SX8656IWLTRT - SEMTECH INTERNATIONAL

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

ENERAL

ESCRIPTION

The SX8654, SX8655 and SX8656 belong to a family

of high performance haptics enabled 4/5-wire

resistive touch screen controller with proximity

detection, optimized for hand held applications such

as mobile phones, portable music players, game

machines, point-of-sales terminal and other

consumer and industrial applications. They feature a

wide input supply range from 2.3V to 3.6V.

The controller computes touch screen X-Y

coordinates and touch pressure with a precision, low

power 12-bit analog-digital converter. On-chip data

averaging processing algorithms can be activated to

reduce host activity and suppress system noise. The

processing core features low power modes which

intelligently minimize current in operation as well as in

automatic shut-down.

A capacitive proximity detection circuit has been

integrated into the SX8654 and SX8656 to enable

host controlled power management for battery

applications. Proximity detection above 5 cm is

possible using either the resistive touch screen as the

sensor or with a single conductive plate, with

communication to the host via the serial interface.

The SX8654 and SX8655 also integrate a haptics

motor driver for Linear Resonant Actuator (LRA) and

Eccentric Rotating Mass (ERM) micro motors with up

to 250mA drive current. Haptics control can be

performed using either an external PWM signal or the

I2C serial interface, providing simple host interfacing

and minimizing its I/O requirement.

Integrated very high ESD protection, of up to ±15kV

on display inputs not only saves cost and board area,

but also increases application reliability.

The three devices have an ambient operating

temperature range of -40°C to +85°C, and are offere d

in both a 4mm x 4mm, 20-lead QFN package and

2.07mm x 2.07mm 19-lead CSP package for space-

conscious applications.

YPICAL

PPLICATIONS

• Game Machines, Portable Music Players

• Mobile Phones

• DSC, DVR, Phones

• POS/POI Terminals

• Touch-Screen Monitors

RDERING

NFORMATION

RODUCT

EATURES

• Low Voltage Operation

 2.3V to 3.6V Supply

 Integrated Low Drop Out (LDO) Regulator

• Low Power Consumption

 30uA@2.3V 8ksps (ESR)

 0.4uA Shut-Down Current

• 4/5-Wire Touchscreen Interface

 Precision, Ratiometric 12-bit ADC

 Up to 5000 (X-Y) coordinates/second (c/s)

 Programmable Digital Filtering/Averaging

 Touch Pressure Measurement (4-Wire)

 Programmable Operating Mode (Manual,

Pen Detect, Pen Trigger)

• Capacitive Proximity Sensing (SX8654/56)

 No Additional Components Required

 Uses Resistive Touchscreen or a Simple

Conductive Area as the Sensor

 >5 cm Detection Distance

 8uA @ 200ms Scan Period

 Fully Programmable (Sensitivity, etc)

• Haptics Driver for LRA and ERM (SX8654/55)

 Haptics Waveform Generation Control (I2C

or PWM Input)

 Short Circuit Protection

 Early Warning and Over-Temperature

Monitoring and Protection

• 400kHz I2C Serial Interface

• Several Host Operating Modes Available

 Maskable Interrupt Output (NIRQ)

 Real-time Events Monitoring (AUX1-3)

 Polling (I2C)

• Hardware, Software, and Power-On Reset

• -40°C to +85°C Operating Temperature Range

• 15kV HBM & IEC ESD Protection

• Small Footprint Packages

• Pb & Halogen Free, RoHS/WEEE compliant

I2C

NRST

NIRQ

SX8654

Host

Controller

TOUCHSCREEN

CONTROL

PROXIMITY SENSING

HAPTICS DRIVER

Part Number Package Marking

SX8654IWLTRT QFN-20

SX8654ICSTRT WLCSP-19 CVBA

SX8655IWLTRT QFN-20

SX8655ICSTRT WLCSP-19 RB2A

SX8656IWLTRT QFN-20

SX8656ICSTRT WLCSP-19 RC95

SX8654EVK Evaluation Kit -

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

Table of Contents

ENERAL

ESCRIPTION

..................................................................................................................... 1

YPICAL

PPLICATIONS

..................................................................................................................... 1

RDERING

NFORMATION

................................................................................................................... 1

RODUCT

EATURES

.................................................................................................................. 1

ENERAL DESCRIPTION

............................................................................................................ 4

1.1

Marking Information 4

1.1.1

SX8654 4

1.1.2

SX8655 4

1.1.3

SX8656 4

1.2

Pin Diagrams 5

1.2.1

QFN Package 5

1.2.2

CSP Package 5

1.3

Pin Description 6

1.4

Block Diagram 7

LECTRICAL

HARACTERISTICS

............................................................................................... 9

2.1

Absolute Maximum Ratings 9

2.2

Thermal Characteristics 9

2.3

Electrical Specifications 9

YPICAL

PERATING

HARACTERISTICS

............................................................................... 12

OUCHSCREEN

NTERFACE

..................................................................................................... 13

4.1

Introduction 13

4.2

Coordinates Measurement 14

4.2.1

4-wire Touchscreen 14

4.2.2

5-wire Touchscreen 15

4.3

Pressure Measurement (4-wire only) 15

4.3.1

Bias Time (POWDLY) 16

4.4

Pen Detection 16

4.5

Digital Processing 17

4.6

Host Operation 19

4.6.1

Overview 19

4.6.2

Manual Mode (MAN) 19

4.6.3

Pen Detect Mode (PENDET) 20

4.6.4

Pen Trigger Mode (PENTRG) 20

4.6.5

Maximum Throughput vs. TOUCHRATE setting 21

ROXIMITY

ENSING

NTERFACE

(SX8654/56)....................................................................... 23

5.1

Introduction 23

5.2

Analog Front-End (AFE) 24

5.2.1

Capacitive Sensing Basics 24

5.2.2

AFE Block Diagram 25

5.2.3

Capacitance-to-Voltage Conversion (C-to-V) 26

5.2.4

Shield Control 26

5.2.5

Offset Compensation 26

5.2.6

Analog-to-Digital Conversion (ADC) 27

5.3

Digital Processing 27

5.3.1

Overview 27

5.3.2

PROXRAW Update 28

5.3.3

PROXUSEFUL Update 29

5.3.4

PROXAVG Update 30

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Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

5.3.5

PROXDIFF Update 32

5.3.6

PROXSTAT Update 32

5.4

Host Operation 33

5.4.1

General Description 33

5.4.2

Proximity Sensing vs Touch Operations 33

5.4.3

Minimum Scan Period (i.e. PROXSCANPERIOD) 35

APTICS

NTERFACE

(SX8654/55) .......................................................................................... 36

6.1

Introduction 36

6.2

ERM Load 36

6.2.1

Introduction 36

6.2.2

PWM Mode 37

6.2.3

I2C Mode 37

6.3

LRA Load 37

6.3.1

Introduction 37

6.3.2

PWM Mode 38

6.3.3

I2C Mode 38

6.4

Short-Circuit Protection 38

EMPERATURE

ENSOR

.......................................................................................................... 39

NTERRUPT

(NIRQ).................................................................................................................. 40

8.1

Introduction 40

8.2

Registers Overview 40

8.2.1

RegIrqMsk 40

8.2.2

RegIrqSrc 40

8.2.3

RegStat 40

8.3

Host Procedure 40

UXILIARY

INS

(AUX1/AUX2/AUX3)...................................................................................... 41

ESET

...................................................................................................................................... 42

10.1

Hardware (POR and NRST) 42

10.2

Software (RegReset) 42

10.3

ESD Event (RESETSTAT) 42

I2C

NTERFACE

........................................................................................................................ 43

11.1

Introduction 43

11.2

I2C Address 43

11.3

Write Register 43

11.4

Read Register 44

11.5

Write Command (Touchscreen Interface) 44

11.6

Read Channel (Touchscreen Interface) 45

EGISTERS

ETAILED

ESCRIPTION

...................................................................................... 47

PPLICATION

NFORMATION

................................................................................................... 59

13.1

Typical Application Circuit 59

13.2

External Components Recommended Values 59

ACKAGING

NFORMATION

..................................................................................................... 60

14.1

QFN Package 60

14.2

CSP Package 61

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

1 G

ENERAL DESCRIPTION

1.1 Marking Information

1.1.1 SX8654

Figure 1 – Marking Information – QFN(left) – CSP(right)

1.1.2 SX8655

Figure 2 – Marking Information – QFN(left) – CSP(right)

1.1.3 SX8656

Figure 3 – Marking Information – QFN(left) – CSP(right)

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Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

1.2 Pin Diagrams

1.2.1 QFN Package

Figure 4 – Pin Diagram – QFN

Note that haptics pins (MVDD, MGND, MIN, MOUTN, MOUTP) are not used on SX8656. (Cf. § 1.3)

1.2.2 CSP Package

Figure 5 – Pin Diagram - CSP

Note that haptics pins (MVDD, MGND, MIN, MOUTN, MOUTP) are not used on SX8656. (Cf. § 1.3)

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Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

1.3 Pin Description

Name Type Description

VDD P Main Power Supply

GND P Main Ground

VREG P Internal Regulator Output (must be connected to an external capacitor; see § 13)

MVDD P SX8654/55 : Haptics Motor Power Supply

SX8656 : Not used, connect to VDD.

MGND P SX8654/55 : Haptics Motor Ground (must be electrically connected to GND)

SX8656 : Not used, connect to GND.

MOUTP AO SX8654/55 : Haptics Motor Positive Drive

SX8656 : Not used, do not connect.

MOUTN AO SX8654/55 : Haptics Motor Negative Drive

SX8656 : Not used, do not connect.

MIN DI SX8654/55 : Haptics Motor PWM/Clock Input

SX8656 : Not used, connect to GND.

X+/BR A • 4-wire Touchscreen : X+ Electrode

• 5-wire Touchscreen : Bottom Right (BR) Electrode

Y+/TR A • 4-wire Touchscreen : Y+ Electrode

• 5-wire Touchscreen : Top Right (TR) Electrode

X-/TL A • 4-wire Touchscreen : X- Electrode

• 5-wire Touchscreen : Top Left (TL) Electrode

Y-/BL A • 4-wire Touchscreen : Y- Electrode

• 5-wire Touchscreen : Bottom Left (BL) Electrode

AUX1/WIPER D/A • 4-wire Touchscreen : First Programmable Auxiliary Function (see § 9)

• 5-wire Touchscreen : WIPER Electrode

AUX2 D/A Second Programmable Auxiliary Function (see § 9)

AUX3 D/A Third Programmable Auxiliary Function (see § 9)

ADDR DI I2C Address Selection (QFN only, internally connected to GND on CSP)

SCL DI I2C Clock Input

SDA DIO I2C Data Input/Output

NIRQ DO Interrupt Output (active low)

NRST DI Reset Input (active low)

A/D/I/O/P: Analog/Digital/Power/Input/Output

Table 1 – Pin Description

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

1.4 Block Diagram

Figure 6 – SX8654 Block Diagram

Figure 7 – SX8655 Block Diagram

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

Figure 8 – SX8656 Block Diagram

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Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

2 E

LECTRICAL

HARACTERISTICS

2.1 Absolute Maximum Ratings

Stress above the limits listed in the following table may cause permanent failure. Exposure to absolute ratings for

extended time periods may affect device reliability. The limiting values are in accordance with the Absolute

Maximum Rating System (IEC 134). All voltages are referenced to ground (GND).

Symbol Description Conditions Min Max Unit

VABS Voltage applied on any pin - 0.5 3.9 V

X+/BR, Y+/TR, X-/TL,

Y-/BL, VDD, MVDD +/-15

(1)

, +/-8

(2)

VESDHBM Electrostatic handling

Human Body Model (HBM) Other pins +/-8

(2)

X+/BR, Y+/TR, X-/TL,

Y-/BL, VDD, MVDD +/-1

VESDCDM Electrostatic handling

Charged Device Model (CDM) Other pins +/-1 kV

X+/BR, Y+/TR, X-/TL,

Y-/BL, VDD, MVDD +/-250

VESDMM Electrostatic handling

Machine Model (MM) Other pins +/-250 V

VESDCD Electrostatic handling

Contact Discharge (CD) X+/BR, Y+/TR, X-/TL,

Y-/BL, VDD, MVDD +/-15 kV

TAMB Operating ambient temperature

-40 +85 °C

TJUN Operating junction temperature

-40 +125 °C

TSTOR Storage temperature -55 +150 °C

ILAT Latch-up current

(3)

+/-100 mA

(1) Tested to TLP (10A)

(2) Tested to JEDEC standard JESD22-A114

(3) Tested to JEDEC standard JESD78

Table 2 - Absolute Maximum Ratings

2.2 Thermal Characteristics

Symbol Description Conditions Min Max Unit

θJAQ Thermal Resistance Junction – Ambient

QFN package - - 30.5 °C/W

θJAW Thermal Resistance Junction – Ambient

WLCSP package - - 29 °C/W

Table 3 – Thermal Characteristics

2.3 Electrical Specifications

Table below applies to full supply voltage and temperature range, unless otherwise specified. Typical values are

given for T

= +25°C, VDD=VDDM=3.3V.

