Revision V1.0/October 2010
©2010 Semtech Corp.
SX8653
www.semtech.com
Page 1
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
-----4
The SX8653 is a touch controller for 4 or 5 wire resistive
touchscreen. With 4-wire touchscreen, the multitouch
feature enables a completely different user interaction. It
enables detection of 2 fingers on the touchscreen and
several gestures like rotation and pinch/ stretch.
It features a wide input supply range from 1.65V to 3.7V and
low power modes to preserve current when the screen is
unintentionally touched.
To compute touch screen X-Y coordinates and touch
pressure with precision, a low power 12-bit analog-digital
converter is activated with the possibility to enable on-chip
data averaging processing algorithms to reduce host activity
and suppress system noise.
The touch screen controller inputs have been specially
designed to provide robust on-chip ESD protection of up to
±15kV in both HBM and Contact Discharge, and eliminates
the need for external protection devices. The SX8653 is
controlled by a high speed SPI™ serial interface.
The SX8653 is available in a 4.0 mm x 3.0 mm 14-DFN
package and a 1.5 mm x 2.0 mm wafer level chip scale
package (WLCSP) for space conscience applications.
DSC, DVR, Cell Phones
PDA, Pagers
Point-of-Sales Terminals
Touch-Screen Monitors
Extremely Low Power Consumption: 23uA@1.8V 8kSPS
Support Multi-touch operation (4-wire)
Superior On-chip ESD Protection
±15kV HBM (X+,X-,Y+,Y-)
±2kV CDM
±25kV Air Gap Discharge
±15kV Contact Discharge
±300V MM
Pin-compatible with SX8652
Single 1.65V to 3.7V Supply/Reference
4-Wire or 5-Wire Resistive Touch Screen Interface
Integrated Preprocessing Block to Reduce Host Loading
and Bus Activity
Four User Programmable Operation Modes provides
Flexibility to address Different Application Needs
Manual, Automatic, Pen Detect, Pen Trigger
Precision, Low Noise, High Speed 12-bit SAR ADC
Operating At 74k SPS
Throughput: 5000 (X-Y) coordinates/second (c/s) with 7-
Sample Averaging
Low Power Shut-Down Mode < 1uA
SPI™ Serial Interface
Touch Pressure Measurement (4-Wire)
Auxiliary Input (4-Wire) For Alternate ADC Input or Start
of Conversion Trigger
Hardware & Software reset
-40°C to +85°C operation
Pb-Free, Halogen Free, RoHS/WEEE compliant product
Windows CE 6.0, Linux Driver Support Available
Packages: 14-LD (4.0 mm x 3.0 mm) DFN
12-Ball (1.5 mm x 2.0 mm) WLCSP
GENERAL DESCRIPTION
APPLICATIONS
ORDERING INFORMATION
Part Number Package
(Dimension in mm)
Marking
SX8653ICSTRT
1
1. 3000 Units / reel
12 - Ball WLCSP
(1.5x2.0)
NB2A
SX8653IWLTRT
1
14 - Lead DFN
(4.0x 3.0)
NB2A
KEY PRODUCT FEATURES
Touch
Screen
Interface
SX8653
VDD
X+/BR
Y+/TR
X-/TL
Y-/BL DIN
NIRQ
SCLK
DOUT
GND
Control
SPI
Digital
Filter
ref+
ref- ADCin out
OSC
POR
Vref
NCS
AUX/WIPER
VDD
To the
Host
To the
touch
screen
NRST (DFN only)
Revision V1.0/October 2010
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SX8653
www.semtech.com
Page 2
Section Page
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Table of contents
1. General Description................................................................................................................................................. 4
1.1. DFN Pinout Diagram and Marking Information (Top View).............................................................................. 4
1.2. WLCSP Pinout Diagram and Marking Information (Top View) ........................................................................ 4
1.3. Pin Description................................................................................................................................................. 5
1.4. Simplified Block Diagram................................................................................................................................. 5
2. Electrical Characteristics ......................................................................................................................................... 6
2.1. Absolute Maximum Ratings ............................................................................................................................. 6
2.2. Recommended Operating Conditions.............................................................................................................. 6
2.3. Thermal Characteristics................................................................................................................................... 6
2.4. Electrical Specifications................................................................................................................................... 7
2.5. Host Interface Specifications ........................................................................................................................... 9
2.6. Host Interface Timing Waveforms.................................................................................................................... 9
3. Functional Description........................................................................................................................................... 10
3.1. General Introduction ..................................................................................................................................... 10
3.2. Device Interface and ESD protection............................................................................................................. 11
3.2.1. Touchscreen interface............................................................................................................................. 11
3.2.2. Host Interface and Control Pins .............................................................................................................. 11
4. 4-wire Touch Screen Detailed Description ............................................................................................................ 12
4.1. Touch Screen Operation................................................................................................................................ 12
4.2. Coordinates Measurement............................................................................................................................. 12
4.3. Pressure Measurement.................................................................................................................................. 13
4.4. Pen Detection ................................................................................................................................................ 13
4.5. Double touch measurement........................................................................................................................... 14
5. 5-wire Touch Screen Detailed Description ............................................................................................................ 15
