality that affects the entire device.
5.6.1 Configuration - 20h
Bit 7 - TIMEOUT - Enables the timeout and idle functionality of the SMBus protocol.
‘0’ (default) - The SMBus time out and idle functionality are disabled. The SMBu s interface will not
time out if the clock line is held low. Likewise, it will not reset if both the data and clock lines are
held high for longer than 200us.
‘1’ - The SMBus timeout and idle functionality are enabled. The SMBus interface will reset if the
clock line is held low for longer than 30ms. Likewise, it will reset if both the data and clock lines
are held high for longer than 200us.
Bit 5 - DIS_DIG_NOISE - Determines whether the digital noise threshold (see Section 5.21, "Sensor
Input Noise Threshold Register") is used by the device. Setting this bit disables the feature.
‘0’ - The digital noise thresh old is use d. If a delta cou nt value excee ds the noise thre shold but do es
not exceed the touch threshold, the sample is discarded and not used for the automatic
recalibration routine.
‘1’ (default) - The noise threshol d is disabled. Any delta count that is less than the touch threshold
is used for the automatic recalibration routine.
Bit 4 - DIS_ANA_NOISE - Determines whether the analog noise filter is enabled. Setting this bit
disables the feature.
‘0’ (default) - If low frequency noise is detected by the analog block, the delta count on the
corresponding channel is set to 0. Note that this does not require that Noise Status bits be set.
‘1’ - A touch is not blocked even if low frequency noise is detected.
Bit 3 - MAX_DUR_EN - Determines whether the maximum duration recalibration is enabled.
‘0’ (default) - The maximum duration recalibration functionality is disabled. A touch may be held
indefinitely and no recalibration will be performed on any sensor input.
1 0 0 0 256x
All others 256x
(default = 1111b)
Table 5.11 Configuration Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
20h R/W Configuration TIME
OUT -DIS_
DIG_
NOISE
DIS_
ANA_
NOISE MAX_
DUR_EN - - - 20h
44h R/W Configuration
2-BC_
OUT_
RECAL
BLK_
PWR_
CTRL
BC_
OUT_
INT
SHOW_
RF_
NOISE
DIS_
RF_
NOISE
ACAL
_FAIL
_INT
INT_
REL_
n40h
Table 5.10 BASE_SHIFT Bit Decode (continued)
BASE_SHIFT[3:0] DATA SCALING
FACTOR32 1 0
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‘1’ - The maximum duration recalibration functional ity is enabled. If a touch is held for longer than
the MAX_DUR bit settings (see Section 5.8), the recalibrati on routine will be re started (see Section
4.4.3, "Delayed Recalibration").
5.6.2 Configuration 2 - 44h
Bit 6 - BC_OUT_RECAL - Controls whether to retry analog calibration when the base count is out of
limit for one or more sensor inputs.
‘0’ - When the BC_OUTx bit is set for a sensor input, the out of limit base count will be used for
the sensor input.
‘1’ (default) - When the BC_OUTx bit is set for a sensor input (see Section 5.18, "Base Count Out
of Limit Register"), analog calibration will be repeated on the sensor input.
Bit 5 - BLK_PWR_CTRL - Dete rmines whether the de vice will redu ce power consumption while waiting
between conversion time completion and the end of the sensing cycle.
‘0’ (default) - The device will reduce power consumption during the time between the end of the
last conversion and the end of the sensing cycle.
‘1’ - The device will not reduce power consumption during the time between the end of the last
conversion and the end of the sensing cycle.
Bit 4 - BC_OUT_INT - Controls the interrupt behavior when the base count is out of limit for one or
more sensor inputs.
‘0’ (default) - An interrupt is not generated when the BC_OUT bit is set (see Section 5.2, "Status
Registers").
‘1’ - An interrupt is generated when the BC_OUT bit is set.
Bit 3 - SHOW_RF_NOISE - Determines whether the Noise Status bits will show RF Noise as the only
input source.
‘0’ (default) - The Noise Status registers will show both RF noise and low frequ ency noise if either
is detected on a capacitive touch sensor input.
‘1’ - The Noise S tatus registers will only show RF noise if it is detected on a capacitive touch sensor
input. Low frequency noise will still be detected and touches will be blocke d normally; however, the
status bits will not be updated.
Bit 2 - DIS_RF_NOISE - Determines whether the RF noise filter is enabled. Setting this bit disables
the feature.
‘0’ (default) - If RF noise is detected by the analog block, the delta count on the corresponding
channel is set to 0. Note that this does not require that Noise Status bits be set.
‘1’ - A touch is not blocked even if RF noise is detected.
Bit 1 - ACAL_FAIL_INT - Controls the interrupt behavior when analog calibration fails for one or more
sensor inputs (see Section 4.4, "Sensor Input Calibration").
‘0’ (default) - An interrupt is not generated when the ACAL_FAIL bit is set (see Section 5.2, "Status
Registers").
‘1’ - An interrupt is generated when the ACAL_FAIL bit is set
Bit 0 - INT_REL_n - Controls the interrupt behavior when a release is detected on a button (see
Section 4.9.2, "Capacitive Sensor Input Interrupt Behavior").
‘0’ (default) - An interrupt is generated when a press is detected and again when a release is
detected and at the repeat rate (if enabled - see Section 5.13).
‘1’ - An interrupt is generated when a press is detected and at the repeat rate but not when a
release is detected.
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5.7 Sensor Input Enable Register
The Sensor Input Enable register determines whether a capacitive touch sensor input is included in
the sensing cycle in the Active state.
For all bits in this register:
‘0’ - The specified input is not included in the sensing cycle in the Active state.
‘1’ (default) - The specified input is included in the sensing cycle in the Active state.
Bit 5 - CS6_EN - Determines whether the CS6 input is monitored in the Active state.
Bit 4 - CS5_EN - Determines whether the CS5 input is monitored in the Active state.
Bit 3 - CS4_EN - Determines whether the CS4 input is monitored in the Active state.
Bit 2 - CS3_EN - Determines whether the CS3 input is monitored in the Active state.
Bit 1 - CS2_EN - Determines whether the CS2 input is monitored in the Active state.
Bit 0 - CS1_EN - Determines whether the CS1 input is monitored in the Active state.
5.8 Sensor Input Configuration Register
The Sensor Input Configurat ion Register controls timings associated with the capacitive sensor inputs.