Symbol Description Conditions Min Typ. Max Unit

Supply

VDD Main supply voltage - 2.3 - 3.6 V

OFF

(MAN mode, no command,

HAPT OFF)

- 0.4 0.75

WAIT

(PENDET/TRG mode, pen up,

PROX OFF, HAPT OFF)

- 1.7 -

TOUCH1

(PENTRG mode, pen down

, X+Y,

RATE=4kcps, Nfilt=1,

POWDLY=0.5us, touchscreen

current excluded, HAPT OFF,

VDD=2.3V)

- 30 -

IDD Main supply current

TOUCH2

(PENTRG mode, pen down

, X+Y,

RATE=3kcps, Nfilt=7,

POWDLY=0.5us, touchscreen

current excluded, HAPT OFF)

- 120 160

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Resistive Touchscreen Controller with Proximity Sensing

Symbol Description Conditions Min Typ. Max Unit

PROX

(PENDET/TRG mode, pen up,

TOUCHRATE=80cps, PROX

ON,

SCANPERIOD=200ms,

HIGHIM=ON,

SENSITIVITY=Max,

FREQ=150kHz, BOOST=OFF,

HAPT OFF)

- 8 20

HAPT

(MAN mode, no command,

LRA-PWM mode,

MIN= 44.8kHz/50%,

GAIN = Max,

BW = 100, MOUTP/N floating,

Squelch=011)

- 115 145

MVDD Haptics supply voltage - VDD - 3.6 V

OFF - 0.01 1 µA

MIDD Haptics supply current SQUELCH

(LRA-PWM mode,

MIN= 44.8kHz/50%, GAIN =

Max,

BW = 100, MOUTP/N floating,

Squelch=011)

- 6 10 µA

Digital I/Os (ADDR, SCL, SDA, NRST, NIRQ, AUX1, AUX2, AUX3, MIN)

SCL, SDA, NRST 0.8*VDD

- 3.6

VIH High level input voltage Other pins 0.8*VDD

- VDD+0.2

VIL Low level input voltage - -0.3 - 0.8 V

ILEAK Input leakage current - -1 - 1 µA

CI Input capacitance - - 5 - pF

VOH High level output voltage IOH = 4mA 0.8*VDD

- - V

VOL Low level output voltage IOL = 4mA - - 0.4 V

VPULL External pull-up voltage SCL, SDA, NRST, NIRQ - - 3.6 V

Haptics Interface

IDRV Maximum drive current

(MOUTP/MOUTN) MVDD = 3.6V - 250 - mA

VOFF Output squelch differential error

(from 0V ideal)

LRA or ERM, PWM or I2C,

AmplitudeCode within squelch

range, GAIN = Max, BW = 100,

MOUTP/N floating, Squelch=011

(1)

0 0

(1)

VERR Output differential error

(from 1.135V ideal)

LRA or ERM, I2C,

AmplitudeCode = +127 (Max)

GAIN = Min, BW = 100,

MOUTP/N floating

125

(2)

0 125

(2)

VDRV Drive voltage (MOUTP/MOUTN) - - - VDDM V

VDROP Drop voltage (MOUTP/MOUTN) From MVDD/MGND,

@250mA - - 150 mV

ISHORT Short-circuit detection current Measured @MIDD - 300 - mA

FMINC Motor input (MIN) frequency in

I2C mode 40-60% duty cycle - - 50 MHz

HAPTRANGE = 0 12.8 - 25.6 kHz

FMINP Motor input (MIN) frequency in

PWM mode HAPTRANGE = 1 25.6 - 51.2 kHz

DCMIN Motor input (MIN) duty cycle in

PWM mode 2 - 98 %

TWRNG

Warning temperature - 120 -

TALRM Alarm temperature Junction temperature - 155 - °C

Touchscreen Interface

ARES ADC resolution 12 - - bits

AOFF ADC offset - ± 1 -

AGE ADC gain error At full scale - 0.5 -

ADNL ADC differential non-linearity - ± 1 -

AINL ADC integral non-linearity - ± 1.5 -

LSB

RBIAS Biasing resistance - 5 - Ω

Proximity Sensing Interface

CDC External capacitance to be

compensated - - - 300 pF

PROX

Scan period (reaction time) Programmable - 200 - ms

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Wire

Resistive Touchscreen Controller with Proximity Sensing

Symbol Description Conditions Min Typ. Max Unit

Reset

VPOR Power-On-Reset voltage Cf. § 10 - 1.3 - V

RESET

Reset time after POR Cf. § 10 - - 1 ms

PULSE

Reset pulse from host uC Cf. § 10 1 - - us

I2C Interface

SCL

SCL clock frequency - - - 400

kHz

HD;STA

Hold time (repeated) START

condition - 0.6 - - µs

LOW

LOW period of the SCL clock - 1.3 - - µs

HIGH

HIGH period of the SCL clock - 0.6 - - µs

SU;STA

Set-up time for a repeated

START condition - 0.6 - - µs

HD;DAT

Data hold time - 0 - - µs

SU;DAT

Data set-up time - 100 - - ns

Rise time of both SDA and SCL - 20+0.1C

- 300 ns

Fall time of both SDA and SCL - 20+0.1C

- 300 ns

SU;STO

Set-up time for STOP condition - 0.6 - - µs

BUF

Bus free time between a STOP

and START condition - 1.3 - - µs

Capacitive load for each bus line - - - 400 pF

Pulse width of spikes

suppressed by the input filter Up to 0.3xVDD from

GND, down to 0.7xVDD

from VDD 50 - - ns

Miscellaneous

FOSCL Low frequency internal oscillator - - 32 -

kHz

FOSCH High frequency internal oscillator - - 1.8 -

MHz

(1)

Guaranteed by design.

(2)

PWM mode can introduce an additional error of 2.5% of full scale.

Table 4 – Electrical Specifications

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Wire

Resistive Touchscreen Controller with Proximity Sensing

3 T

YPICAL

PERATING

HARACTERISTICS

Conditions as defined in § 2.3, T

= +25°C, VDD=VDDM=3.3V unless otherwise specified.

IDD_OFF vs VDD vs TEMP

2.00E-07

2.20E-07

2.40E-07

2.60E-07

2.80E-07

3.00E-07

3.20E-07

3.40E-07

3.60E-07

3.80E-07

4.00E-07

2.3 2.5 2.7 2.9 3.1 3.3 3.5

VDD(V)

IDD(A)

25°C

85°C

-40°C

IDD_WAIT vs VDD vs TOUCHRATE

2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6

VDD(V)

IDD(uA)

10cps

80cps

2000cps

5000cps

IDD_PROX vs SCANPERIOD vs SENSITIVITY

0 100 200 300 400 500 600 700 800

SCANPERIOD(ms)

IDD_PROX(uA)

0(Min)

7(Max)

IDD_HAPT vs VDD vs TEMP

0.0001

0.00011

0.00012

0.00013

0.00014

0.00015

0.00016

0.00017

0.00018

0.00019

0.0002

2.3 2.5 2.7 2.9 3.1 3.3 3.5

VDD(V)

IDD(A)

25°C

85°C

-40°C

MIDD_OFF vs MVDD vs TEMP

0.00E+00

5.00E-09

1.00E-08

1.50E-08

2.00E-08

2.50E-08

3.00E-08

3.50E-08

4.00E-08

4.50E-08

5.00E-08

2.3 2.5 2.7 2.9 3.1 3.3 3.5

MVDD(V)

MIDD(A)

25°C

85°C

-40°C

MIDD_SQUELCH vs MVDD vs TEMP

5.00E-06

6.00E-06

7.00E-06

8.00E-06

9.00E-06

1.00E-05

2.3 2.5 2.7 2.9 3.1 3.3 3.5

MVDD(V)

IDD(A)

25°C

85°C

-40°C

VERR vs GAIN vs MVDD

0.02

0.03

0.04

0.05

0.06

0.07

0.08

GAIN

VOFF(V)

2.3V

3.3V

3.6V

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Resistive Touchscreen Controller with Proximity Sensing

4 T

OUCHSCREEN

NTERFACE

4.1 Introduction

The purpose of the touchscreen interface is to measure and extract touch information like coordinates and

pressure. This is done in two steps, first an ADC measures the analog signal coming from the screen, and then

digital processing is performed to consolidate the data.

As illustrated below the chip’s touchscreen interface is compatible with both 4-wire and 5-wire touchscreens.

Touchscreen type is defined by parameter TSTYPE.

Figure 9 – Touchscreen Interface Overview

A 4-wire resistive touch screen consists in two (resistive) conductive sheets separated by an insulator when not

pressed. Each sheet is connected through 2 electrodes at the border of the sheet. When a pressure is applied

on the top sheet, a connection with the lower sheet is established.

Figure 10 – 4-wire Touchscreen

A 5-wire resistive touch screen consists in two (resistive) conductive sheets separated by an insulator when not

pressed. 4 electrodes are connected on the 4 corners of the bottom conductive sheet. They are referred as Top

Left (TL), Top Right (TR), Bottom Left (BL) and Bottom Right (BR).

The fifth wire (WIPER) is used for sensing the top sheet voltage. When a pressure is applied on the top sheet, a

connection with the lower sheet is established.

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Haptics Enabled 4/5-

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Resistive Touchscreen Controller with Proximity Sensing

Higher reliability and better endurance are the advantages of 5-wire touchscreens but they do not allow pressure

measurement

Figure 11 – 5-wire Touchscreen

4.2 Coordinates Measurement

4.2.1 4-wire Touchscreen

The electrode plates are internally connected through terminals X+, X- and Y+, Y- to an analog to digital

converter (ADC) and a reference voltage (Vref). The resistance between the terminals X+ and X- is defined by

Rxtot. Rxtot will be split in 2 resistors, R1 and R2, in case the screen is touched. Similarly, the resistance

between the terminals Y+ and Y- is represented by R3 and R4. The connection between the top and bottom

sheet is represented by the touch resistance (RT).

In order to measure the Y coordinate, the top resistive sheet (Y) is biased with a voltage source (Vref). Resistors

R3 and R4 determine a voltage divider proportional to the Y position of the contact point. Since the converter has

a high input impedance, no current flows through R1 (and RT) so that the voltage X+ at the converter input is

given by the voltage divider created by R3 and R4.

The X coordinate is measured in a similar fashion with the bottom resistive sheet (X) biased to create a voltage

divider by R1 and R2, while the voltage on the top sheet is measured through R3.

The resistance RT is the resistance obtained when a pressure is applied on the screen. RT is created by the

contact area of the X and Y resistive sheet and varies with the applied pressure.

Figure 12 – 4-wire Touchscreen Coordinates Measurement

The X and Y positions output by the ADC correspond to the formulas below:

Xpos 4095 R2

R1 R2+

---------------------

⋅

=Ypos 4095 R4

R3 R4+

---------------------

⋅

4095 corresponds to the max output value of the ADC (12 bits => 2

– 1).

For example, a touch in the center of the screen will output (Xpos, Ypos) = ~(2048, 2048)

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4.2.2 5-wire Touchscreen

5-wire touchscreen coordinates measurement is performed similarly by biasing opposite corner pairs in either X

or Y directions on the lower panel, and converting the voltage appearing on the wiper panel with the ADC.

Figure 13 – 5-wire Touchscreen Coordinates Measurement

The X and Y positions output by the ADC correspond to the formulas below:

Xpos 4095 R2

R1 R2+

---------------------

⋅

=Ypos 4095 R4

R3 R4+

---------------------

⋅

4095 corresponds to the max output value of the ADC (12 bits => 2

– 1).