5.1. Touch Screen Operation................................................................................................................................ 15
5.2. Coordinates Measurement............................................................................................................................. 15
5.3. Pen Detection ................................................................................................................................................ 15
6. Data Processing .................................................................................................................................................... 16
7. Power-Up, Reset ................................................................................................................................................... 16
8. Modes of Operation............................................................................................................................................... 16
8.1. MANual Mode ................................................................................................................................................ 17
8.2. AUTOmatic mode .......................................................................................................................................... 17
8.3. PENDET Mode .............................................................................................................................................. 18
8.4. PENTRIG Mode............................................................................................................................................. 18
9. Host Interface ........................................................................................................................................................ 20
9.1. SPI Read/Write Registers.............................................................................................................................. 20
9.2. SPI Reading Channel Data............................................................................................................................ 20
9.3. SPI implementation and multiple Read/Write ................................................................................................ 21
9.4. Invalid Qualified Data..................................................................................................................................... 22
Revision V1.0/October 2010
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SX8653
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Section Page
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Table of contents
9.5. Register Map................................................................................................................................................. 23
9.6. SX8653 register ............................................................................................................................................ 24
10. Application Information......................................................................................................................................... 25
10.1. Acquisition Setup........................................................................................................................................... 25
10.2. Channel Selection.......................................................................................................................................... 25
10.3. Noise Reduction............................................................................................................................................. 25
10.3.1. POWDLY................................................................................................................................................. 25
10.3.2. SETDLY .................................................................................................................................................. 26
10.4. AUX Input - 4-wire touchscreen only ............................................................................................................. 26
10.5. Interrupt Generation....................................................................................................................................... 26
10.6. Coordinate Throughput Rate ......................................................................................................................... 26
10.6.1. SPI Communication Time ....................................................................................................................... 26
10.6.2. Conversion Time..................................................................................................................................... 27
10.7. ESD event...................................................................................................................................................... 27
11. Multi-Touch Gestures with 4-wire touchscreen...................................................................................................... 28
11.1. Zoom Gesture................................................................................................................................................ 28
11.2. Rotate Gesture............................................................................................................................................... 28
12. Packaging Information........................................................................................................................................... 29
12.1. DFN Package................................................................................................................................................. 29
12.2. WLCSP Package........................................................................................................................................... 30
Revision V1.0/October 2010
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ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
1. General Description
1.1. DFN Pinout Diagram and Marking Information (Top View)
Figure 1. SX8653 DFN Top View, Pad on Bottom Side
YYWW: date code
XXXXX: Lot Number
1.2. WLCSP Pinout Diagram and Marking Information (Top View)
Figure 2. SX8653 WLCSP Top View, Solder Bumps on Bottom Side
YYWW: date code
XXXXX: Lot Number
1
2
3
4
5
6
14
13
12
11
10
9
AUX/
WIPER (NC)
VDD
X+/BR
Y+/TR
X-/TL
NRST
DIN
NCS
NIRQ
DOUT
Y-/BL
15
7
GND 8SCLK
PIN 1
IDENTIFIER
NB2A
YYWW
XXXXX
#
A
NIRQ SCLKDOUT
B C D
3
2
1
VDD NCS GNDDIN
X+/BR Y+/TR Y-/BLX-/TL
AUX/WIPER
NB2A
YYWW
XXXXXX
BALL A1 IDENTIFIER
Revision V1.0/October 2010
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ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
1.3. Pin Description
Table 1. Pin description
1.4. Simplified Block Diagram
The SX8653 simplified block diagram is shown in Figure 3.