Bits 7 - 4 - MAX_DUR[3:0] - (default 1010b) - Determines the maximum time that a sensor pad is
allowed to be touched until the capacitive touch sensor input is recalibrated (see Section 4.4.3,
"Delayed Recalibration"), as shown in Table 5.14.
Table 5.12 Sensor Input Enable Register
ADDRR/WREGISTERB7 B6B5B4B3B2B1B0DEFAULT
21h R/W Sensor Input
Enable - - CS6_EN CS5_EN CS4_EN CS3_EN CS2_EN CS1_EN 3Fh
Table 5.13 Sensor Input Configuration Register
ADDRR/W REGISTER B7B6 B5B4B3B2B1B0DEFAULT
22h R/W Sensor Input
Configuration MAX_DUR[3:0] RPT_RATE[3:0] A4h
Table 5.14 MAX_DUR Bit Decode
MAX_DUR[3:0]
TIME BEFORE RECALIBRATION32 1 0
0 0 0 0 560ms
0 0 0 1 840ms
0 0 1 0 1120ms
0 0 1 1 1400ms
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Bits 3 - 0 - RPT_RATE[3:0] - (default 0100b) De termin es the time duration betwe en interrupt asserti ons
when auto repeat is enabled (see Section 4.9.2, "Capacitive Sensor Input Interrupt Behavior"). The
resolution is 35ms and the range is from 35ms to 560ms as shown in Table 5.15.
0 1 0 0 1680ms
0 1 0 1 2240ms
0 1 1 0 2800ms
0 1 1 1 3360ms
1 0 0 0 3920ms
1 0 0 1 4480ms
1 0 1 0 5600ms (default)
1 0 1 1 6720ms
1 1 0 0 7840ms
1 1 0 1 8906ms
1 1 1 0 10080ms
1 1 1 1 11200ms
Tabl e 5.15 RPT_RATE Bit Decode
RPT_RATE[3:0]
INTERRUPT REPEAT RATE3210
0000 35ms
0001 70ms
0 0 1 0 105ms
0 0 1 1 140ms
0 1 0 0 175ms (default)
0 1 0 1 210ms
0 1 1 0 245ms
0 1 1 1 280ms
1 0 0 0 315ms
1 0 0 1 350ms
1 0 1 0 385ms
1 0 1 1 420ms
Table 5.14 MAX_DUR Bit Decode (continued)
MAX_DUR[3:0]
TIME BEFORE RECALIBRATION32 1 0
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5.9 Sensor Input Configuration 2 Register
Bits 3 - 0 - M_PRESS[3:0] - (default 0111b) - Determines the minimum amount of time that sensor
inputs configured to use auto repeat must detect a sensor pad touch to detect a “press an d hold” event
(see Section 4.9.2, "Capacitive Sensor Input Interrupt Behavior"). If the sensor input detects a touch
for longer than the M_PRESS[3:0] settings, a “press and hold” event is detected. If a sensor input
detects a touch for less than or equal to the M_PRESS[3:0] settings, a touch event is detected.
The resolution is 35ms and the range is from 35ms to 560ms as shown in Table 5.17.
1 1 0 0 455ms
1 1 0 1 490ms
1 1 1 0 525ms
1 1 1 1 560ms
Tabl e 5.16 Sens or Input Configuration 2 Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
23h R/W Sensor Input
Configuration 2 - - - - M_PRESS[3:0] 07h
Table 5.17 M_PRESS Bit Decode
M_PRESS[3:0]
M_PRESS SETTINGS3210
0000 35ms
0001 70ms
0 0 1 0 105ms
0 0 1 1 140ms
0 1 0 0 175ms
0 1 0 1 210ms
0 1 1 0 245ms
0 1 1 1 280ms (default)
1 0 0 0 315ms
1 0 0 1 350ms
1 0 1 0 385ms
Table 5.15 RPT_RATE Bit Decode (continued)
RPT_RATE[3:0]
INTERRUPT REPEAT RATE3210
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5.10 Averaging and Sampling Configuration Register
The Averaging and Sampling Configuration register controls the number of samples taken and the
target sensing cycle time for sensor inputs enabled in the Active state.
Bits 6 - 4 - AVG[2:0] - Determines the number of samples that are taken for all channels enabled in
the Active state during the sensing cycle as shown in Table 5.19. All samples are taken consecutively
on the same channel before the next channel is sampled and the result is averaged over the number
of samples measured before updating the measured results.
For example, if CS1, CS2, and CS3 are sampled during the sensing cycle, and the AVG[2:0] bits are
set to take 4 samples per channel, then the full sensing cycle will be : CS1, CS1, CS1, CS1, C S2, CS2,
CS2, CS2, CS3, CS3, CS3, CS3.
1 0 1 1 420ms
1 1 0 0 455ms
1 1 0 1 490ms
1 1 1 0 525ms
1 1 1 1 560ms
Table 5.18 Averaging and Sampling Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
24h R/W Averaging and
Sampling
Config - AVG[2:0] SAMP_TIME[1:0] CYCLE_TIME
[1:0] 39h
Table 5.19 AVG Bit Decode
AVG[2:0] NUMBER OF SAMPLES TAKEN
PER MEASUREMENT210
000 1
001 2
010 4
0 1 1 8 (default)
100 16
101 32
110 64
1 1 1 128
Table 5.17 M_PRESS Bit Decode (continued)
M_PRESS[3:0]
M_PRESS SETTINGS3210
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Bits 3 - 2 - SAMP_TIME[1:0] - Determines the time to take a single sample as shown in Table 5.20.
Sample time affects the magnitude of the base counts, as shown in Table 4.1, "Ideal Base Counts".
Bits 1 - 0 - CYCLE_TIME[1 :0] - Determines the desired sensing cycle time for channels enabled in the
Active state, as shown in Table 5.21. All enabled channel s are sampled at the beginnin g of the sensing
cycle. If additional time is remaining, the device is placed into a lower power state for the remainder
of the sensing cycle.
APPLICATION NOTE: The programmed sensing cycle time (CYCLE_TIME[1:0]) is only maintained if the actual time
to take the samples is less than the programmed cycle time. The AVG[2:0] bits will take
priority, so the sensing cycle time will be extended as necessary to accommodate the
number of samples to be measured.