For example, a touch in the center of the screen will output (Xpos, Ypos) = ~(2048, 2048)

4.3 Pressure Measurement (4-wire only)

The pressure measurement consists in extracting the touch resistance R

via two additional setups z1 and z2

illustrated below. The smaller R

, the more common touched surface there is between top and bottom plates

and hence the more “pressure” there is by the user.

Figure 14 – Pressure Measurement

The z1 and z2 values output by the ADC correspond to the formulas below:

z1 4095 R4

R1 R4 R

+ +

----------------------------------

⋅

= z2 4095 R4 Rt+

R1 R4 R

+ +

----------------------------------

⋅

The X and Y total sheet resistance (Rxtot = R1+R2, Rytot = R3+R4) are known from the touch screen supplier.

R4 is proportional to the Y coordinate and its value is given by the total Y plate resistance Rytot multiplied by the

fraction of the Y position over the full coordinate range.

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Rxtot R1 R2+=

Rytot R3 R4+=

R4 Rytot Ypos

4095

-------------

⋅

Re-arranging z1 and z2 gives:

R4 z2

------ 1–

⋅

This finally results in:

Rytot Ypos

4095

------------- z2

------ 1

–

⋅ ⋅

The touch resistance calculation above hence requires three channel measurements (Ypos, z2 and z1) and one

specification data (Rytot).

An alternative calculation method is using Xpos, Ypos, one z channel and both Rxtot and Rytot as shown in the

next calculations.

R1 is inversely proportional to the X coordinate:

R1 Rxtot 1 Xpos

4095

-------------–

⋅

Substituting R1 and R4 into z1 and rearranging terms gives:

Rytot Y

⋅pos

4095

--------------------------------- 4095

------------ 1– Rxtot 1 Xpos

4095

-------------–

⋅

–

⋅

Please note that the chip only outputs z1, z2, etc. The calculation of R

itself with the formulas above must be

performed by the host.

4.3.1 Bias Time (POWDLY)

In order to perform correct measurements, some time must be given for the touch screen to reach a proper Vref

bias level before the conversion is actually performed. It is a function of the PCB trace resistance connecting the

chip to the touchscreen and also the capacitance of the touchscreen. If tau is this RC time constant, then

POWDLY duration must be programmed to 10 tau to reach 12 bits accuracy.

Adding a capacitor from the touch screen electrodes to ground may also be used to minimize external noise (if

the touchscreen is used as the proximity sensor, make sure you do not exceed the maximum capacitive load for

required for proper proximity sensing operation). The low-pass filter created with the capacitor may increase

settling time requirement. Therefore, POWDLY can be used to stretch the acquisition period and delay

conversion appropriately.

POWDLY can be estimated by the following formula:

PowDly 10 Rtouch Ctouch

4.4 Pen Detection

The pen detection circuitry is used both to detect a user action and generate an interrupt or start an acquisition in

PENDET and PENTRG mode respectively. Doing pen detection prior to conversion avoids feeding the host with

dummy data and saves power. Pen detection is also used to disable and resume proximity sensing. For more

details on pen detection usage please refer to § 4.6.

A 4-wire touchscreen will be powered between X+ and Y- through a resistor RPNDT so no current will flow as

long as no pressure is applied to the surface (see figure below). When a touch occurs, a current path is created

bringing X+ to the level defined by the resistive divider determined by RPNDT and the sum of R1, RT and R4.

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Figure 15 – 4-wire Touchscreen Pen Detection

When using a 5-wire touchscreen, the pen detection pull-up resistor R

PNDT

and digital comparator continue to

monitor the X+/BR pin as in 4-wire mode. The top panel is grounded via the WIPER pin to provide the grounding

path for a screen touch event. When a touch occurs, a current path is created and will bring BR to the level

defined by the resistive divider determined by R

PNDT

and the sum of R1, RT and RW.

Figure 16 – 5-wire Touchscreen Pen Detection

PNDT

can be configured to 4 different values to accommodate different screen resistive values.

PNDT

should be set to a value greater than 7x(Rxtot + Rytot), it is recommended to set it to max value.

Pen detection uses a bias time of POWDLY/8 (digital comparator => less precision required vs analog

conversion). Increasing POWDLY can improve the detection on panels with high resistance.

A pen touch will set the PENSTAT bit of the RegStat register which will generate an interrupt if enabled in

RegIrqMsk.

A pen release will reset PENSTAT bit of the RegStat register which will generate an interrupt if enabled in

RegIrqMsk.

4.5 Digital Processing

The chip offers 4 types of data processing which allows the user to make trade-offs between data throughput,

power consumption and noise rejection.

The parameter FILT is used to select the filter order Nfilt. The noise rejection will be improved with a high order

to the detriment of power consumption. Each channel can be sampled up to 7 times and then processed to get a

single consolidated coordinate.

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∑

−

=−

⋅≈

iinn

Figure 17 – Digital Processing Block Diagram

FILT Nfilt Function

0 1

No average.

1 3

---

4079

4095

------------ s

n 1–

n 2–

+ +

( )

⋅

3 ADC samples are averaged.

2 5

cn1

--- 4079

4095

------------

⋅snsn 1– sn 2– sn 3– sn 4–

+ + + +

( )

5 ADC samples are averaged.

3 7

max1

max2

min1

min2

≥ ≥ ≥ ≥ ≥ ≥

---

4079

4095

------------

⋅s

+ +

( )

7 ADC samples are sorted and the 3 center samples are averaged.

Table 5 – Digital Processing Functions

The parameter SETDLY sets the settling time between the consecutive conversions of the same channel.

Figure 18 – POWDLY and SETDLY (FILT=2)

In most applications, SETDLY can be set to minimum (0.5us). However, in some particular applications where

an accuracy of 1LSB is required SETDLY may need to be increased.

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4.6 Host Operation

4.6.1 Overview

The chip has three operating modes that are configured using the I2C as defined in § 11 :

 Manual (command ‘MAN’ and TOUCHRATE = 0).

 Pen detect (command ‘PENDET’ and TOUCHRATE > 0).

 Pen trigger (command ‘PENTRG’ and TOUCHRATE > 0).

At power-up the chip is set in manual mode.

4.6.2 Manual Mode (MAN)

In manual mode (MAN) the touchscreen interface is stopped and conversions must be manually triggered by the

host using SELECT and CONVERT command.

When a command is received, the chip executes the associated tasks listed in table below and waits for the next

command. It is up to the host to sequence all actions.

Pen detection is performed after each CONVERT command and if pen is not detected, no touch operation is

performed. Following figures assume pen down. PENSTAT is not updated in MAN mode.

To enter MAN mode the host must send the MAN command and then set TOUCHRATE = 0.

Command Actions

CONVERT(CHAN)

Select and bias CHAN

Wait for the programmed settling time (POWDLY)

Convert CHAN

SELECT(CHAN)

Select and bias CHAN

Table 6 – Manual Mode Commands

As illustrated in figure below the CONVERT command will bias the channel, wait for the programmed settling

time (POWDLY), and run the conversion.

Figure 19 – Manual Mode – CONVERT Command (CHAN = Y; PROXSCANPERIOD = 0)

When the CONVERT command is used with CHAN=SEQ, multiple channels as defined in RegChnMsk are

sampled. In this case, each channel will be sequentially biased during POWDLY before a conversion is started.

At the end of each channel conversion the bias is automatically removed.

Figure 20 – Manual Mode – CONVERT Command (CHAN = SEQ = [X;Y]; PROXSCANPERIOD = 0)

I2C

Channel Bias

CONVERT(SEQ)

Channel Conversion

READ CHANNEL

POWDLY POWDLY

NIRQ (RegIrqMsk[3]=1)

CONVSTAT

I2C

Channel Bias

CONVERT(Y)

Channel Conversion

READ CHANNEL

NIRQ (RegIrqMsk[3]=1)

POWDLY

CONVSTAT

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In case the range of POWDLY settings available is not enough to cover the required settling time, one can use

the SELECT command first to bias the channel, and then send the CONVERT command hence extending bias

time. SELECT command cannot be used with CHAN=SEQ.

Figure 21 – Manual Mode – SELECT command (CHAN = Y; PROXSCANPERIOD = 0)

At the end of the conversion(s) bit CONVSTAT will be reset which will trigger NIRQ falling edge (if enabled in

RegIrqMsk). Host can then read channel data which will release NIRQ.

Please note that when the SELECT command is used, the channel is converted whatever the pen status (no pen

detection performed).

4.6.3 Pen Detect Mode (PENDET)

In pen detect mode (PENDET) the chip will only run pen detection (continuously when pen is up, regularly as

defined by TOUCHRATE when pen is down) and update PENSTAT bit in RegStat to be able to generate an

interrupt (NIRQ) upon pen detection and/or release. No (touch) conversion is performed in this mode.

To enter PENDET mode the host must set TOUCHRATE > 0 and then send PENDET command.

To quit PENDET mode and stop the touchscreen interface the host must enter MAN mode.

Figure 22 – Pen Detect Mode (RegIrqMsk[3:2] = 11 ; PROXSCANPERIOD = 0)

Please note that the next pen detection is not performed as long as NIRQ is low. If the host is too slow and

doesn’t read IrqSrc before next TOUCHRATE tick, no operation is performed and this TOUCHRATE tick is

simply ignored until next one.

4.6.4 Pen Trigger Mode (PENTRG)

In pen trigger mode (PENTRG) the chip will perform pen detection (continuously when pen is up, regularly as

defined by TOUCHRATE when pen is down) and if pen is down, will be followed by a conversion as defined in

RegChanMsk. The chip will update CONVSTAT bit in RegStat and will be able to generate an interrupt (NIRQ)

upon conversion completion. The chip will also update PENSTAT bit in RegStat and will be able to generate an

interrupt (NIRQ) upon pen detection and/or release.

The PENTRG mode offers the best compromise between power consumption and coordinate throughput. To

enter PENTRG mode the host must set TOUCHRATE > 0 and then send PENTRG command. To quit PENTRG

mode and stop the touchscreen interface the host must enter MAN mode.

Idle

Pen

etection

NIRQ

I2C Read

Reg

IrqSrc

Pen Touch

Pen Release

PENSTAT

CONVSTAT

SELECT(Y)

I2C

Channel Bias

CONVERT(Y)

Channel Conversion

READ CHANNEL

POWDLY

NIRQ (RegIrqMsk[3]=1)

ctual bias time

CONVSTAT

TOUCHRATE

tick

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Figure 23 – Pen Trigger Mode (RegIrqMsk[3:2] = 10 ; PROXSCANPERIOD = 0)

Please note that to prevent data loss, the next pen detection and conversion are not performed as long as all

current channel data (i.e. channels selected in RegChanMsk) have not been read. If the host is too slow and

doesn’t read all channel data before next TOUCHRATE tick, no operation is performed and this TOUCHRATE

tick is simply ignored until next one.

4.6.5 Maximum Throughput vs. TOUCHRATE setting

In PENTRG mode the TOUCHRATE parameter is used to define the required coordinate’s throughput/rate.

However, as previously mentioned, in order for a new conversion to be performed the current conversion must

be completed and all relevant channel data must have been read by the host. If this condition is not met when

the next TOUCHRATE tick occurs, the tick is ignored and the condition checked again at the next one. This will

result in reduced actual rate vs what has been programmed in the TOUCHRATE parameter.

This is illustrated in figures below.

Figure 24 – Correct TOUCHRATE setting

Idle

Touch

Conver

sion

Pen Detection

NIRQ

Pen Touch

Pen Release

I2C Read Channel

PENSTAT

CONVSTAT

TOUCHRATE

tick

Idle

Touch

Conver

sion

Pen Detection

NIRQ

TOUCHRATE

ick

I2C Read Channel

Tconv

Tcom

Trate

Tconv+Tcom < Trate

=> Actual rate = TOUCHRATE

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Figure 25 – Incorrect (too high) TOUCHRATE setting

In order to prevent this, one can estimate the maximum throughput achievable and set TOUCHRATE parameter

accordingly. MaxThroughput = 1 / (Tconv+Tcom)

Tcom is the time between the end of conversion (ie NIRQ falling edge) and the end of channel data reading (i.e.