Figure 3. Simplified block diagram of the SX8653
Pin Number
#Name Type Description
DFN WLCSP
1 A1 AUX/WIPER Digital Input /
Analog Input Conversion Synchronization (4-wire) or
Analog Auxiliary Input (4-wire) / Wiper Input (5-wire)
2 A2 VDD Power Input Input power supply, connect to a 0.1uF capacitor to GND
3 A3 X+/BR Analog IO X+ Right electrode (4-wire) / Bottom Right (5-wire) channel
4 B3 Y+/TR Analog IO Y+ Top electrode (4-wire) /Top Right (5-wire) channel
5 C3 X-/TL Analog IO X- Left electrode (4-wire) /Top Left (5-wire) channel
6 D3 Y-/BL Analog IO Y- Bottom electrode (4-wire) /Bottom Left (5-wire) channel
7 D2 GND Ground Ground
8 D1 SCLK Digital Input SPI Serial Clock Input
9 C2 DIN Digital Output SPI Serial Data Input
10 C1 DOUT Digital Output SPI Serial Data Output
11 B1 NIRQ Digital Output, open drain Interrupt Request Output, Active low, Need external pull-up
12 B2 NCS Digital Input SPI Chip Select Input, Active low
13 - NRST Digital Input DFN package only, Reset Input, Active low, Internal pull-up resistor
14 - (NC) Not Connected
15 - GND Power input Backside Ground
Touch
Screen
Interface
SX8653
VDD
X+/BR
Y+/TR
X-/TL
Y-/BL DIN
NIRQ
SCLK
DOUT
GND
Control
SPI
Digital
Filter
ref+
ref- ADCin out
OSC
POR
Vref
NCS
AUX/WIPER
VDD
To the
Host
To the
touch
screen
NRST (DFN only)
Revision V1.0/October 2010
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ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
2. Electrical Characteristics
2.1. Absolute Maximum Ratings
Stresses above the values listed in “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the device at these, or any other conditions beyond the “Recommended Operating
Conditions”, is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability
.
(i) Tested to TLP (10A)
(ii) Tested to JEDEC standard JESD22-A114
(iii) Tested to JEDEC standard JESD78
2.2. Recommended Operating Conditions
2.3. Thermal Characteristics
(
iii) θ
JA
is calculated from a package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under exposed pad (if applicable)
per JESD51 standards.
Parameter Symbol Min. Max. Unit
Supply Voltage V
DDABS
-0.5 3.9 V
Input voltage (non-supply pins) V
IN
-0.5 3.9 V
Input current (non-supply pins) I
IN
10 mA
Operating Junction Temperature T
JCT
125 °C
Reflow temperature T
RE
260 °C
Storage temperature T
STOR
-50 150 °C
ESD HBM
(Human Body Model)
High ESD pins: X+/BR, X-/TL,
Y+/TR, Y-/BL, Aux/Wiper ESD
HBM1
± 15
(i)
kV
± 8
(ii)
kV
All pins except high ESD pins ESD
HBM2
± 2 kV
ESD (Contact Discharge) High ESD pins: X+/BR, X-/TL,
Y+/TR, Y-/BL, Aux/Wiper ESD
CD
± 15 kV
Latchup
(iii)
I
LU
± 100 mA
Table 2. Absolute Maximum Ratings
Parameter
Symbol Min. Max Unit
Supply Voltage V
DD
1.65V 3.7 V
Ambient Temperature Range T
A
-40 85 °C
Table 3. Recommended Operating Conditions
Parameter
Symbol Min. Max Unit
Thermal Resistance with DFN package - Junction to Ambient
(iii)
θ
JA
39 °C/W
Thermal Resistance with WLCSP package - Junction to Ambient
(iii)
θ
JA
65 °C/W
Table 4. Thermal Characteristics
Revision V1.0/October 2010
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ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
2.4. Electrical Specifications
All values are valid within the recommended operating conditions unless otherwise specified.