5.11 Calibration Activate and Status Register
The Calibration Activate and Status Register serves a dual function:
1. It forces the selected sensor inputs to be calibrated, affecting both the analog and digital blocks
(see Section 4.4, "Sensor Input Calibration"). When one or more bits are set, the device performs
Table 5.20 SAMP_TIME Bit Decode
SAMP_TIME[1:0]
SAMPLE TIME10
0 0 320us
0 1 640us
1 0 1.28ms (default)
1 1 2.56ms
Table 5.21 CYCLE_TIME Bit Decode
CYCLE_TIME[1:0] PROGRAMMED SENSING CYCLE
TIME10
00 35ms
0 1 70ms (default)
1 0 105ms
1 1 140ms
Table 5.22 Calibration Activate and Status Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
26h R/W Calibration
Activate
and Status --
CS6_
CAL CS5_
CAL CS4_
CAL CS3_
CAL CS2_
CAL CS1_
CAL 00h
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the calibration routine on the corresponding sensor inputs. When the analog calibration routine is
finished, the CALX[9:0] bits are updated (see Section 5.29, "Sensor Input Calibration Registers").
If the analog calibration routine completed successfully for a sensor input, the corresponding bit is
automatically cleared.
APPLICATION NOTE: In the case above, bits can be set by host or are automatically set by the device whenever
a sensor input is newly enabled (such as coming out of Deep Sleep, after power-on reset,
when a bit is set in the Sensor Enable Channel Enable register (21h) and the device is in
the Active state, or when a bit is set in the Standby Channel Enable Register (40h) and the
device is in the Standby state).
2. It serves as an indicator of an analog calibration failure. If any of the bits could not be cleared, the
ACAL_FAIL bit is set (see Section 5.2, "Status Registers"). A bit will fail to clear if a noise bit is set
or if the calibration value is at the maximum or minimum value.
APPLICATION NOTE: In the case above, do not check the Calibration Activate and Status bits for failures unless
the ACAL_FAIL bit is set. In addition, if a sensor input is newly enabled, do not check the
Calibration Activate and Status bits until time has elapsed to complete calibration on the
sensor input. Otherwise, the ACAL_FAIL bit may be set for one sensor input, but the newly
enabled sensor input may still be set to ‘1’ in the Calibration Activate and Status, not because
it failed, but because it has not been calibrated yet.
For all bits in this register:
‘0’ - No action needed.
‘1’ - Writing a ‘1’, forces a calibration on the corresponding sensor input. If the ACAL_FAIL flag is
set and this bit is set (see application note above), the sensor input could not complete analog
calibration.
Bit 5 - CS6_CAL - Bit for CS6 input.
Bit 4 - CS5_CAL - Bit for CS5 input.
Bit 3 - CS4_CAL - Bit for CS4 input.
Bit 2 - CS3_CAL - Bit for CS3 input.
Bit 1 - CS2_CAL - Bit for CS2 input.
Bit 0 - CS1_CAL - Bit for CS1 input.
APPLICATION NOTE: Writing a ‘0’ to clear a ‘1’ may cause a planned calibration to be skipped, if the calibration
routine had not reached the sensor input yet.
5.12 Interrupt Enable Register
The Interrupt Enable register determines whether a sensor pad touch or release (if enabled) causes
an interrupt (see Section 4.9, "Interrupts").
Table 5.23 Interrupt Enable Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
27h R/W Interrupt
Enable --
CS6_
INT_EN CS5_
INT_EN CS4_
INT_EN CS3_
INT_EN CS2_
INT_EN CS1_
INT_EN 3Fh
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For all bits in this register:
‘0’ - The ALERT# pin will not be asserted if a touch is detected on the specified sensor input.
‘1’ (default) - The ALERT# pin will be asserted if a touch is detected on the specified sensor inp ut.
Bit 5 - CS6_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS6
(associated with the CS6 status bit).
Bit 4 - CS5_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS5
(associated with the CS5 status bit).
Bit 3 - CS4_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS4
(associated with the CS4 status bit).
Bit 2 - CS3_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS3
(associated with the CS3 status bit).
Bit 1 - CS2_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS2
(associated with the CS2 status bit).
Bit 0 - CS1_INT_EN - Enables the ALERT# pin to be asserted if a touch is detected on CS1
(associated with the CS1 status bit).
5.13 Repeat Rate Enable Register
The Repeat Rate Enable registe r e nables the repeat rate of the sensor inputs as described in Section
4.9.2, "Capacitive Sensor Input Interrupt Behavior".
For all bits in this register:
‘0’ - The repeat rate for the specified sensor input is disabled. It will only generate an interrupt when
a touch is detected and when a release is detected (if enabled) no matter how long the touch is
held.
‘1’ (default) - The repeat rate for the specified sensor input is enabled. In the case of a “touch”
event, it will generate an interrupt when a touch is detected and a release is detected (as
determined by the INT_REL_n bit - see Section 5.6, "Configuration Registers"). In the case of a
“press and hol d” event, it will gene rate a n interrupt when a tou ch is detected and at the repeat rate
so long as the touch is held.
Bit 5 - CS6_RPT_EN - Enables the repeat rate for capacitive touch sensor input 6.
Bit 4 - CS5_RPT_EN - Enables the repeat rate for capacitive touch sensor input 5.
Bit 3 - CS4_RPT_EN - Enables the repeat rate for capacitive touch sensor input 4.
Bit 2 - CS3_RPT_EN - Enables the repeat rate for capacitive touch sensor input 3.
Bit 1 - CS2_RPT_EN - Enables the repeat rate for capacitive touch sensor input 2.
Bit 0 - CS1_RPT_EN - Enables the repeat rate for capacitive touch sensor input 1.
Table 5.24 Repeat Rate Enable Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
28h R/W Repeat Rate
Enable --
CS6_
RPT_EN CS5_
RPT_EN CS4_
RPT_EN CS3_
RPT_EN CS2_
RPT_EN CS1_
RPT_EN 3Fh
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5.14 Signal Guard Enable Register
The Signal Guard Ena ble register enabl es the si gnal guard for the sp ecified senso r inpu ts as described
in Section 4.5.1, "Signal Guard". When the signal guard is enabled, CS3 is disabled.
For all bits in this register:
‘0’ (default) - The signal guard is disabled for the specified sensor input.
‘1’ - The signal guard is enabled for the specified sensor input.
Bit 5 - CS6_SG_EN - Enables the signal guard for capacitive touch sensor input 6.
Bit 4 - CS5_SG_EN - Enables the signal guard for capacitive touch sensor input 5.
Bit 3 - CS4_SG_EN - Enables the signal guard for capacitive touch sensor input 4.