NIRQ rising edge). Maximum throughput implies that the host reacts “instantaneously” to NIRQ falling edge:

com

8 16 N

chan

( ) T

I2C

Tconv is the total conversion time:

Tconv us

( ) 47 Tosc

⋅N+

chan

POWDLY N

filt

1–

( ) SETDLY 21N

filt

( ) Tosc

⋅

( )

⋅

- T

I2C

is the period of the I2C clock SCL

- N

filt

= {1,3,5,7} based on the order defined for the filter FILT

- N

chan

= {1,2,3,4,5} based on the number of channels defined in RegChanMsk

- POWDLY = 0.5us to 18.19ms, settling time as defined in RegTS0

- SETDLY = 0.5us to 18.19ms, settling time when filtering as defined in RegTS2

- Tosc is the period of the internal oscillator FOSCH

Some examples of maximum throughputs achievable with an I2C running at 400kHz are given below.

Nchan Nfilt POWDLY

[us] SETDLY

[us] Tconv

[us] Tcom

[us] Total

[us] CR

[kcps] ECR

[kcps] SR

[ksps] ESR

[ksps]

2 1 0.5 0.5 51.7 100 151.7 6.6 13.2 6.6 13.2

2 3 35.5 0.5 170.6 100 270.6 3.7 7.4 11.1 22.2

2 5 2.2 0.5 152.8 100 252.8 4 8 20 40

4 3 35.5 0.5 315.0 200 515 1.9 7.6 5.7 22.8

Table 7 – Maximum Throughputs Examples

- CR = Coordinate Rate

- ECR = Equivalent Coordinate Rate = CR x N

chan

- SR = Sampling Rate = CR x N

filt

- ESR = Equivalent Sampling Rate = SR x N

chan

= CR x N

filt

x N

chan

For proper operation, the TOUCHRATE parameter should not exceed the theoretical maximum throughput CR.

Idle

Touch

Conver

sion

Pen Detection

NIRQ

TOUCHRATE

tick

Not

ready, tick ignored

I2C Read Channel

Tconv

Tcom

Trate

Trate < Tconv+Tcom < n.Trate

=> Actual rate = TOUCHRATE/n

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5 P

ROXIMITY

ENSING

NTERFACE

(SX8654/56)

5.1 Introduction

The purpose of the proximity sensing interface is to detect when a conductive object (usually a body part i.e.

finger, palm, face, etc) is in the proximity of the system. This is commonly used in power-sensitive mobile

applications to turn the screen’s LCD ON/OFF depending on user’s finger/palm/face proximity.

The chip’s proximity sensing interface is based on capacitive sensing technology and shares the ADC with the

touchscreen interface (Cf § 5.4.2). An overview is given in figure below.

Shield

Sensor Analog

Front-End

(AFE)

Digital

Processing

SX8654/56

PROXSTAT

010

Finger, palm,

face, etc

Figure 26 – Proximity Sensing Interface Overview

 The sensor can be the top layer of the touchscreen or a simple copper area on the PCB (programmable

in PROXSENSORCON). Its capacitance (to ground) will vary when a conductive object is moving in its

proximity.

 The optional shield can be the bottom layer of the touchscreen or a simple copper area on the PCB

(programmable in PROXSHIELDCON) below/under/around the sensor. It is used to protect the sensor

against potential surrounding noise sources and improve its global performance. It also brings directivity

to the sensing, for example sensing objects approaching from top only.

 The analog front-end (AFE) performs the raw sensor’s capacitance measurement and converts it into a

12 bit digital code. It also controls the shield. See § 5.2 for more details.

 The digital processing block computes the raw capacitance measurement from the AFE and extracts a

binary information PROXSTAT corresponding to the proximity status, i.e. object is “Far” or “Close”. It

also triggers AFE operations (compensation, etc). See § 5.3 for more details.

To save power since the proximity event is slow by nature, the block will be waken-up regularly at every

programmed scan period (PROXSCANPERIOD) to sense and then process a new proximity sample. The block

will be in idle mode most of the time. This is illustrated in figure below

Figure 27 – Proximity Sensing Sequencing

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5.2 Analog Front-End (AFE)

5.2.1 Capacitive Sensing Basics

Capacitive sensing is the art of measuring a small variation of capacitance in a noisy environment. As

mentioned above, the chip’s proximity sensing interface is based on capacitive sensing technology. In order to

illustrate some of the user choices and compromises required when using this technology it is useful to

understand its basic principles.

To illustrate the principle of capacitive sensing we will use the simplest implementation where the sensor is a

copper plate on a PCB but the exact same principles apply if the sensor is the touchscreen’s top plate.

The figure below shows a cross-section and top view of a typical capacitive sensing implementation. The sensor

connected to the chip is a simple copper area on top layer of the PCB. It is usually surrounded (shielded) by

ground for noise immunity (shield function) but also indirectly couples via the grounds areas of the rest of the

system (PCB ground traces/planes, housing, etc). For obvious reasons (design, isolation, robustness …) the

sensor is stacked behind an overlay which is usually integrated in the housing of the complete system. When the

touchscreen is used for sensing the overlay corresponds to the thin and flexible protection film covering the top

panel.

PCB dielectric

Ground

Cut view

Top view

PCB copper

Sensor

Overlay

Figure 28 – Typical Capacitive Sensing Implementation

When the conductive object to be detected (finger/palm/face, etc) is not present, the sensor only sees an

inherent capacitance value C

Env

created by its electrical field’s interaction with the environment, in particular

with ground areas.

When the conductive object (finger/palm/face, etc) approaches, the electrical field around the sensor will be

modified and the total capacitance seen by the sensor increased by the user capacitance C

User

. This

phenomenon is illustrated in the figure below.

Figure 29 – Proximity Effect on Electrical Field and Sensor Capacitance

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The challenge of capacitive sensing is to detect this relatively small variation of C

Sensor

User

usually contributes

for a few percents only) and differentiate it from environmental noise (C

Env

also slowly varies together with the

environment characteristics like temperature, etc). For this purpose, the chip integrates an auto offset

compensation mechanism which dynamically monitors and removes the C

Env

component to extract and process

User

only. See § 5.2.5 for more details.

In first order, C

User

can be estimated by the formula below:

is the common area between the two electrodes hence the common area between the user’s finger/palm/face

and the sensor.

is the distance between the two electrodes hence the proximity distance between the user and the system.

is the free space permittivity and is equal to 8.85 10e-12 F/m (constant)

is the dielectric relative permittivity.

When performing proximity sensing the dielectric relative permittivity is roughly equal to that of the air as the

overlay is relatively thin compared to the detection distance targeted. Typical permittivity of some common

materials is given in the table below.

Material Typical

Glass 8

FR4 5

Acrylic Glass 3

Wood 2

Air 1

From the discussions above we can conclude that the most robust and efficient design will be the one that

minimizes C

Env

value and variations while improving C

User

5.2.2 AFE Block Diagram

Figure 30 – Analog Front-End Block Diagram

Aεε

User

⋅

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5.2.3 Capacitance-to-Voltage Conversion (C-to-V)

PROXSENSORCON defines which pin will act as the sensor during proximity sensing operations. In the typical

case, the touchscreen top layer is used as the sensor (exact pin/electrode depends on screen type/structure).

Else, the sensor can also be “external”, i.e. connected to AUX2.

The sensitivity of the interface is defined by PROXSENSITIVITY; for obvious power consumption reasons it is

recommended to set it as low as possible.

As a last resort and only if the sensor is “external”, PROXBOOST can be set to allow higher sensitivity if needed.

PROXFREQ defines the operating frequency of the interface and should be set as high as possible for power

consumption reasons.

If needed, PROXHIGHIM enables a high noise immunity mode at the expense of increased power consumption.

5.2.4 Shield Control

PROXSHIELDCON defines which pin will act as the shield during proximity sensing operations. In the typical

case, the shield will usually be the touchscreen bottom layer (exact pin/electrode depends on screen

type/structure). Else, the shield can also be “external”, ie a simple copper area on the PCB connected to AUX3.

5.2.5 Offset Compensation

Offset compensation consists in performing a one time measurement of C

Env

and subtracting it to the total

capacitance C

Sensor

in order to feed the ADC with the closest contribution of C

User

only.

Figure 31 – Offset Compensation Block Diagram

The ADC input C

User

is the total capacitance C

Sensor

to which C

Env

is subtracted.

There are five possible compensation sources which are illustrated in the figure below. When set to 1 by any of

these sources, PROXCOMPSTAT will only be reset once the compensation is completed.

Figure 32 – Compensation Request Sources

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 Block startup: a compensation is automatically requested when the proximity sensing is enabled via

PROXSCANPERIOD.

 I2C: a compensation can be manually requested anytime by the host through I2C interface.

 PROXAVG update: a compensation can be automatically requested if it is detected that C

Env

has drifted

beyond a set level since the last compensation.

 PROXCOMPPRD: a compensation can be automatically requested at a predefined rate programmed by

the host.

 PROXSTUCK: a compensation can be automatically requested if it is detected that the proximity “Close”

state is lasting abnormally long.

Please note that the compensation request flag can be set anytime but the compensation itself is always done at

the beginning of a scan period to keep all parameters coherent (PROXRAW, PROXAVG, PROXDIFF), see

§ 5.3.2.

5.2.6 Analog-to-Digital Conversion (ADC)

A 12-bit ADC is used to convert the capacitance information into a digital 12-bit word PROXRAW.

The ADC is shared with the touchscreen interface using time multiplexing (see § 5.4.2 for more details).

5.3 Digital Processing

5.3.1 Overview

The main purpose of the digital processing block is to convert the raw capacitance information coming from the

AFE (PROXRAW) into a robust and reliable digital flag (PROXSTAT) indicating if the user’s finger/hand/head is

close to the proximity sensor.

The offset compensation performed in the AFE is a one time measurement. However, the environment

capacitance C

Env

may vary with time (temperature, nearby objects, etc). Hence, in order to get the best

estimation of C

User

(PROXDIFF) it is needed to dynamically track and subtract C

Env

variations. This is performed

by filtering PROXUSEFUL to extract its slow variations (PROXAVG).

PROXDIFF is then compared to user programmable threshold to extract PROXSTAT flag.

Figure 33 – Digital Processing Block Diagram

Digital processing sequencing is illustrated in figure below. At every scan period wake-up (defined by

PROXSCANPERIOD), the block updates sequentially PROXRAW, PROXUSEFUL, PROXAVG, PROXDIFF and

PROXSTAT before going back to Idle mode.

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Figure 34 – Digital Processing Sequencing

Digital processing block also updates CONVSTAT (set during proximity operations) and PROXCOMPSTAT (set

when compensation is currently pending execution or competition)

5.3.2 PROXRAW Update

PROXRAW update consists mainly in starting the AFE and waiting for the new PROXRAW value to be ready. If

a compensation was pending it is performed first.

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Figure 35 – ProxRaw Update

5.3.3 PROXUSEFUL Update

PROXUSEFUL update consists in filtering PROXRAW upfront to remove its potential high frequencies

components(system noise, interferer, etc) and extract only user activity (few Hz max) and slow environment

changes.

Figure 36 – PROXUSEFUL Update

F(PROXRAW ; PROXUSEFUL[n-1] ; PROXRAWFILT) = (1 - PROXRAWFILT).PROXRAW + PROXRAWFILT.PROXUSEFUL[n-1]

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5.3.4 PROXAVG Update

PROXAVG update consists in averaging PROXUSEFUL to ignore its “fast” variations (i.e. user finger/palm/hand)

and extract only the very slow variations of environment capacitance C

Env

One can program positive and negative debounced thresholds (PROXAVGPOSTHRESH/PROXAVGPOSDEB

and PROXAVGNEGTHRESH/PROXAVGNEGDEB) within which PROXAVG can vary without triggering

compensation (ie small acceptable environment drift).

Large positive values of PROXUSEFUL are considered as normal (user finger/hand/head) but large negative

values are considered abnormal and should be compensated quickly. For this purpose, the averaging filter

coefficient can be set independently for positive and negative variations via PROXAVGPOSFILT and

PROXAVGNEGFILT. Typically we have PROXAVGPOSFILT > PROXAVGNEGFILT to filter out (abnormal)

negative events faster.

To prevent PROXAVG to be “corrupted” by user activity (should only reflect environmental changes) it is freezes

when proximity is detected.