Parameter
Symbol Conditions Min. Typ Max Unit
Current consumption
Mode = MANUAL I
pwd
Converter stopped, pen
detection off, SPI listening,
OSC stopped
0.4 1 uA
Mode = PENDET I
pndt
Converter stopped, pen
detection activated, device
generates interrupt upon
detection, SPI listening, OSC
stopped
0.4 1 uA
Mode =PENTRIG I
pntr
Converter stopped, pen
detection activated, device
starts conversion upon pen
detection. SPI listening, OSC
stopped
0.4 1 uA
Mode=AUTO I
auto
Converter stopped, pen
detection off, SPI listening,
OSC on, timer on
1.5 uA
Operation @8kSPS, VDD=1.8V I
opl
23 50 uA
Operation @42kSPS, VDD=3.3V I
oph
105 140 uA
Digital I/O
High-level input voltage V
IH
0.8V
DD
V
DD
+0.2 V
Low-level input voltage V
IL
V
SS
-0.3 0.2V
DD
V
Hysteresis V
HysLow
VDD > 2V 0.05 V
DD
V
V
HysHigh
VDD < 2V 0.1 V
DD
V
Output Logic High V
OH
I
OH
>-2mA 0.8V
DD
Output Logic Low V
OL
I
OL
<2mA 0 0.4 V
Input leakage current L
I
CMOS input ±1 uA
High ESD Input - Output
capacitance C
X+/BR
,C
X-/TL
,C
Y+/TR
, C
Y-/BL,
C
AUX
50 pF
Input - Output capacitance C
NRST ,
C
NIRQ
,C
NCS
,C
DIN
,
C
DOUT,
C
SCLK
5 pF
Table 5. Electrical Specifications
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DATASHEET
Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
Startup
Power-up time t
por
Time between rising edge VDD
and rising NIRQ 1 ms
ADC
Resolution A
res
12 bits
Offset A
off
±1 LSB
Gain error A
ge
At full scale 0.5 LSB
Differential Non Linearity A
dnl
±1 LSB
Integral Non Linearity A
inl
±1.5 LSB
Resistors
X+, X-, Y+, Y- resistance R
chn
Touch Pad Biasing Resistance 5 Ohm
Pen detect resistance R
PNDT_00
R
PNDT
= 0 100 kOhm
R
PNDT_01
R
PNDT
= 1 200 kOhm
R
PNDT_10
R
PNDT
= 2 50 kOhm
R
PNDT_11
R
PNDT
= 3 25 kOhm
External components recommendations
Capacitor between VDD, GND C
vdd
Type 0402, tolerance +/-50% 0.1 uF
Parameter
Symbol Conditions Min. Typ Max Unit
Table 5. Electrical Specifications
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Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
2.5. Host Interface Specifications
(i) All timing specifications refer to voltage levels (50% VDD, V
OH
, V
OL
) defined in Table 6 unless otherwise mentioned.
Table 6. Host Interface Specifications
2.6. Host Interface Timing Waveforms
Figure 4. SPI Timing Waveform
Parameter Symbol Condition Min Typ Max Unit
SPI TIMING SPECIFICATIONS
(i)
SCLK
Clock Frequency
Duty Cycle f
SCLK
duty 40 5000
60 kHz
%
NCS edge to first SCLK “↑” T
CSS
50
ns
NCS edge to DOUT Low T
DCD
100
SCLK High Pulse Width T
CKH
80
SCLK Low Pulse Width T
CKL
80
Data Setup Time T
DS
40
Data Valid to SCLK Hold Time T
DH
70
Data Output Delay after SCLK “↓” T
DOD
70
NCS “↑” to SCLK Ignored T
CSI
50
NCS “↑” to DOUT Hi-Z state T
CCZ
90
NCS Hold Time T
CSW
150
tCKH
tDS tDH
tCSS tCKL
tDCD
tDOD
tCSW
tCSI
tCCZ
CSN
SCLK
DIN
DOUT D11 VOL
VOH
50%VDD
50%VDD
50%VDD
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Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
3. Functional Description
3.1. General Introduction
This section provides an overview of the SX8653 architecture, device pinout and a typical application.