Bit 1 - CS2_SG_EN - Enables the signal guard for capacitive touch sensor input 2.
Bit 0 - CS1_SG_EN - Enables the signal guard for capacitive touch sensor input 1.
5.15 Multiple Touch Configuration Register
The Multiple Touch Configuration register co ntrols the settings for the multiple t ouch detection circuitry.
These settings determine the number of simultaneous buttons that may be pressed before additional
buttons are blocked and the MULT status bit is set.
Bit 7 - MULT_BLK_EN - Enables the multiple button blocking circuitry.
‘0’ - The multiple touch circuitry is disabled. The device will not block multiple touches.
‘1’ (default) - The multiple touch circuitry is enabled. The device will flag the number of touches
equal to programme d multiple touch threshold and block all others. It will remembe r which sensor
inputs are valid and block all others until that sensor pad has been released. Once a sensor pad
has been released, the N detected touches (determi ned via the sensing cycle order o f CS1 - CS6)
will be flagged and all others blocked.
Bits 3 - 2 - B_MULT_T[1:0] - Determines the number of simultaneous touches on all sensor pads
before a Multiple Touch Event is detected and sensor inputs are blocked. The bit decode is given by
Table 5.27.
Table 5.25 Signal Guard Enable Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
29h R/W Signal
Guard
Enable --
CS6_
SG_EN CS5_
SG_EN CS4_
SG_EN -CS2_
SG_EN CS1_
SG_EN 00h
Table 5.26 Multiple Touch Configuration
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
2Ah R/W Multiple T ouch
Config MULT_
BLK_
EN - - - B_MULT_T[1:0] - - 80h
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5.16 Multiple Touch Pattern Configuration Register
The Multiple Touch Pattern Configuration register controls the settings for the multiple touch pattern
detection circuitry. This circuitry works like the multiple touch detection circuitry with the following
differences:
1. The detection threshold is a percentage of the touch detection threshold as defined by the
MTP_TH[1:0] bits whereas the multiple touch circuitry uses the touch detection threshold.
2. The MTP detection circuitry either will detect a specific pattern of sensor inputs as determined by
the Multiple Touch Pattern register settings or it will use the Multiple Touch Pattern register settings
to determine a minimum nu mber of sensor inputs that will cause the MTP circuitry to flag an event
(see Section 5.17, "Multiple Touch Pattern Register"). When using pattern recognition mode, if all
of the sensor inputs set by the Multiple Touch Pattern register have a delta count greater than the
MTP threshold or have their corresponding Noise Fl ag Status bits set, the MTP bit will be set. When
using the absolute number mode, if the number of sensor inputs with thresholds above the MTP
threshold or with Noise Flag Status bits set is equal to or greater than this number, the MTP bit
will be set.
3. When an MTP event occurs, all touches are blocked and an interrupt is generated.
4. All sensor inputs will remain blocked so long as the requisite number of sensor inputs are above
the MTP threshold or have Noise Flag Status bits set. Once this condition is removed, touch
detection will be restored. Note that the MTP status bit is only cleared by writing a ‘0’ to the INT
bit once the condition has been removed.
Bit 7 - MTP_EN - Enables the multiple touch pattern detection circuitry.
‘0’ (default) - The MTP detection circuitry is disabled.
‘1’ - The MTP detection circuitry is enabled.
Bits 3 - 2 - MTP_TH[1:0] - Determine the MTP threshold, as shown in Table 5.29. This threshold is a
percentage of sensor input threshold (see Sectio n 5.20, "Sensor Input Threshold Registers") for inputs
enabled in the Active state or of the standby threshold (see Section 5.25, "Standby Threshold
Register") for inputs enabled in the Standby state.
Table 5.27 B_MULT_T Bit Decode
B_MULT_T[1:0]
NUMBER OF SIMULTANEOUS TOUCHES10
0 0 1 (default)
01 2
10 3
11 4
Table 5.28 Multiple Touch Pattern Configuration
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
2Bh R/W Multiple T ouch
Pattern Config MTP_ EN - - - MTP_TH[1:0] COMP_
PTRN MTP_
ALERT 00h
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Bit 1 - COMP_PTRN - Determines whether the MTP detection circuitry will use the Multiple Touch
Pattern register as a specific pattern of sensor inputs or as an absolute number of sensor inputs.
‘0’ (default) - The MTP detection circuitry will use the Multiple Touch Pattern register bit se ttings as
an absolute minimum number of sensor inputs that must be above the threshold or have Noise
Flag Status bits set. The number will be equal to the number of bits set in the register.
‘1’ - The MTP detection circuitry will use pattern recognition. Each bit set in the Multiple Touch
Pattern register indicates a specific sensor input tha t must have a delta count greater than the MTP
threshold or have a Noise Flag Status bit set. If the criteria are met, the MTP status bit will be set.
Bit 0 - MTP_ALERT - Enables an interrupt if an MTP event occurs. In either condition, the MTP status
bit will be set.
‘0’ (default) - If an MTP event occurs, the ALERT# pin is not asserted.
‘1’ - If an MTP event occurs, the ALERT# pin will be asserted.
5.17 Multiple Touch Pattern Register
The Multiple Touch Pattern register acts as a pattern to identify an expected sensor input profile for
diagnostics or other significant events. There are two methods for how the Multiple Touch Pattern
register is used: as specific sensor inputs or number of sensor input that must exceed the MTP
threshold or have Noise Flag Status bits set. Which method is used is based on the COMP_PTRN bit
(see Section 5.16). The methods are described below.
1. Specific Sensor Inputs: If, during a single sensing cycle, the specific sensor inputs above the MTP
threshold or with Noise Flag Status bits set match those bits set in the Multiple Touch Pattern
register, an MTP event is flagged.
2. Number of Sensor Inputs: If, during a single sensing cycle , the number of sensor inputs with a delta
count above the MTP threshold or with Noise Flag Status bits set is equal to or greater than the
number of pattern bits set, an MTP event is flagged.
Table 5.29 MTP_TH Bit Decode
MTP_TH[1:0]
THRESHOLD DIVIDE SETTING10
0 0 12.5% (default)
0125%
1 0 37.5%
1 1 100%
Table 5.30 Multiple Touch Pattern Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
2Dh R/W Multiple
Touch
Pattern --
CS6_
PTRN CS5_
PTRN CS4_
PTRN CS3_
PTRN CS2_
PTRN CS1_
PTRN 3Fh
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For all bits in this register:
‘0’ - The specified sensor input is not considered a part of the pattern.