Figure 37 – ProxAvg vs Proximity Event

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Figure 38 – ProxAvg Update

F(PROXUSEFUL ; PROXAVG[n-1] ; PROXAVGxxxFILT) = (1 - PROXAVGxxxFILT).PROXUSEFUL + PROXAVGxxxFILT.PROXAVG[n-1]

xxx = POS or NEG

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5.3.5 PROXDIFF Update

PROXDIFF update consists in the complementary operation i.e. subtracting PROXAVG to PROXUSEFUL to

ignore slow capacitances variations (C

Env

) and extract only the user related variations i.e. C

User

Figure 39 – ProxDiff Update

5.3.6 PROXSTAT Update

PROXSTAT update consists in taking PROXDIFF information (C

User

), comparing it with a user programmable

threshold PROXTHRESH and finally updating PROXSTAT accordingly. When PROXSTAT=1, PROXAVG is

frozen to prevent the user proximity signal averaging and hence absorbed into C

Env

Figure 40 – PROXSTAT Update

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5.4 Host Operation

5.4.1 General Description

If PROXIRQSEL = 0, an interrupt can be triggered when the user is detected to be close, detected to be far, or

both (PROXCLOSEIRQEN, PROXFARIRQEN).

Figure 41 – Proximity Sensing Host Operation (Pen Trigger Mode ; RegIrqMsk[6:4] = 110 ; PROXIRQSEL = 0)

If PROXIRQSEL = 1, instead of the proximity “Far” state, an interrupt can be triggered at the end of each

proximity sensing operation indicating to the host when the proximity sensing block is running

(PROXCONVDONEIRQEN). This may be used by the host to synchronize noisy system operations or to read

PROXRAW, PROXUSEFUL, PROXAVG, PROXDIFF synchronously for monitoring purposes.

Figure 42 – Proximity Sensing Host Operation (Pen Trigger Mode ; RegIrqMsk[6:4] = 010 ; PROXIRQSEL = 1)

In both cases above, an interrupt can also be triggered at the end of compensation (PROXCOMPDONEEN).

5.4.2 Proximity Sensing vs Touch Operations

As previously mentioned, touch and proximity operations share the same ADC and hence the chip implements

time multiplexing between these two types of operations. Also, proximity sensing doesn’t need to be performed

while pen is down (not needed as host knows already something touches the screen).

In all operating modes, if PROXSCANPERIOD = 0, no proximity operation is performed (i.e. § 4.6). The following

hence assumes PROXSCANPERIOD != 0. For simplicity we also assume that NIRQ is only used for reporting

touch operations i.e. RegIrqMsk[6:4] = 000 (PROXSTAT mapped to AUX pin, or polled via I2C).

In MAN mode, a CONVERT command (if not preceded by a SELECT command) will perform a proximity

sensing operation before the touchscreen operation, whatever the pen status. Hence please note that if the

Pen Detection

NIRQ

I2C Read

RegIrqSrc

Proximity Sensing (Analog + Digital)

PROXSTAT

CONVSTAT

PROXSCANPERIOD

tick

User in range

User out of range

Pen Detection

I2C Read

RegIrqSrc

Proximity Sensing (Analog + Digital)

PROXSTAT

CONVSTAT

PROXSCANPERIOD

tick

User in range

User out of range

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touchscreen is used as the proximity sensor and is being touched when the conversion is performed, the

proximity measurement result may be incorrect.

Figure 43 – Manual Mode – CONVERT Command (CHAN = Y ; PROXSCANPERIOD != 0; Pen down)

If the screen is not touched, only the proximity sensing operation is performed.

Figure 44 – Manual Mode – CONVERT Command (CHAN = Y ; PROXSCANPERIOD != 0, Pen up)

In PENDET and PENTRG mode, a proximity sensing operation will be performed regularly as defined in

PROXSCANPERIOD, but only if pen is not detected.

Figure 45 – Pen Detect Mode (RegIrqMsk[6:2] = 00011 ; PROXSCANPERIOD = 001 ie 1/TOUCHRATE)

I2C

Channel Bias

CONVERT

Channel Conv

rsion

READ CHANNEL

PROX

NIRQ (RegIrqMsk[6:3]=0001)

CONVSTAT

Idle

Touch

Conver

sion

Pen Detection

NIRQ

Pen Touch

Pen Release

I2C Read

RegIrq

Src

Proximity Sensing

CONVSTAT

PENSTAT

TOUCHRATE

tick

I2C

Channel Bias

CONVERT

Channel Conv

rsion

READ CHANNEL

POWDLY

PROX

NIRQ (RegIrqMsk[6:3]=0001)

CONVSTAT

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Figure 46 – Pen Trigger Mode (RegIrqMsk[6:2] = 00010 ; PROXSCANPERIOD = 001 ie 1/TOUCHRATE)

5.4.3 Minimum Scan Period (i.e. PROXSCANPERIOD)

Similarly to touch operations (Cf. § 4.6.5), if PROXSCANPERIOD is too short for proximity sensing operations to

be completed, the rate tick(s) affected are ignored until operations are completed and the following tick is taken

into account for the next planned operation.

Please note that compensation lasts about ~16 times longer than a normal proximity sensing operation.

Idle

Touch

Conver

sion

Pen Detection

NIRQ

TOUCHRATE

tick

Pen Touch

Pen Release

I2C Read Channel

Proximity Sensing

PENSTAT

CONVSTAT

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6 H

APTICS

NTERFACE

(SX8654/55)

6.1 Introduction

Haptics technology is commonly used in systems which include a touchscreen interface. Its purpose is to provide

tactile feedback to the user to acknowledge a touch event hence improving greatly the robustness of the system

and user comfort and perception.

The on-chip haptics interface is designed to drive two common actuator types: Eccentric Rotating Mass (ERM)

and Linear Resonant Actuator (LRA). This is performed without any external component due to fully embedded

analog processing and with very limited host interaction due to the embedded digital processing block.

Figure 47 – Haptics Interface Overview

The host configures drive parameters from the I2C port according to the particular haptics load to be used. The

haptics drive level is then controlled in real time by either of two methods: by a dedicated digital pin, MIN, which

accepts a pulse-width-modulated (PWM) digital signal; or by writing the desired output level directly to a register

via the I2C interface.

This digital information is filtered to prevent fast transitions and hence high current spikes (HAPTBW), converted

into the analog domain by an 8-bit DAC, and finally amplified (HAPTGAIN) to provide a differential signal

between MOUTP and MOUTN pins which can be directly connected to the motor thanks to their high drive

current capability.

For better isolation from the rest of the chip, the haptics interface analog block has its own power supply pins

MVDD and MGND.

The haptics interface is enabled when HAPTTYPEEN != 0.

6.2 ERM Load

6.2.1 Introduction

An ERM is a DC motor with an off-balance load to create a vibration. Speed and direction are controlled by the

applied voltage. The ERM load is selected when HAPTTYPEEN = 10.

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Accelerating

Figure 48 – ERM Drive Signal Example

If AmplitudeCode is within HAPTSQUELCH range (for more than 512/MIN_Freq in PWM mode, for more than

512/FOSCL in I2C mode): VMOUT = 0V

Else: VMOUT(V) = (AmplitudeCode / 127) x 1.135 * HAPTGAIN

AmplitudeCode (signed) is defined differently depending on the mode selected (PWM or I2C), see below.

Please note that whatever setting, VMOUT is physically limited to [MVDD;-MVDD], i.e. saturation effect.

6.2.2 PWM Mode

PWM mode is selected when HAPTMODE = 0.

In this mode, AmplitudeCode is extracted/updated at each MIN period from MIN_DutyCycle:

•

MIN_DutyCycle ≈ 0% => AmplitudeCode = -127

•

…

•

MIN_DutyCycle = 49.6% => AmplitudeCode = -1

•

MIN_DutyCycle = 50% => AmplitudeCode = 0

•

MIN_DutyCycle = 50.4% => AmplitudeCode = +1

•

…

•

MIN_DutyCycle ≈ 100% => AmplitudeCode = +127

6.2.3 I2C Mode

I2C mode is selected when HAPTMODE = 1.

In this mode, AmplitudeCode = HAPTAMP (signed, internally sampled at FOSCL). MIN is not used and should

be grounded. HAPTRANGE must be set to 1.

6.3 LRA Load

6.3.1 Introduction

An LRA is a spring and mass with an electro-magnetic coil to move the mass. It is operated by applying an AC

signal at its resonant frequency (typ. ~175 Hz). Like pushing a swing at its resonance, it doesn’t need much

energy to keep it going, so drive current requirements are much lower than for ERMs. LRAs have moderately

high Q factors so that the drive frequency must match the resonant frequency within a few Hz to get optimum

amplitude.

LRA load is selected when HAPTTYPEEN = 01.

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Figure 49 – LRA Drive Signal Example

The carrier frequency of VMOUT_Freq is defined as following:

VMOUT_Freq(Hz) = (MIN_Freq / HAPTRANGE) (PWM mode)

VMOUT_Freq(Hz) = (MIN_Freq / HAPTRANGE) / (HAPTTIMER +1) (I2C mode)

If AmplitudeCode is within HAPTSQUELCH range (for more than 512/VMOUT_Freq):

VMOUT_Envelope = 0V

Else: VMOUT_Envelope(V) = (AmplitudeCode / 127) x 1.135 * HAPTGAIN

AmplitudeCode (signed) is defined differently depending on the mode selected (PWM or I2C), see below.

Please note that whatever setting, VMOUT is physically limited to [MVDD;-MVDD], ie saturation effect.

6.3.2 PWM Mode

PWM mode is selected when HAPTMODE = 0.

In this mode, AmplitudeCode is extracted/updated at each MIN period from MIN_DutyCycle:

•

MIN_DutyCycle ≈ 0% => AmplitudeCode = -127

•

…

•

MIN_DutyCycle = 49.6% => AmplitudeCode = -1

•

MIN_DutyCycle = 50% => AmplitudeCode = 0

•

MIN_DutyCycle = 50.4% => AmplitudeCode = +1

•

…

•

MIN_DutyCycle ≈ 100% => AmplitudeCode = +127

6.3.3 I2C Mode

I2C mode is selected when HAPTMODE = 1.

In this mode, AmplitudeCode = HAPTAMP (signed, internally sampled at MIN_Freq). MIN is still used to extract

VMOUT carrier frequency.

6.4 Short-Circuit Protection

The haptics interface integrates a short-circuit protection circuit which detects when MIDD is abnormally high i.e.

above ISHORT. Under a short-circuit event (HAPTSHORTSTAT=1) the haptics block will stop operation

(MOUTN & MOUTP grounded). When the short-circuit is removed the haptics operations will resume normally.

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7 T

EMPERATURE

ENSOR

The chip includes a temperature sensor which monitors the chip’s junction temperature. Its purpose is to provide

over-temperature information to the host and if needed automatically shutdown chip operation for thermal

protection.

Figure 50 – Temperature Sensor Overview

If TEMPALWAYSON = 0 (default), the temperature sensor will perform measurements only if the chip is active

i.e. touchscreen interface running (Op. Mode != MAN), proximity sensing interface enabled

(PROXSCANPERIOD != 0) or haptics interface enabled (HAPTTYPEEN != 00). The temperature sensor will

perform a measurement every ~32 ms (1024/FOSCL) but not during ADC conversions (temperature sensing

delayed accordingly).

If TEMPALWAYSON = 1, the temperature sensor will always perform a measurement every ~32 ms

independently from chip activity (i.e. also when the chip is inactive and during ADC conversions).

Each measurement is compared with two internally hard-coded thresholds:

 Warning level: typ. 120°C (TWRNG).

 Alarm level: typ. 155°C (TALRM)

Each of these thresholds is associated to a status flag (TEMPWARNINGSTAT, TEMPALARMSTAT) which

edges can be mapped to generate an interrupt to the host.

Additionally, during an alarm situation (i.e. temperature > alarm level) all chip operations (i.e. touchscreen,

proximity, haptics) are automatically shutdown until the temperature goes below the alarm level.

After a shutdown event all stored conversion data are thrown away. Cycling operations (TOUCHRATE > 0) will

resume from the start (i.e. if a 4 channel conversion is stopped during the 3

channel conversion, when

resuming, the 4 channels will be converted again). If the user was running some manual operation (SELECT,

CONVERT), the corresponding command will have to be re-issued. The haptics operations will resume directly.

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8 I

NTERRUPT

(NIRQ)

8.1 Introduction

The purpose of the NIRQ pin is to indicate to the host (via a falling edge) when any of the events considered

being time-critical has occurred. Non time-critical events can be monitored via I2C by reading regularly the

relevant status bits.