The SX8653 is designed for 4-wire and 5-wire resistive touch screen applications. The touch screen or touch panel is the
resistive sensor and can be activated by either a finger or stylus. When the top layer is pressed, it makes contact with the
bottom sheet and the touch location can be measured.
As shown in Figure 5 with a 4-wire panel, the touch screen coordinates and touch pressure are converted into SPI format
by the SX8653 for transfer to the host.
The auxiliary input can be used to convert with 12-bit resolution any analog input in the supply range. It can also serves as
an external synchronisation input to trig the touchscreen acquisition as described in the Application Information section.
Figure 5. SX8653 with a 4-wire touch screen
A 5-wire touchscreen application is shown in Figure 6. The 5-wire top sheet acts as a voltage measuring probe. The
measurement accuracy is not affected by damage on this sheet and consequently the reliability is improved.
Multitouch and touch pressure measurement are not possible with 5-wire touchscreen.
Figure 6. SX8653 with a 5-wire touch screen
Touch
Screen
Interface
SX8653
VDD
X+/BR
Y+/TR
X-/TL
Y-/BL
DIN
NIRQ
SCLK
DOUT
GND
Control
SPI
Digital
Filter
ref+
ref- ADCin out
OSC
POR
Vref
NCS
AUX/WIPER
VDD
NRST (DFN only)
HOST
INT
DIO
CS
SCLK
MISO
MOSI
SPI
Interface
4-wire touchscreen
Touch
Screen
Interface
SX8653
VDD
X+/BR
Y+/TR
X-/TL
Y-/BL DIN
NIRQ
SCLK
DOUT
GND
Control
SPI
Digital
Filter
ref+
ref- ADCin out
OSC
POR
Vref
NCS
AUX/WIPER
VDD
NRST (DFN only)
HOST
INT
DIO
CS
SCLK
MISO
MOSI
SPI
Interface
5-wire touchscreen
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Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
3.2. Device Interface and ESD protection
The touch screen controller inputs have been specially designed to provide robust on-chip ESD protection of up to ±15kV
in both HBM and Contact Discharge.
3.2.1. Touchscreen interface
The X+/BR, X-/TL, Y+/TR,Y-/BL, AUX/WIPER are the pins dedicated for the touchscreen interface. It provides the voltage
sequence in order to obtain the coordinates and pressure measurement.
The five pins are connected to BR, TL, TR, BL, WIPER on a 5-wire touchscreen. They are the electrodes on the 4 corners
of the bottom layer of the touchscreen plus the electrode on the top layer.
On a 4-wire touchscreen, only 4 electrodes are used: X+,X-,Y+,Y-. The AUX pin is not needed and therefore can be used
to convert an analog signal (range GND - VDD) into 12-bit digital value. The touchscreen interface pins are the most
exposed pins for an ESD event.
As shown in Figure 7, theses pins have internal ESD protection to GROUND and VDD.
3.2.2. Host Interface and Control Pins
The SX8653 is a slave device configured via the SPI interface. DIN and SCLK have internal ESD protection to GROUND
and VDD.
NIRQ provides an interrupt to the host processor when a pen is detected or when channel data is available. The NIRQ pin
is an active low, open drain output to facilitate interfacing to different supply voltages and thus requires an external pull-up
resistor (1-10 kOhm).
The host can reset the chip via the SPI interface or with the dedicated pin NRST. The NRST pin is an active low input with
an internal pull-up that provides a hardware reset.
NRST and NIRQ pins are protected to GROUND.