‘1’ - The specified sensor input is considered a part of the pattern, or the absolute number of sensor
inputs that must have a delta count greater than the MTP threshold or have the Noise Flag Status
bit set is increased by 1.
Bit 5 - CS6_PTRN - Determines whether CS6 is considered as part of the Multiple Touch Pattern.
Bit 4 - CS5_PTRN - Determines whether CS5 is considered as part of the Multiple Touch Pattern.
Bit 3 - CS4_PTRN - Determines whether CS4 is considered as part of the Multiple Touch Pattern.
Bit 2 - CS3_PTRN - Determines whether CS3 is considered as part of the Multiple Touch Pattern.
Bit 1 - CS2_PTRN - Determines whether CS2 is considered as part of the Multiple Touch Pattern.
Bit 0 - CS1_PTRN - Determines whether CS1 is considered as part of the Multiple Touch Pattern.
5.18 Base Count Out of Limit Register
The Base Count Out of Limit Register indicates whic h sensor inputs have base counts out of limit (see
Section 4.4, "Sensor Input Calibration"). When these bits are set, the BC_OUT bit is set (see Section
5.2, "Status Registers").
For all bits in this register:
‘0’ - The base count for the specified sensor input is in the operating range.
‘1’ - The base count of the specified sensor input is not in the operating range.
Bit 5 - BC_OUT_6 - Indicates whether CS6 has a base count out of limit.
Bit 4 - BC_OUT_5 - Indicates whether CS6 has a base count out of limit.
Bit 3 - BC_OUT_4 - Indicates whether CS6 has a base count out of limit.
Bit 2 - BC_OUT_3 - Indicates whether CS3 has a base count out of limit.
Bit 1 - BC_OUT_2 - Indicates whether CS2 has a base count out of limit.
Bit 0 - BC_OUT_1 - Indicates whether CS1 has a base count out of limit.
5.19 Recalibration Configuration Register
Table 5.31 Base Count Out of Limit Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0
DEFAULT
2Eh R Base Count
Out of Limit --
BC_
OUT_
6
BC_
OUT_
5
BC_
OUT_
4
BC_
OUT_
3
BC_
OUT_
2
BC_
OUT_
100h
Table 5.32 Recalibration Configuration Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
2Fh R/W Recalibration
Configuration BUT_
LD_TH NO_CLR
_INTD NO_CLR
_NEG NEG_DELTA_
CNT[1:0] CAL_CFG[2:0] 8Ah
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The Recalibration Configuration register controls some recalibration routine settings (see Section 4.4,
"Sensor Input Calibration") as well as advanced controls to program the Sensor Input Threshold
register settings.
Bit 7 - BUT_LD_TH - Enables setting all Sensor Input Threshold registers by writing to the Sensor
Input 1 Threshold register.
‘0’ - Each Sensor Input X Threshold register is updated individually.
‘1’ (default) - Writing the Sensor Input 1 Threshol d register will automatically overwrite the Se nsor
Input Threshold registers for all sensor inputs (Sensor Input Threshold 1 through Sensor Input
Threshold 6). The indi vidua l Sensor Input X Threshold registers (Sensor Input 2 T hreshold through
Sensor Input 6 Threshold) can be individually updated at any time.
Bit 6 - NO_CLR_INTD - Controls whether the accumulati on of intermediate data is cleared if the noise
status bit is set.
‘0’ (default) - The accumulation of intermediate data is cleared if the noise status bit is set.
‘1’ - The accumulation of intermediate data is not cleared if the noise status bit is set.
APPLICATION NOTE: Bits 5 and 6 should both be set to the same value. Either both should be set to ‘0’ or both
should be set to ‘1’.
Bit 5 - NO_CLR_NEG - Controls whether the consecutive negative delta counts counter is cleared if
the noise status bit is set.
‘0’ (default) - The consecutive negative delta counts counter is cleared if the noise status bit is set.
‘1’ - The consecutive negative delta counts counter is not cleared if the noise status bit is set.
Bits 4 - 3 - NEG_DELTA_CNT[1:0] - Determines the number of negative delta counts necessary to
trigger a digital recalibration (see Section 4.4.2, "Negative Delta Count Recalibration"), as shown in
Table 5.33.
Bits 2 - 0 - CAL_CFG[2:0] - Determines the update time and number of samples of the automatic
recalibration routine (see Section 4.4.1, "Automatic Recalibration"). The settings apply to all sensor
inputs universally (though individual sensor inputs can be configured to support recalibration - see
Section 5.11).
Table 5.33 NEG_DELTA_CNT Bit Decode
NEG_DELTA_CNT[1:0] NUMBER OF CONSECUTIVE NEGATIVE DELTA
COUNT VALUES10
00 8
0 1 16 (default)
10 32
1 1 None (disabled)
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Note 5.1 Recalibration Samples refers to the number of samples that are measured and averaged
before the Base Count is u pdate d ho wever does not con trol the base count upda te period.
Note 5.2 Update Time refers to the amount of time (in sensing cycle periods) that elapses before
the Base Count is updated. The time will depend upon the number of channels enabled,
the averaging setting, and the programmed sensing cycle time.
5.20 Sensor Input Threshold Registers
The Sensor Input Threshold registers store the delta threshold that is used to determine if a touch has
been detected. When a touch occurs, the input signal of the corresponding sensor pad changes due
to the capacitance associated with a touch. If the sensor input change excee ds the threshold settings,
a touch is detected.
Table 5.34 CAL_CFG Bit Decode
CAL_CFG[2:0] RECALIBRATION
SAMPLES (SEE
Note 5.1) UPDATE TIME (SEE
Note 5.2)210
0 0 0 16 16
001 32 32
0 1 0 64 64 (default)
0 1 1 128 128
100 256 256
1 0 1 256 1024
1 1 0 256 2048
1 1 1 256 4096
Table 5.35 Sensor Input Threshold Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
30h R/W Sensor Inp ut 1
Threshold -6432168421 40h
31h R/W Sensor Inp ut 2
Threshold -6432168421 40h
32h R/W Sensor Inp ut 3
Threshold -6432168421 40h
33h R/W Sensor Inp ut 4
Threshold -6432168421 40h
34h R/W Sensor Inp ut 5
Threshold -6432168421 40h
35h R/W Sensor Inp ut 6
Threshold -6432168421 40h
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When the BUT_LD_TH bit is set (see Section 5.19 - bit 7), w riting data to the Sensor Inpu t 1 Thresho ld
register will update all of the Sensor Input Threshold registers (31h - 35h inclusive).