8.2 Registers Overview

8.2.1 RegIrqMsk

This register allows the host to decide which interrupt sources he wants to monitor via the NIRQ signal. Please

note that a reset event will always trigger NIRQ falling edge whatever RegIrqMsk (Cf § 10)

8.2.2 RegIrqSrc

This register indicates to the host which of the interrupt sources triggered the NIRQ signal. More than one bit

can be set if several events occurred before host reads the register.

If bit 3 is OFF, reading the register will clear it together with releasing NIRQ signal. Else, if bit 3 is ON and we are

in MAN or PENTRG mode, both register and NIRQ will be cleared only once all channel data have been read. All

ADC related operations (touch conversion, proximity conversion, pen detection) are stopped as long as all

channel data have not been read.

Bits which RegIrqMsk corresponding bits are set to 0 (ie source not monitored) will always read 0 even if the

event actually occurred.

8.2.3 RegStat

This register regroups all status information of the chip and is used by all interrupt sources to detect the relevant

events. For each bit, if the relevant block is ON its value is constantly updated, else it is set to 0. This register

update is completely independent from RegIrqMsk.

8.3 Host Procedure

- Configure the different blocks parameters(TS, Proximity, etc)

- Program RegIrqMsk to start monitoring what is considered to be “time-critical” events

- Enable the blocks to start RegStat update and hence NIRQ process.

- Each time NIRQ falling edge occurs, read RegIrqSrc to know which “time-critical” event occurred (+ read

channel data if relevant)

- In addition, RegStat can be read anytime to get the whole picture including also what is considered to be

“non time-critical” information.

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9 A

UXILIARY

INS

(AUX1/AUX2/AUX3)

The chip has three auxiliary pins which can be used:

1. By the touchscreen interface when using a 5-wire touchscreen (WIPER=AUX1)

2. By the proximity sensing interface (PROXSENSORCON and PROXSHIELDCON) to use an external

sensor and/or shield instead of the touchscreen’s plates

3. By the host (RegAux0-1) to monitor any RegStat and/or RegIrqSrc bits in real time without having to use

NIRQ or perform I2C polling.

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10 R

ESET

10.1 Hardware (POR and NRST)

The chip generates its own power on reset (POR) signal after a power supply is connected to the VDD pin.

NRST input pin can be used to reset the chip anytime, it must be connected to VDD (or greater) either directly (if

not used), or via a resistor.

Figure 51 – Hardware Reset Conditions

1. Device behavior is undefined until VDD rises above VPOR, at which point internal reset procedure is

started and NIRQ is kept low.

2. After t

RESET

, the reset procedure is completed and NIRQ is released high.

3. In operation, the chip may be reset at anytime by an external device driving NRST low for t

PULSE

longer. NIRQ will go low during the reset phase and chip can be accessed normally again after NIRQ

rising edge. Additionally bit RESETSTAT will be set (cleared when reading RegStat)

10.2 Software (RegReset)

Writing 0xDE to RegReset register will reset the chip and all registers to their default values. NIRQ will go low

during the reset phase and chip can be accessed normally again after NIRQ rising edge. Additionally bit

RESETSTAT will be set (cleared when reading RegStat).

10.3 ESD Event (RESETSTAT)

In case of ESD event, the chip can reset to protect its internal circuitry. NIRQ will go low during the reset phase

and chip can be accessed normally again after NIRQ rising edge. Additionally bit RESETSTAT will be set

(cleared when reading RegStat).

Undefined

RESET

Reset

Signal

VDD

VPOR

PULSE

NIRQ

Undefined

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11 I2C

NTERFACE

11.1 Introduction

The chip is a read-write slave-mode I2C device and complies with the Philips I2C standard Version 2.1 dated

January, 2000. The chip has a few user-accessible internal 8-bits registers to set the various parameters of

operation (Cf. § 12 for detailed configuration registers description). The I2C interface has been designed for

program flexibility, in that once the slave address has been sent to the chip enabling it to be a slave

transmitter/receiver, any register can be written or read independently of each other. The start and stop

commands frame the data-packet and the repeat start condition is allowed if necessary.

2 lines are used to exchange data between an external master host and the slave device:

•

SCL : Serial CLock

•

SDA : Serial DAta

Seven bit addressing is used and ten bit addressing is not allowed. Any general call address will be ignored by

the chip. The chip is not CBUS compatible and can operate in standard mode (100kbit/s) or fast mode

(400kbit/s).

11.2 I2C Address

On the QFN package an ADDR pin is made available to select between the two pre-programmed I2C addresses

of the device. On the CSP package ADDR is internally connected to ground.

This is illustrated in table below.

Package ADDR Address Description

0 0x48 (1001000) First I2C address

QFN 1 0x49 (1001001) Second I2C address

CSP 0 0x48 (1001000) First (and unique) I2C address

Table 8 – I2C Address

Please note that upon request, a custom I2C Address can be pre-programmed by Semtech.

11.3 Write Register

The I2C write register sequence is given in figure below. After the start condition [S], the chip slave address

(SA) is sent, followed by an eighth bit (W=‘0’) indicating a write. The chip then acknowledges [A] that it is being

addressed, and the host sends a CR byte consisting in ‘00’ followed by the chip register address (RA). The chip

acknowledges [A] and the host sends the appropriate data byte (WD0) to be written. Again the chip

acknowledges [A]. In case the host needs to write more data, a succeeding data byte will follow (WD1),

acknowledged by the slave [A]. This sequence will be repeated until the host terminates the transfer with the

stop condition [P].

Figure 52 – I2C Write Register

The register address increments automatically when successive data bytes (WD1...WDn) are supplied by the

host.

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The correct sampling of the screen by the chip and the host I2C bus traffic are events that might occur

simultaneously. The chip will synchronize these events by the use of clock stretching if that is required. The

stretching occurs directly after the last received command bit (see figure above).

11.4 Read Register

The I2C read register sequence is given in figure below. After the start condition [S], the chip slave address (SA)

is sent, followed by an eighth bit (W=‘0’) indicating a write. The chip then acknowledges [A] that it is being

addressed, and the host responds with a CR byte consisting in ‘01’ followed by the register address (RA). The

chip acknowledges [A] and the host sends the repeated start Condition [Sr]. Once again, the chip slave address

(SA) is sent, followed by an eighth bit (R=‘1’) indicating a read. The chip responds with an acknowledge [A] and

the data byte (RD0). If the host needs to read more data it will acknowledge [A] and the chip will send the next

data byte (RD1). This sequence will be repeated until the host terminates the transfer with a NACK [N] followed

by a stop condition [P].

Figure 53 – I2C Read Register

The register address increments automatically when successive data bytes (RD1...RDn) are read by the host.

The correct sampling of the screen by the chip and the host I2C bus traffic are events that might occur

simultaneously. The chip will synchronize these events by the use of clock stretching if that is required. The

stretching occurs directly after the last received command bit (see figure above).

11.5 Write Command (Touchscreen Interface)

The I2C write command sequence is given in figure below. After the start condition [S], the chip slave address

(SA) is sent, followed by an eighth bit (W=‘0’) indicating a write. The chip then acknowledges [A] that it is being

addressed, and the host responds with a CR byte consisting in Command(7:0) (see table below). The chip

acknowledges [A] and the host sends a stop [P].

Figure 54 – I2C Write Command

The sampling of the screen by the chip and the host I2C bus traffic are events that might occur simultaneously.

The chip will synchronize these events by the use of clock stretching if that is required. The stretching occurs

directly after the last received command bit (see figure above).

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Command Command(7:0) Function

SELECT 1 0 1 0 X Chan(2:0) Select and bias channel.

CONVERT 1 0 1 1 X Chan(2:0) Convert channel.

MAN 1 1 0 0 X X X X Enter manual mode.

PENDET 1 1 0 1 X X X X Enter pen detect mode.

PENTRG 1 1 1 0 X X X X Enter pen trigger mode.

Table 9 : Command Codes

Channel Chan(2:0) Description

X 0 0 0 X channel

Y 0 0 1 Y channel

Z1 0 1 0 First channel for pressure measurement

Z2 0 1 1 Second channel for pressure measurement

SEQ 1 1 1 Channels enabled in RegChanMsk register

Table 10 : Channel Codes

11.6 Read Channel (Touchscreen Interface)

The I2C read channel sequence is given in figure below. After the start condition [S], the chip slave address

(SA) is sent, followed by an eighth bit (R=‘1’) indicating a read. The chip responds with an acknowledge [A] and

the first data byte (RD0). The host sends an acknowledge [A] and the chip responds with the second data byte

(RD1). If the host needs to read more channels, it will acknowledge [A] and the chip will send the next data

bytes. This sequence will be repeated until the host terminates with a NACK [N] followed immediately by a stop

[P].

The channel data that can be read is defined by RegChanMsk, or the last convert command in manual mode. A

maximum number of 8 data bytes can be read when all channels (X, Y, Z1, Z2) are activated in RegChanMsk.

The STOP [P] (if following the last valid data) releases high the NIRQ line. All ADC related operations (touch

conversion, proximity conversion, pen detection) are stopped as long as all valid channel data have not been

read (ie as long as NIRQ is low).

Figure 55 – I2C Read Channel

The sampling of the screen by the chip and the host I2C bus traffic are events that might occur simultaneously.

The chip will synchronize these events by the use of clock stretching if that is required. The stretching occurs

directly after the address and read bit have been sent for the I2C read channels command (see figure above).

The channel data is sent with the following order: X, Y, Z1, Z2. It is coded as described in figure below

Typical applications require only X and Y coordinates, thus only 4 bytes of data will be read in this case.

CHAN(2:0)

RD0

D(11:8) D(7:0)

RD1

Figure 56 – Channel Data Format

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The 3 bits CHAN(2:0) are defined in the previous table and show which channel data is referenced. The channel

data D(11:0) is of unsigned format and corresponds to a value between 0 and 4095.

The chip will return 0xFFFF in case of invalid data; this occurs when:

•

host tries to read channels which have not been converted. For example if the chip converts X and Y

and the host tries to read X, Y, Z1 and Z2.

•

a conversion has been done while the screen wasn’t touched , i.e. pen up (not detected).

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12 R

EGISTERS

ETAILED

ESCRIPTION

Address Name Default Description

0x00 RegTouch0 0x00

0x01 RegTouch1 0x20

0x02 RegTouch2 0x00

0x03 RegTouch3 0x00

0x04 RegChanMsk 0xC0

Touchscreen Interface

0x05 RegHapt0 0x00

0x06 RegHapt1 0x00

0x07 RegHapt2 0x00

0x08 RegHapt3 0x80

0x09 RegHapt4 0x00

0x0A RegHapt5 0x00

Haptics Interface and Temperature Sensor

0x0B RegProx0 0x00

0x0C RegProx1 0x00

0x0D RegProx2 0x00

0x0E RegProx3 0x00

0x0F RegProx4 0x00

0x10 RegProx5 0x00

0x11 RegProx6 0x00

0x12 RegProx7 0x00

0x13 RegProx8 0x00

0x14 RegProx9 0x00

0x15 RegProx10 0x00

0x16 RegProx11 0x00

0x17 RegProx12 0x00

0x18 RegProx13 0x00

0x19 RegProx14 0x00

0x1A RegProx15 0x00

0x1B RegProx16 0x00

0x1C RegProx17 0x00

0x1D RegProx18 0x00

0x1E RegProx19 0x00

0x1F RegProx20 0x00

0x20 RegProx21 0x01

0x21 RegProx22 0x00

Proximity Sensing Interface

0x22 RegIrqMsk 0x08

0x23 RegIrqSrc 0x00

0x24 RegStat 0x00 Interrupt and Chip Status

0x25 RegAux0 0x00

0x26 RegAux1 0x00 Auxiliary Functions

0x3F RegReset 0x00 Software Reset

Table 11 : Registers Overview

NOTES:

1) Addresses not listed above are reserved and should not be written.

2) Reserved bits should be left to their default value unless otherwise specified.

3) Proximity related registers/bits do not apply to SX8655.

4) Haptics related registers/bits do not apply to SX8656.

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Bits

Variable Default

Description

7:4 TOUCHRATE 0000 Defines the touch coordinates acquisition rate:

0000 : OFF.