Figure 7. ESD protection
T o u c h
S cre e n
D rive rs
Inte rfa ce
R
c h n
A
D
C
C o n tro l
D a ta P ro cessin g
X + /B R
X -/T L
Y + /T R
Y -/B L
A U X /
W ip e r
M U X
R
c h n
R
c h n
R
c h n
P o w e r
Management
V D D
G N D
N R S T
N IR Q
SPI
NCS
SCLK
DOUT
DIN
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Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
4. 4-wire Touch Screen Detailed Description
4.1. Touch Screen Operation
A 4-wire resistive touch screen consists of two resistive sheets separated by an insulator (Figure 4.2).
Figure 8. 4-wire Touch Screen
When a pressure is applied on the top sheet with a stylus for example, a connection with the lower sheet is made.
The contact point split the Rxtot bottom resistance in the vertical axis into two resistances
R1 and R2. In the same way, the Rytot resistance in the horizontal axis of the top sheet is
divided into two resistances R3 and R4.
The touchscreen controller imposes a voltage level on X or Y electrodes allowing the
detection of the contact position.
4.2. Coordinates Measurement
During the touch, the top and bottom touchscreen layers
are connected. The resistance between the two sheets
is R
T
. A current coming from the reference voltage goes
from X+ to X- to perform the X coordinate
measurement. Figure 9 shows the measurement
schematics.
Since the ADC had a high input impedance, no current
flows through R
T
and R3. The positive ADC input is
biased with a voltage created by the R1, R2 voltage
divider.
The conversion with the 12 bit ADC gives the X location.
Figure 9. Abscissa (X) coordinates measurement
The Y coordinate is measured in a similar fashion with the measurement setup given in Table 7.
X-
Y+
Y- X+
Top conductive sheet
Bottom conductive sheet
Y electrodes
X electrodes
Y-
Y+
Rytot
Top conductive sheet before
the stylus contact
Y-
Y+
R4
R3
Top conductive sheet after
the stylus contact
Contact point
with the top
conductive
sheet
Rxtot R1R2+=
Rytot R3R4+=
X-
X+
R2
R1
+
-
R
T
Y-
Y+
R4
R3
Xpos
+
-ADC
Vref
Xpos 4095 R2
R1R2+
--------------------
⋅=
Ypos 4095 R4
R3R4+
--------------------
⋅=
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Multitouch 15kV ESD protection 4-Wire / 5-Wire
Resistive Touchscreen Controller with SPI Interface
4.3. Pressure Measurement
The 4-wire touchscreen allows pressure measurement. The contact resistance between the two sheets are a function of
the pressure applied on the top sheet. Indeed, the a low pressure applied with the finger will create a small contact area.
With a greater pressure, the contact area will be bigger and the R
T
resistance smaller.
The R
T
contact resistance is therefore an indication of the applied pressure. R
T
is deducted from Z1 and Z2 measurement.
The measurement setup given in Table 7 allows to find Z1 and Z2.
Arranging Z1 and Z2 with Rxtot and Rytot allows the
computation of R
T
.
An alternative calculation method is using Xpos and Ypos.
Table 7. Measurement setup
4.4. Pen Detection
The pen detection circuitry is used to detect a user action on the
touchscreen. The contact between the two layers generates an interrupt or
starts an acquisition sequence.
Doing a pen detection prior to conversion avoids feeding the host with
dummy data and saves power.
If the touchscreen is powered between X+ and Y- through a resistor R
PNDT
,
no current will flow so long as pressure is not applied to the surface (see
Figure 10).
When a pressure is applied, a current path is created and brings X+ to the
level defined by the resistive divider determined by R
PNDT
and the sum of
R1, R
T
and R4.
Figure 10. 4-wire pen detection circuitry
R
PNDT
should be set to the greatest value of 200 kOhm for optimal detection (see Table 16). Increasing PowDly settings
can also improve the detection on panel with high resistance.
The pen detection will set the PENIRQ bit of the RegStat register. The PENIRQ bit will be cleared and the NIRQ will be de-
asserted as soon as the host reads the status register.
In PENDET mode, the pen detection will set NIRQ low.