5.21 Sensor Input Noise Threshold Register
The Sensor Input Noise Threshold register controls the value of a secondary internal threshold to
detect noise and improve the auto matic recalibration routine . If a capacitive touch sensor inpu t exceeds
the Sensor Input Noise Threshold but does not exceed the sensor input threshold, it is determined to
be caused by a noise spike. That sample is not used by the automatic recalibration routine. This
feature can be disabled by setting the DIS_DIG_NOISE bit.
Bits 1-0 - CS1_BN_TH[1:0] - Controls the noise threshold for all capacitive touch sensor inputs, as
shown in Table 5.37. The threshold is proportional to the threshold setting.
5.22 Standby Channel Register
The Standby Channel register controls which (if any) capacitive touch sensor inputs are enabled in
Standby (see Section 4.3.1.2, "Standby State Sensing Settings").
For all bits in this register:
‘0’ (default) - The specified channel will not be monitored in Standby.
‘1’ - The specified channel will be monitored in Standby. It will use the standby threshold setting,
and the standby averaging and sensitivity settings.
Table 5.36 Senso r Input Noise Threshold Reg ister
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
38h R/W Sensor Input
Noise Threshold ------
CS_BN_TH
[1:0] 01h
Table 5.37 CSx_BN_TH Bit Decode
CS_BN_TH[1:0]
PERCENT THRESHOLD SETTING10
0025%
0 1 37.5% (default)
1050%
1 1 62.5%
Table 5.38 Standby Channel Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
40h R/W Standby
Channel --
CS6_
STBY CS5_
STBY CS4_
STBY CS3_
STBY CS2_
STBY CS1_
STBY 00h
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Bit 5 - CS6_STBY - Controls whether the CS6 channel is enabled in Standby.
Bit 4 - CS5_STBY - Controls whether the CS5 channel is enabled in Standby.
Bit 3 - CS4_STBY - Controls whether the CS4 channel is enabled in Standby.
Bit 2 - CS3_STBY - Controls whether the CS3 channel is enabled in Standby.
Bit 1 - CS2_STBY - Controls whether the CS2 channel is enabled in Standby.
Bit 0 - CS1_STBY - Controls whether the CS1 channel is enabled in Standby.
5.23 Standby Configuration Register
The Standby Configuration register controls averaging and sensing cycle time for sensor inputs
enabled in Standby. This register allows the user to change averaging and sample times on a limited
number of sensor inputs in Standby and still maintain normal functionality in the Active state.
Bit 7 - AVG_SUM - Determines whether the sensor inputs enabled in Standby will average the
programmed number of samples or whether they will accumulate for the programmed number of
samples.
‘0’ - (default) - The Standby enabled sensor inpu t delta count values will be based on the average
of the programmed number of samples when compared against the threshold.
‘1’ - The Standby enabled sensor input delta count values will be based on the summation of the
programmed number of samples when compared against the threshold. Caution should be used
with this setting as a touch may overflow the delta count registers and may result in false readings.
Bits 6 - 4 - STBY_AVG[2:0] - Determines th e number of samples that are taken for all Standby enabled
channels during the sensing cycle as shown in Table 5.40. All sampl es are taken consecutively on the
same channel before the next channel is sampled and the result is averaged over the number of
samples measured before updating the measured results.
Table 5.39 Standby Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
41h R/W Standby
Configuration AVG_
SUM STBY_AVG[2:0] STBY_SAMP_
TIME[1:0] STBY_CY_TIME
[1:0] 39h
Table 5.40 STBY_AVG Bit Decode
STBY_AVG[2:0] NUMBER OF SAMPLES TAKEN
PER MEASUREMENT210
000 1
001 2
010 4
0 1 1 8 (default)
100 16
101 32
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Bit 3 - 2 - STBY_SAMP_TIME[1:0] - Determines the time to take a single sample for sensor inputs
enabled in Standby as shown in Table 5.41.
Bits 1 - 0 - STBY_CY_TIME[2:0] - Determines the desired sensing cycle time for sensor inputs enabled
during Standby, as shown in Table 5.42. This control is also used to determine p rogrammed cycle time
in the Combo state (see Section 4.3.1.3, "Combo State Sensing Settings"). All enabled channels are
sampled at the beginning of the sensing cycle. If additional time is remaining, the device is placed into
a lower power state for the remainder of the sensing cycle.
APPLICATION NOTE: The programmed sensing cycle time (STDBY_CY_TIME[1:0] is only maintained if the actual
time to take the samples is less than the programmed cycle time. The STBY_AVG[2:0] bits
will take priority, so the sensing cycle time will be extended as necessary to accommodate
the number of samples to be measured.
110 64
1 1 1 128
Table 5.41 STBY_SAMP_TIME Bit Decode
STBY_SAMP_TIME[1:0]
SAMPLING TIME10
0 0 320us
0 1 640us
1 0 1.28ms (default)
1 1 2.56ms
Table 5.42 STBY_CY_TIME Bit Decode
STBY_CY_TIME[1:0] PROGRAMMED SENSING CYCLE
TIME10
00 35ms
0 1 70ms (default)
1 0 105ms
1 1 140ms
Table 5.40 STBY_AVG Bit Decode (continued)
STBY_AVG[2:0] NUMBER OF SAMPLES TAKEN
PER MEASUREMENT210
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5.24 Standby Sensitivity Register
The Standby Sensitivity register controls the sensitivity for sensor inputs enabled in Standby.
Bits 2 - 0 - STBY_SENSE[2:0] - Controls the sensitivity for sensor inputs that are enabled in Standby.
The sensitivity settings act to scale the relative delta count value higher or lower based on the system
parameters. A setting of 000b is the most sensitive while a setting of 111b is the least sensiti ve. At the
more sensitive settings, touches are detected for a smaller delta capacitance corresponding to a
“lighter” touch. These settings are more sensitiv e to noise, however, and a noisy environment may flag
more false touches than higher sensitivity levels.
APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitivity settings, the
MSB of the Delta Count register re presents 64 out of ~25,000 which co rresponds to a touch
of approximately 0.25% of the base capacitance (or a ΔC of 25fF from a 10pF base
capacitance). Conversely a value of 1x is the least sensitive setting available. At these
settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts
out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance
(or a ΔC of 3.33pF from a 10pF base capacitance).