0001 : 10 cps

0010 : 20 cps

0011 : 40 cps

0100 : 60 cps

0101 : 80 cps

0110 : 100 cps

0111 : 200 cps

1000 : 300 cps

1001 : 400 cps

1010 : 500 cps

1011 : 1 kcps

1100 : 2 kcps

1101 : 3 kcps

1110 : 4 kcps

1111 : 5 kcps

Values above assume typical FOSCL, else vary accordingly.

3:0 POWDLY 0000 Defines the bias settling time for each channel’s first conversion:

0000 : 0.5 us

0001 : 1.1 us

0010 : 2.2 us

0011 : 4.4 us

0100 : 8.9 us

0101 : 17.8 us

0110 : 35.5 us

0111 : 71.0 us

1000 : 142 us

1001 : 284 us

1010 : 568 us

1011 : 1.14 ms

1100 : 2.27 ms

1101 : 4.55 ms

1110 : 9.09 ms

1111 : 18.19 ms

Values above assume typical FOSCH, else vary accordingly.

Table 12 : RegTouch0 (Addr 0x00)

Bits

Variable Default

Description

7:5 Reserved 001

4 TSTYPE 0 Defines the type of touchscreen:

0 : 4-wire

1 : 5-wire

3:2 RPNDT 00 Defines the pen detection circuit’s pull-up resistor value:

00 : 114 kOhms

01 : 228 kOhms

10 : 57 kOhms

11 : 28 kOhms

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1:0 FILT 00 Defines the channel filtering algorithm:

00 : OFF (Nfilt = 1)

01 : 3 sample averaging (Nfilt = 3)

10 : 5 sample averaging (Nfilt = 5)

11 : 3 sample averaging after removal of extreme values (Nfilt = 7)

Table 13 : RegTouch1 (Addr 0x01)

Bits

Variable Default

Description

7:4 Reserved 0000

3:0 SETDLY 0000 Defines the bias settling time for each channel’s subsequent conversion

(i.e. when filtering is enabled):

0000 : 0.5 us

0001 : 1.1 us

0010 : 2.2 us

0011 : 4.4 us

0100 : 8.9 us

0101 : 17.8 us

0110 : 35.5 us

0111 : 71.0 us

1000 : 142 us

1001 : 284 us

1010 : 568 us

1011 : 1.14 ms

1100 : 2.27 ms

1101 : 4.55 ms

1110 : 9.09 ms

1111 : 18.19 ms

Values above assume typical FOSCH, else vary accordingly.

Table 14 : RegTouch2 (Addr 0x02)

Bits

Variable Default

Description

7:0 Reserved 0x00

Table 15 : RegTouch3 (Addr 0x03)

Bits

Variable Default

Description

7 XCONV 1 Enables X channel conversion:

0 : OFF

1 : ON

6 YCONV 1 Enables Y channel conversion:

0 : OFF

1 : ON

5 Z1CONV 0 Enables Z1 channel conversion:

0 : OFF

1 : ON

4 Z2CONV 0 Enables Z2 channel conversion:

0 : OFF

1 : ON

3:0 Reserved 0000

Table 16 : RegChanMsk (Addr 0x04)

Bits

Variable Default

Description

7 HAPTMODE 0 Defines the haptics mode/input:

0 : PWM

1 : I2C

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6:5 HAPTTYPEEN 00 Defines the haptics load:

00 : OFF. Haptics block disabled.

01 : LRA

10 : ERM

11 : Reserved

4 HAPTRANGE 0 Defines MIN prescaler value:

0 : 128

1 : 256

3:0 HAPTGAIN 0000 Defines the haptics output gain:

0000 : 1

0001 : ~1.17

0010 : ~1.34

0011 : ~1.51

0100 : ~1.67

0101 : ~1.84

0110 : ~2.01

0111 : ~2.18

1000 : ~2.35

1001 : ~2.52

1010 : ~2.69

1011 : ~2.86

1100 : ~3.03

1101 : ~3.20

1110 : ~3.37

1111 : ~3.53

Exact formula is 1 + Code * 0.169

Table 17 : RegHapt0 (Addr 0x05)

Bits

Variable Default

Description

7:6 Reserved 00

5:3 HAPTSQUELCH 000 Defines the Haptics squelch, i.e. the range of AmplitudeCode

(HAPTAMP or MIN duty cycle equivalent, Cf. § 6) which will generate a

0V output (VMOUT):

000 : OFF. No squelch.

001 : -1 < AmplitudeCode < +1 (ie. AmplitudeCode = 0)

010 : -2 < AmplitudeCode < +2

011 : -4 < AmplitudeCode < +4

100 : -8 < AmplitudeCode < +8

101 : -16 < AmplitudeCode < +16

110 : -32 < AmplitudeCode < +32

111 : -64 < AmplitudeCode < +64

2 TEMPWRNIRQEDG 0 Enables TempWrnIrq to be generated when the chip temperature gets

below the alarm threshold :

0 : OFF. TempWrnIrq generated only when the chip temperature gets

above the alarm threshold.

1 : ON. TempWrnIrq generated both when the chip temperature gets

above and below the alarm threshold.

1 TEMPALRMIRQEDG 0 Enables TempAlrmIrq to be generated when the chip temperature gets

below the alarm threshold :

0 : OFF. TempAlrmIrq generated only when the chip temperature gets

above the alarm threshold.

1 : ON. TempAlrmIrq generated both when the chip temperature gets

above and below the alarm threshold.

0 TEMPALWAYSON 0 Enables the temperature monitoring even when no operation (touch,

proximity, haptics) is enabled:

0 : OFF

1 : ON

Table 18 : RegHapt1 (Addr 0x06)

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Bits

Variable Default

Description

7:0 HAPTAMP 0x00 Defines the haptics output polarity and level in I2C mode i.e.

AmplitudeCode (Cf. § 6) :

0xFF : +127 (Max positive)

…

0x81 : +1

0x80 : +0

0x00 : -0

0x01 : -1

…

0x7F : -127 (Max negative)

HAPTAMP[7] gives the sign of AmplitudeCode (1=>+;0=>-) while

HAPTAMP[6:0] give its magnitude.

Table 19 : RegHapt2 (Addr 0x07)

Bits

Variable Default

Description

7:5 HAPTBW 100 Defines the haptics low-pass filter cut off frequency (Hz):

000 : OFF. No filtering.

001 : ~210 * SamplingFreq / 100

010 : ~280 * SamplingFreq / 100

011 : ~425 * SamplingFreq / 100

100 : ~565 * SamplingFreq / 100

101 : ~700 * SamplingFreq / 100

110 : ~850 * SamplingFreq / 100

111 : ~980 * SamplingFreq / 100

SamplingFreq is VMOUT_Freq in LRA mode and MIN_Freq (PWM) or

FOSCL (I2C) in ERM mode (Cf. § 6)

4 HAPTHZ 0 Sets MOUTP and MOUTN to high impedance (HZ):

0 : Normal

1 : HZ

3 HAPTSHORTPROT 0 Disables short-circuit protection:

0 : ON . A short-circuit event will automatically stop haptics operation.

1 : OFF. A short-circuit event will not stop haptics operation.

In both cases HAPTSHORTSTAT is still updated (and hence an

interrupt can still be generated if needed)

2:0 HAPTTIMERMSB 000 Defines the haptics timer overflow value used to generate the LRA’s

128 or 256 multiple frequency from MIN.

Table 20 : RegHapt3 (Addr 0x08)

Bits

Variable Default

Description

7:0 HAPTTIMERLSB 0x00 Defines the haptics timer overflow value used to generate the LRA’s

128 or 256 multiple frequency from MIN.

HAPTTIMER[9:0] values below 8 (ie 0-7) are reserved.

Table 21 : RegHapt4 (Addr 0x09)

Bits

Variable Default

Description

7:0 Reserved 0x00

Table 22 : RegHapt5 (Addr 0x0A)

Bits

Variable Default

Description

7 PROXRAWFILTSEL 0 Defines the proximity raw filtering range for PROXRAWFILT :

0 : Fast

1 : Slow

6 PROXIRQSEL 0 Defines the function of bits 5 of RegIrqMsk and RegIrqSrc.

0 : ProxFar

1 : ProxConvDone

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5:4 PROXHYST 00 Defines the proximity detection hysteresis :

00 : OFF

01 : 32

10 : 128

11 : 512

3:0 PROXSCANPERIOD 0000 Defines the proximity scan period :

0000 : OFF. Proximity sensing disabled

0001 : 1 / TOUCHRATE (Cf. RegTouch0)

0010 : 2 / TOUCHRATE

0011 : 4 / TOUCHRATE

0100 : 8 / TOUCHRATE

0101 : 16 / TOUCHRATE

0110 : 32 / TOUCHRATE

0111 : 64 / TOUCHRATE

1000 : 128 / TOUCHRATE

1001 : 256 / TOUCHRATE

1010 : 512 / TOUCHRATE

1011 : 1024 / TOUCHRATE

1100 : 2048 / TOUCHRATE

1101 : 4096 / TOUCHRATE

1110 : 8192 / TOUCHRATE

1111 : 16384 / TOUCHRATE

Table 23 : RegProx0 (Addr 0x0B)

Bits

Variable Default

Description

7:0 PROXTHRESH 0x00 Defines the proximity detection threshold (for PROXSTAT update).

Threshold = 16 x register value

Table 24 : RegProx1 (Addr 0x0C)

Bits

Variable Default

Description

7:6 PROXCLOSEDEB 00 Defines the “Close” debounce (for PROXSTAT update):

00 : OFF

01 : 2 samples

10 : 4 samples

11 : 8 samples

5:4 PROXFARDEB 00 Defines the “Far” debounce (for PROXSTAT update):

00 : OFF

01 : 2 samples

10 : 4 samples

11 : 8 samples

3:0 PROXCOMPPRD 0000 Defines the periodic compensation :

0 : OFF

Else : register value x 128 samples

Table 25 : RegProx2 (Addr 0x0D)

Bits

Variable Default

Description

7:0 PROXSTUCK 0x00 Defines the stuck at timeout (ie max “Close” time before a

compensation is automatically requested) :

0 : OFF

Else : register value x 16 samples

Table 26 : RegProx3 (Addr 0x0E)

Bits

Variable Default

Description

7:0 PROXAVGPOSTHRESH

0x00 Defines the average positive threshold (for compensation).

Threshold = 8 x register value

Table 27 : RegProx4 (Addr 0x0F)

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Bits

Variable Default

Description

7:5 PROXAVGPOSDEB 000 Defines the average positive debounce (for compensation) :

000 : OFF

001 : 2 samples

010 : 4 samples

011 : 8 samples

100 : 16 samples

101 : 32 samples

110 : 64 samples

111 : 128 samples

4:2 PROXAVGPOSFILT 000 Defines the average positive filter coefficient :

000 : 0 (ie filtering OFF)

001 : 1 – 1/2

010 : 1 – 1/4

011 : 1 – 1/8

100 : 1 – 1/16

101 : 1 – 1/32

110 : 1 – 1/64

111 : 1 – 1/128

1:0 PROXRAWFILT 00 Defines the raw filter coefficient.

If PROXRAWFILTSEL = 0 :

00 : 0 (ie filtering OFF)

01 : 1 – 1/2

10 : 1 – 1/4

11 : 1 – 1/8

If PROXRAWFILTSEL = 1 :

00 : 1 – 1/16

01 : 1 – 1/32

10 : 1 – 1/64

11 : 1 – 1/128

Table 28 : RegProx5 (Addr 0x10)

Bits

Variable Default

Description

7:0 PROXAVGNEGTHRESH

0x00 Defines the average negative threshold (for compensation).

Threshold = – 8 x register value

Table 29 : RegProx6 (Addr 0x11)

Bits

Variable Default

Description

7:5 PROXAVGNEGDEB 000 Defines the average negative debounce (for compensation) :

000 : OFF

001 : 2 samples

010 : 4 samples

011 : 8 samples

100 : 16 samples

101 : 32 samples

110 : 64 samples

111 : 128 samples

4:2 PROXAVGNEGFILT 000 Defines the average negative filter coefficient :

000 : 0 (i.e. filtering OFF)

001 : 1 – 1/2

010 : 1 – 1/4

011 : 1 – 1/8

100 : 1 – 1/16

101 : 1 – 1/32

110 : 1 – 1/64

111 : 1 – 1/128

1 PROXHIGHIM 0 Enables high noise immunity mode :

0 : OFF

1 : ON, at the expense of higher power consumption.