Measurement Vref + Vref- ADC +
XX+ X- Y+
YY+ Y- X+
Z1 X+ Y- Y+
Z2 X+ Y- X-
z1 4095 R4
R1R4R
T
+ +
---------------------------------
⋅=z2 4095 R4Rt+
R1R4R
T
+ +
---------------------------------
⋅=
R
T
Rytot Ypos
4095
------------ z2
z1
----- 1–⋅ ⋅=
R
T
Rytot Y⋅pos
4095
------------------------------- 4095
z1
------------ 1– Rxtot 1Xpos
4095
-------------
–⋅–⋅=
X-
X+
R2
R1
Vref
+
-R
T
Y-
Y+
R4
R3
R
PNDT
Sb
Rb IRQ
Q
Q
Internal
logic
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4.5. Double touch measurement
The simplified model for double touch on the touchscreen is given in Figure 11.
Two fingers on the touchscreen create two contacts between the touchscreen top
and bottom layer. The two contacts have the resistance Rt1 and Rt2.
The two contact points split Rxtot and Rytot on the horizontal and vertical axis. Then
we have R1, R2 and R3 on the top plate and R4, R5 and R6 on the bottom plate.
The determination of theses resistances is a complex task.
The SX8653 allows to measure Rx and Ry which is a combination of theses
resistances. With a S/W running in the host, it is possible to detect the gesture
described in the section Multi-Touch Gestures with 4-wire touchscreen.
Figure 11. Touchscreen model for double touch
To get the best gesture detection, the resistor RmSelX and RmSelY should be set according to the panel resistance and
the Table 8.
Table 8. RmSelX and RmSelY resistance selection
Y Panel resistance (Ohm)
RmSelY
X Panel resistance (Ohm)
RmSelX
100 to 187 000 100 to 187 000
188 to 312 001 188 to 312 001
313 to 938 010 313 to 938 010
939 to 1875 011 939 to 1875 011
1876 to 4375 100 1876 to 4375 100
4376 to 9375 101 4376 to 9375 101
9376 to 18780 110 9376 to 18780 110
Larger than 18780 111 Larger than 18780 111
R1
R2
R3
R4
R5
R6
X+ Y+
X- Y-
Rt1
Rt2
Rxtot R1R2R3+ +=
Rytot R4R5R6+ +=
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5. 5-wire Touch Screen Detailed Description
5.1. Touch Screen Operation
As the 4-wire, the 5-wire resistive touch screen consists of two resistive
sheets separated by an insulator (Figure 12). The main difference is that
the 4 wires are connected on the 4 corners of the bottom conductive
sheet. They are referred as Top Left, Top Right, Bottom Left, Bottom
Right.
The fifth wire is embedded in the top sheet and is used for sensing the
electrode voltage and is referred as the wiper.
Figure 12. 5-wire touchscreen
5.2. Coordinates Measurement
When the electrodes TL is connected with BL and TR with BR, they form with the linearization pattern 2 electrodes bars
which are very similar to the X electrodes in a 4-wire touchscreen. In the same way, the association of TL with TR and BL
with BR create Y electrodes.
The four corners are therefore able to produce voltage gradients in the horizontal and vertical axis. The wiper is connected
to the high input impedance of the ADC. When a pressure is applied on the top sheet, the contact point split the bottom
sheet resistance into R1 and R2 on the X axis and R3 and R4 on the Y axis.
The X and Y position converted by the 12-bit ADC
gives the following result.
5.3. Pen Detection
The BR pin is connected to the positive pin of the reference voltage through
R
PNDT
. The wiper panel is grounded at the AUX/WIPER pin to provide the
grounding path for a screen touch event.
The BR pin is monitored to detect voltage drop. When a pressure is applied on
the top surface, a current path is created between the two layers and the
PENIRQ bit of the RegStat register will be set. R
PNDT
should be set to the
greatest value of 200 kOhm for optimal detection (see Table 16). Increasing
PowDly settings can also improve the detection on panel with high resistance.
In PENDET mode, the pen detection will set NIRQ low.