5.25 Standby Threshold Register
Table 5.43 Standby Sensitivity Register
ADDRR/WREGISTER B7 B6B5B4B3B2B1B0DEFAULT
42h R/W Standby
Sensitivity - - - - - STBY_SENSE[2:0] 02h
Table 5.44 STBY_SENSE Bit Decode
STBY_SENSE[2:0]
SENSITIVITY MULTIPLIER210
0 0 0 128x (most sensitive)
001 64x
0 1 0 32x (default)
011 16x
100 8x
101 4x
110 2x
1 1 1 1x - (least sensitive)
Table 5.45 Standby Threshold Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
43h R/W Standby
Threshold -6432168421 40h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 55
The Standby Threshold register stor es the delta thres hold that is used to determine if a touch has been
detected. When a touch occurs, the input signal of the corresponding sensor pad changes due to the
capacitance associated with a touch. If the sensor input change exceeds the threshold settings, a
touch is detected.
5.26 Sensor Input Base Count Registers
The Sensor Input Base Count registers store the calibrated “not touched” input value from the
capacitive touch sensor inputs. These registers are periodically updated by the calibration and
recalibration routines.
The routine uses an internal adder to add the current count value for each reading to the sum of the
previous readings until sample size has been reached. At this point, the upper 16 bits are taken and
used as the Sensor Input Base Count. The internal adder is then reset and the recalibration routine
continues.
The data presented is determined by the BASE_SHIFT[3:0] bits (see Section 5.5).
5.27 Power Button Register
The Power Button Register indicates the sensor input that has been designated as the power button
(see Section 4.6, "Power Button").
Bits 2 - 0 - PWR_BTN[2:0] - When the power button feature is enabled, this control indicates the
sensor input to be used as the power button. The decode is shown in Table 5.48.
Tabl e 5.46 Sensor Input Base Count Registe rs
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
50h R Sensor Input 1
Base Count 128 64 32 16 8 4 2 1 C8h
51h R Sensor Input 2
Base Count 128 64 32 16 8 4 2 1 C8h
52h R Sensor Input 3
Base Count 128 64 32 16 8 4 2 1 C8h
53h R Sensor Input 4
Base Count 128 64 32 16 8 4 2 1 C8h
54h R Sensor Input 5
Base Count 128 64 32 16 8 4 2 1 C8h
55h R Sensor Input 6
Base Count 128 64 32 16 8 4 2 1 C8h
Table 5.47 Power Button Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
60h R/W Power Button - - - - - PWR_BTN[2:0] 00h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 56 2013 Microchip Technology Inc.
5.28 Power Button Configuration Register
The Power Button Configuration Register controls the length of time that the designated power button
must indicate a touch before an interrupt is generated and the power status indicator is set (see
Section 4.6, "Power Button").
Bit 6 - STBY_PWR_EN - Enables the power button feature in the Standby state.
‘0’ (default) - The Standby power button circuitry is disabled.
‘1’ - The Standby power button circuitry is enabled.
Bits 5 - 4 - STBY_PWR_TIME[1:0] - Determines the overall time, as shown in Table 5.50, that the
power button must be held i n the Standby state, in order for an interrupt to be generated and the PWR
bit to be set.
Bit 2 - PWR_EN - Enables the power button feature in the Active state.
‘0’ (default) - The power button circuitry is disabled in the Active state.
‘1’ -The power button circuitry is enabled in the Active state.
Bits 1 - 0 - PWR_TIME[1:0] - Determines the overall time, as shown in Table 5.50, that the power
button must be held in the Active state, in order for an interrupt to be generated and the PWR bit to
be set.
Table 5.48 PWR_BTN Bit Decode
PWR_BTN[3:0]
SENSOR INPUT DESIGNATED AS POWER BUTTON201
000 CS1
001 CS2
010 CS3
011 CS4
100 CS5
101 CS6
Table 5.49 Power Button Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
61h R/W Power Button
Configuration -STBY_
PWR_
EN STBY_PWR_
TIME [1:0] -PWR_
EN PWR_TIME [1:0] 22h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 57
5.29 Sensor Input Calibration Registers
The Sensor Input Calibration registers hold the 10-bit value that represents the last calibration value.
The value represents the capacitance applied to the internal sensing circuits to balance the
capacitance of the sensor input pad. Minimum (000h) and maximum (3FFh) values indicate analog
calibration failure (see Section 4.4, "Sensor Input Calibration").
Table 5.50 Power Button Time Bits Decode
PWR_TIME[1:0] / STBY_PWR_TIME[1:0]
POWER BUTTON TOUCH HOLD TIME10
0 0 280ms
0 1 560ms
1 0 1.12 sec (default)
1 1 2.24 sec
Table 5.51 Sensor Input Calibration Registers
ADDR REGISTER R/W B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
B1h Sensor Input 1
Calibration R CAL1_9 CAL1_8 CAL1_7 CAL1_6 CAL1_5 CAL1_4 CAL1_3 CAL1_2 00h
B2h Sensor Input 2
Calibration R CAL2_9 CAL2_8 CAL2_7 CAL2_6 CAL2_5 CAL2_4 CAL2_3 CAL2_2 00h
B3h Sensor Input 3
Calibration R CAL3_9 CAL3_8 CAL3_7 CAL3_6 CAL3_5 CAL3_4 CAL3_3 CAL3_2 00h
B4h Sensor Input 4
Calibration R CAL4_9 CAL4_8 CAL4_7 CAL4_6 CAL4_5 CAL4_4 CAL4_3 CAL4_2 00h
B5h Sensor Input 5
Calibration R CAL5_9 CAL5_8 CAL5_7 CAL5_6 CAL5_5 CAL5_4 CAL5_3 CAL5_2 00h
B6h Sensor Input 6
Calibration R CAL6_9 CAL6_8 CAL6_7 CAL6_6 CAL6_5 CAL6_4 CAL6_3 CAL6_2 00h
B9h Sensor Input
Calibration
LSB 1 R CAL4_1 CAL4_0 CAL3_1 CAL3_0 CAL2_1 CAL2_0 CAL1_1 CAL1_0 00h
BAh Sensor Input
Calibration
LSB 2 R - - - - CAL6_1 CAL6_0 CAL5_1 CAL5_0 00h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 58 2013 Microchip Technology Inc.
5.30 Calibration Sensitivity Configuration Registers
CALSENx[1:0] - Controls the gain used by the calibration routine to enable sensor inputs to be more
sensitive for proximity detection. Gain is based on capacitance touch pad capacitance ranges, as
shown in Table 5.53. Since each sensor input can h ave a different pad capacitan ce, each sensor input
has a control.