0 Reserved 0

Table 30 : RegProx7 (Addr 0x12)

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Bits

Variable Default

Description

7:4 Reserved 0000

3:0 PROXRAWMSB 0000 Provides the proximity raw information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 31 : RegProx8 (Addr 0x13)

Bits

Variable Default

Description

7:0 PROXRAWLSB 0x00 Provides the proximity raw information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 32 : RegProx9 (Addr 0x14)

Bits

Variable Default

Description

7:4 Reserved 0000

3:0 PROXUSEFULMSB 0000 Provides the proximity information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 33 : RegProx10 (Addr 0x15)

Bits

Variable Default

Description

7:0 PROXUSEFULLSB 0x00 Provides the proximity information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 34 : RegProx11 (Addr 0x16)

Bits

Variable Default

Description

7:4 Reserved 0000

3:0 PROXAVGMSB 0000 Provides the proximity average information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 35 : RegProx12 (Addr 0x17)

Bits

Variable Default

Description

7:0 PROXAVGLSB 0x00 Provides the proximity average information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 36 : RegProx13 (Addr 0x18)

Bits

Variable Default

Description

7:5 Reserved 0000

4:0 PROXDIFFMSB 0000 Provides the proximity differential information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 37 : RegProx14 (Addr 0x19)

Bits

Variable Default

Description

7:0 PROXDIFFLSB 0x00 Provides the proximity differential information for monitoring purposes.

Signed, 2's complement format.

Read-only (using PROXCONVDONE), do not write.

Table 38 : RegProx15 (Addr 0x1A)

Bits

Variable Default

Description

7:0 PROXOFFSETMSB 0x00 Provides the proximity compensation offset information for monitoring

purposes. Read-only (using PROXCONVDONE), do not write.

Table 39 : RegProx16 (Addr 0x1B)

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Bits

Variable Default

Description

7:0 PROXOFFSETLSB 0x00 Provides the proximity compensation offset information for monitoring

purposes. Read-only (using PROXCONVDONE), do not write.

Table 40 : RegProx17 (Addr 0x1C)

Bits

Variable Default

Description

7 Reserved 0

6:4 PROXSENSITIVITY 000 Defines the sensitivity :

000 : 0 (Min)

001 : 1

010 : 2

011 : 3

100 : 4

101 : 5

110 : 6

111 : 7 (Max)

3:1 PROXFREQ 000 Defines the operating frequency :

010 : 64 kHz

011 : 90 kHz

100 : 112 kHz

101 : 150 kHz (recommended)

Else : Reserved

0 Reserved 0

Table 41 : RegProx18 (Addr 0x1D)

Bits

Variable Default

Description

7:4 PROXSENSORCON 0000 Defines the proximity sensor connection, Cf. § 5.1 :

0000 : None

0001 : AUX1/WIPER (5-wire TS)

0010 : AUX2 (external)

1000 : X (standard 4-wire TS)

1001 : Y (inverted 4-wire TS)

Else : Reserved

3:0 PROXSHIELDCON 0000 Defines the proximity shield connection, Cf. § 5.1 :

0000 : None

0011 : AUX3 (external)

1000 : X (inverted 4-wire TS)

1001 : Y (standard 4-wire TS or 5-wire TS)

Else : Reserved

Table 42 : RegProx19 (Addr 0x1E)

Bits

Variable Default

Description

7:6 Reserved 00

5:3 PROXBOOST 000 Enables proximity boost mode (higher sensitivity) :

100 : ON

110 : OFF (recommended; compulsory when sensor is TS)

Else : Reserved

2:0 Reserved 000 Must be set to 100.

Table 43 : RegProx20 (Addr 0x1F)

Bits

Variable Default

Description

7:0 Reserved 0x01 Must be set to 0x81.

Table 44 : RegProx21 (Addr 0x20)

Bits

Variable Default

Description

7:0 Reserved 0x00

Table 45 : RegProx22 (Addr 0x21)

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Bits

Variable Default

Description

7 HAPTSHORTIRQEN 0 Enables the HaptShort interrupt.

0 : OFF

1 : ON

6 PROXCLOSEIRQEN 0 Enables the ProxClose interrupt.

0 : OFF

1 : ON

5 PROXFARIRQEN/

PROXCONVDONEIRQEN 0 Enables the ProxFar/ProxConvDone interrupt. Cf RegProx0[6]

0 : OFF

1 : ON

4 PROXCOMPDONEIRQEN 0 Enables the ProxCompDone interrupt.

0 : OFF

1 : ON

3 PENTOUCHIRQEN/

TOUCHCONVDONEIRQEN

1 Enables the PenTouch/TouchConvDone interrupt

0 : OFF

1 : ON

2 PENRELEASEIRQEN 0 Enables the PenRelease interrupt.

0 : OFF

1 : ON

1 TEMPWARNINGIRQEN 0 Enables the TempWarning interrupt.

0 : OFF

1 : ON

0 TEMPALARMIRQEN 0 Enables the TempAlarm interrupt.

0 : OFF

1 : ON

Table 46 : RegIrqMsk (Addr 0x22)

Bits

Variable Default

Description

7 HAPTSHORTIRQ 0 Gives the HaptShort interrupt source status. (ie

HAPTSHORTSTAT rising edge)

6 PROXCLOSEIRQ 0 Gives the ProxClose interrupt source status. (ie PROXSTAT

rising edge)

5 PROXFARIRQ/

PROXCONVDONEIRQ 0 Gives the ProxFar (ie PROXSTAT falling edge), or

ProxConvDone (ie CONVSTAT falling edge after proximity

conversion) interrupt status depending on PROXIRQSEL .

4 PROXCOMPDONEIRQ 0 Gives the ProxCompDone interrupt source status. (ie

PROXCOMPSTAT falling edge)

3 PENTOUCHIRQ/

TOUCHCONVDONEIRQ 0 Gives the PenTouch/TouchConvDone interrupt source status. (ie

in PENDET mode -> PENSTAT rising edge, else -> CONVSTAT

falling edge after touch conversion)

2 PENRELEASEIRQ 0 Gives the PenRelease interrupt source status. (ie PENSTAT

falling edge)

1 TEMPWARNINGIRQ 0 Gives the TempWarning interrupt source status. (ie

TEMPWARNINGSTAT rising/falling edge depending on

TEMPWRNIRQEDG)

0 TEMPALARMIRQ 0 Gives the TempAlarm interrupt source status. (ie

TEMPALARMSTAT rising/falling edge depending on

TEMPALRMIRQEDG)

Table 47 : RegIrqSrc (Addr 0x23)

Bits

Variable Default

Description

7 HAPTSHORTSTAT 0 Gives the haptics short-circuit instantaneous status :

0 : No short circuit is currently present

1 : A short circuit is currently present

6 RESETSTAT 0 Gives the reset latched status :

0 : No reset occurred

1 : A reset occurred

This bit is cleared when RegStat is read.

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5 PROXSTAT

0 Gives the proximity instantaneous status:

0 : Far (or proximity sensing disabled)

1 : Close

PROXSTAT (and PROXAVG) is automatically frozen to its

current value if pen is down (whether TS or AUXi is the sensor)

PROXSTAT is NOT frozen while haptics is running, if needed

host can turn proximity sensing ON/OFF via

PROXSCANPERIOD.

4 PROXCOMPSTAT

0 When read, this bit indicates gives the compensation

instantaneous status :

0 : No compensation is currently pending

1 : A compensation is currently pending execution and/or

completion

When set to ‘1’, triggers a compensation for next scan period.

3 CONVSTAT

0 Gives touch/proximity conversion instantaneous status :

0 : No touch or proximity conversion is currently running

1 : A touch or proximity conversion is currently running

2 PENSTAT

0 Gives the pen instantaneous status :

0 : Released/Up

1 : Touching/Down

1 TEMPWARNINGSTAT

0 Gives the temperature warning instantaneous status :

0 : Temperature is below warning threshold

1 : Temperature is above warning threshold

0 TEMPALARMSTAT

0 Gives the temperature alarm instantaneous status :

0 : Temperature is below alarm threshold

1 : Temperature is above alarm threshold

Table 48 : RegStat (Addr 0x24)

Bits

Variable Default

Description

7 Reserved 0

6 AUX1DIGOUTEN 0 Enables the digital output capability of AUX1

0 : OFF

1 : ON, Cf. AUX1DIGOUT.

Bit is ignored if TSTYPE = 1 or PROXSENSORCON = 0001

5 AUX2DIGOUTEN 0 Enables the digital output capability of AUX2

0 : OFF

1 : ON, Cf. AUX2DIGOUT.

Bit is ignored if PROXSENSORCON = 0010

4 AUX3DIGOUTEN 0 Enables the digital output capability of AUX3

0 : OFF

1 : ON, Cf. AUX3DIGOUT.

Bit is ignored if TSTYPE = 1 or PROXSHIELDCON = 0011

3:0 AUX1DIGOUT 0000 Defines the digital signal to output on AUX1 :

0000 : RegIrqSrc(0) 1000 : RegStat(0)

0001 : RegIrqSrc(1) 1001 : RegStat(1)

0010 : RegIrqSrc(2) 1010 : RegStat(2)

0011 : RegIrqSrc(3) 1011 : RegStat(3)

0100 : RegIrqSrc(4) 1100 : RegStat(4)

0101 : RegIrqSrc(5) 1101 : RegStat(5)

0110 : RegIrqSrc(6) 1110 : RegStat(6)

0111 : RegIrqSrc(7) 1111 : RegStat(7)

Table 49 : RegAux0 (Addr 0x25)

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Bits

Variable Default

Description

7:4 AUX2DIGOUT 0000 Defines the digital signal to output on AUX2 :

0000 : RegIrqSrc(0) 1000 : RegStat(0)

0001 : RegIrqSrc(1) 1001 : RegStat(1)

0010 : RegIrqSrc(2) 1010 : RegStat(2)

0011 : RegIrqSrc(3) 1011 : RegStat(3)

0100 : RegIrqSrc(4) 1100 : RegStat(4)

0101 : RegIrqSrc(5) 1101 : RegStat(5)

0110 : RegIrqSrc(6) 1110 : RegStat(6)

0111 : RegIrqSrc(7) 1111 : RegStat(7)

3:0 AUX3DIGOUT 0000 Defines the digital signal to output on AUX3 :

0000 : RegIrqSrc(0) 1000 : RegStat(0)

0001 : RegIrqSrc(1) 1001 : RegStat(1)

0010 : RegIrqSrc(2) 1010 : RegStat(2)

0011 : RegIrqSrc(3) 1011 : RegStat(3)

0100 : RegIrqSrc(4) 1100 : RegStat(4)

0101 : RegIrqSrc(5) 1101 : RegStat(5)

0110 : RegIrqSrc(6) 1110 : RegStat(6)

0111 : RegIrqSrc(7) 1111 : RegStat(7)

Table 50 : RegAux1 (Addr 0x26)

Bits

Variable Default

Description

7:0 SOFTRESET 0x00 Writing 0xDE will reset the chip and all registers to their default

values.

Table 51 : RegReset (Addr 0x3F)

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

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SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

13 A

PPLICATION

NFORMATION

13.1 Typical Application Circuit

Figure 57 – Typical Application Circuit

13.2 External Components Recommended Values

Symbol Description Note Min Typ. Max Unit

CVDD Main supply decoupling capacitor - 1 - uF

CMVDD

Motor supply decoupling capacitor - 10 - uF

CVREG

Regulator decoupling capacitor +/- 20%, ESR<1Ω - 100 - nF

RPULL Host interface pull-ups +/- 50% - 10 - kΩ

CTB Proximity sensor-to-shield

capacitance - - <0.7 1.5 nF

RXY Proximity sensor serial resistor - - <1 1.5 kΩ

RMOT Motor resistance - 7.5 - - Ω

CMOUT

Motor output capacitor - - 1 - uF

Table 52 : External Components Recommended Values

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

July 2011 60 www.semtech.com

SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

14 P

ACKAGING

NFORMATION

14.1 QFN Package

Figure 58 - Outline Drawing - QFN

Figure 59 - Land Pattern - QFN

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

July 2011 61 www.semtech.com

SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

14.2 CSP Package

Figure 60 - Outline Drawing - CSP

Figure 61 - Land Pattern - CSP

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

July 2011 62 www.semtech.com

SX8654/SX8655/SX8656

Haptics Enabled 4/5-

Wire

Resistive Touchscreen Controller with Proximity Sensing

Contact Information

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