5.31 Product ID Register
The Product ID register stores a unique 8-bit value that identifies the device.
5.32 Manufacturer ID Register
The Vendor ID register stores an 8-bit value that represents MCHP.
Table 5.52 Calibration Sensitivity Configur ation Registers
ADDR REGISTER R/W B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
80h Calibration
Sensitivity
Config 1 R/W CALSEN4[1:0] CALSEN3[1:0] CALSEN2[1:0] CALSEN1[1:0] 00h
81h Calibration
Sensitivity
Config 2 R/W----CALSEN6[1:0]CALSEN5[1:0]00h
Table 5.53 CALSENX Bit Decode
CALSENX[1:0]
GAIN CAPACITIVE TOUCH PAD
CAPACITANCE RANGE10
0 0 1 5-50pF (default)
012 0-25pF
1 0 4 0-12.5pF
Table 5.54 Product ID Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FDh R Product ID
CAP1296-1 01101001 69h
Table 5.55 Vendor ID Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FEh RManufacturer ID01011101 5Dh
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 59
5.33 Revision Register
The Revision register stores an 8-bit value that represents the part revision.
Table 5.56 Revision Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FFhR Revision 00000000 00h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 60 2013 Microchip Technology Inc.
Chapter 6 Package Information
6.1 CAP1296 Package Drawings
Figure 6.1 CAP1296 Package Drawing - 10-Pin DFN 3mm x 3mm
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 61
Figure 6.2 CAP1296 Package Dimensions - 10-Pin DFN 3mm x 3mm
Figure 6.3 CAP1296 PCB Land Pattern and Stencil - 10-Pin DFN 3mm x 3mm
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 62 2013 Microchip Technology Inc.
Figure 6.4 CAP1296 PCB Detail A - 10-Pin DFN 3mm x 3mm
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 63
Figure 6.5 CAP1296 PCB Detail B - 10-Pin DFN 3mm x 3mm
Figure 6.6 CAP1296 Land Dimensions - 10-Pin DFN 3mm x 3mm
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 64 2013 Microchip Technology Inc.
6.2 Package Marking
Figure 6.7 CAP1296-1 Package Marking
BOTTOM
LINE 1: Device code, first 2 of last 6
digits of lot number
LINE 2: Last 4 digits of lot number
TOP
e4
PIN 1
BOTTOM MARKING IS NOT ALLOWED
2 9 L L
L L L L
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 65
Appendix A Device Delta
A.1 Delta from CAP1106-1 to CAP1296-1
The CAP1296 is pin- and register-compatible with the CAP1106, with the exception of the ALT_POL
bit.
1. Revision ID set to 00h.
2. Added Power Button feature (see Section 4.6, "Power Button").
3. Added ACAL_FAIL bit to flag analog calibration failures (see Section 5.2, "Status Registers") and
ACAL_FAIL_INT bit to control analog calibration failure interrupts (see Section 5.6, "Configuration
Registers").
4. Added BC_OUT bit to flag calibration failures regarding base counts out of limit (see Section 5.2,
"Status Registers") and BC_OUT_RECAL and BC_OUT_INT bit to control base count out of limit
behavior and interrupts (see Section 5.6, "Configuration Registers"). Added Base Count Out of
Limit Register to indicate which sensor inputs have base counts outside the operating range (see
Section 5.18, "Base Count Out of Limit Register").
5. New Combo state has been added whi ch allo ws some sensors programmed to use the Acti ve state
settings and other sensors programmed to use the Standby state settings to function at the same
time (see Section 4.3.1.3, "Combo State Sensing Settings").
6. Added an option for a signal guard that is overloaded with the CS2 pin. This signal guard is
configured to power a ground shield for improved signal in certain applications (see Section 4.5.1,
"Signal Guard").
7. Increased supply voltage range for 5V operation.
8. Increased operating temperature range from 0°C - 85°C to -40°C to 125°C.
9. Removed ALERT pin configuration (ALT_POL bit).
10. Register additions are shown in Table A.1, "Register Delta".
Table A.1 Register Delta
ADDRESS REGISTER DELTA DELTA DEFAULT
00h
Page 30 Added bits - Main
Control Register Added C_GAIN[1:0] and COMBO bits.
Changed function of GAIN[1:0] bits if
COMBO bit is set. 00h
02h
Page 32 Added bits - General
Status Register
Added bit 4 PWR for new Powe r Button
feature. Added bit 5 ACAL_FAIL to
indicate analog calibration fa ilure. Added
bit 6 BC_OUT. 00h
26h
Page 42
Renamed Calibration
Activate and Status
Register and added
functionality
In addition to forcing a calibration, the
register also indicates the status of
calibration for each sensor input. 00h
29h
Page 45 New - Signal Guard
Enable Register new register for Signal Guard feature 00h
2Eh
Page 48 New - Base Count Out
of Limit Register new register for calibration status 00h
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 66 2013 Microchip Technology Inc.
44h
Page 36 Added and removed
bits - Configuration 2
Register
Added bit 1 ACAL_FAIL_INT. Added bit 4
BC_OUT_INT. Changed bit 6 from
ALT_POL to BC_OUT_RECAL. 40h
60h
Page 55 New - Power Button
Register new register for Power Button feature 00h
61h
Page 56 New - Power Button
Configuration Register new register for configuring the Power
Button feature 00h
80h
Page 58 Added - Calibration
Sensitivity Config 1 new register for proximity 00h
81h
Page 58 Added - Calibration
Sensitivity Config 2 new register for proximity 00h
FDh
Page 58 Changed - Product ID New product ID for CAP1296-1 69h
FFh
Page 59 Changed - Revision
Register Revision changed. 00h
Table A.1 Register Delta (continued)
ADDRESS REGISTER DELTA DELTA DEFAULT
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
2013 Microchip Technology Inc. DS01569A-page 67
Revision History
Table 6.1 Revision History
REVISION LEVEL AND
DATE SECTION/FIGURE/ENTRY CORRECTION
CAP1296 Revision A replaces the previous SMSC version Revision 1.0
6-Channel Capacitive Touch Sensor with Proximity Detection & Signal Guard
Datasheet
DS01569A-page 68 2013 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
• Microchip products meet the specification contained in their particular Microchip Data Sheet.
• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
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ISBN: 9781620774472
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