Figure 13. 5-wire pen detection circuitry
TL
BL
Bottom conductive sheet
TR
BR
Top conductive sheet
Wiper
Linearisation
pattern
Xpos 4095 R2
R1R2+
--------------------
⋅=Ypos 4095 R4
R3R4+
--------------------
⋅=
BR
R1
Vref
+
-
AUX/
WIPER -
RPNDT
Sb
Rb
Q
Q
Internal
logic
Bottom
layer
Top
layer
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6. Data Processing
The SX8653 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 N
filt
as seen in Table 9.
The sn samples from the ADC can be averaged. The processed cn 12-bit value is then send through the SPI bus.
The noise rejection will be improved with a high order to the detriment of the power consumption.
The K coefficient in Table 9 is a filter constant. Its value is K=4079/4095.
Table 9. Filter order
7. Power-Up, Reset
During power-up, NIRQ pin is kept low, the POR reset all
registers and states of the SX8653. The SX8653 is not
accessible and SPI communications are ignored.
As soon as NIRQ rises, the SX8653 is in manual mode with
only the SPI peripheral enabled to minimize power
consumption.
The host can reset the SX8653 by setting the NRST pin low or
via the SPI bus. Writing the code 0xDE to the register
RegSoftReset reset the circuit.
When NRST is driven LOW by the host, NIRQ will be driven low
by the SX8653. After the reset NIRQ will be released by the
SX8653.
Figure 14. Power-up, NIRQ
8. Modes of Operation
The SX8653 has four operation modes that are configured using the SPI commands as defined in Table 14 and Table 16.
These 4 modes are:
manual (command ‘MANAUTO’ and RATE=0),
automatic (command ‘MANAUTO’ and RATE>0),
pen detect (command ‘PENDET’),
pen trigger mode (command ‘PENTRG’).
FILT N
filt
Explanation Processing
0 1 No average
1 3 3 ADC samples are averaged
2 5 5 ADC samples are averaged
3 7 7 ADC samples are sorted and
the 3 center samples are
averaged
sncn
=
sn1
3
---
K
cncn1– cn2–
+ +( )=
sn1
5
---
K
cncn1– cn2– cn3– cn4–
+ + + +( )=
cmax1cmax2cacbcccmin1cmin2
≥ ≥ ≥ ≥ ≥ ≥
sn1
3
---
K
cacbcc
+ +( )=
voltage
time
voltage
time
VDD
NIRQ
t
POR
VDD/2
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In the PENDET mode the pen detection is activated. The SX8653 will generate an interrupt (NIRQ) upon pen detection and
set the PENIRQ bit in the SPI status register. To quit the PENDET mode the host needs to configure the manual mode.
In the PENTRG mode the pen detection is activated and a channel conversion will start after the detection of a pen. The
SX8653 will generate an interrupt (NIRQ) upon pen detection and set the CONVIRQ bit in the SPI status register. To quit
the PENTRIG mode the host needs to configure the manual mode. The PENTRG mode offers the best compromise
between power consumption and coordinate throughput.
8.1. MANual Mode
In manual mode (RATE=0), the host sequences all the actions by the SPI commands described in Table 10.
When a command is received, the SX8653 executes the associated task and waits for the next command.
Table 10. CONVERT and SELECT command
The channel can be biased for an arbitrary amount of time by first sending a SELECT command and then a CONVERT
command once the settling time requirement is met.
The SELECT command can be omitted if the large range of POWDLY settings cover the requirements. In the latter case,
the CONVERT command alone is enough to perform an acquisition.
With CHAN=SEQ, multiple channels are sampled. This requires programming the POWDLY field in register RegCTRL0.
The selected channel will be powered during POWDLY before a conversion is started. The channel bias is automatically
removed after the conversion has completed.
8.2. AUTOmatic mode
In automatic mode (RATE > 0), SX8653 start the acquisition when a touch is detected. It converts all the channels selected
with RegChnMsk and set NIRQ low when it is finished.
After the host has read the channels, if CONDIRQ=1 and the touch is detected again, the SX8653 starts a new conversion
cycle.
To not loose data, the SX8653 does not begin conversion before the host read all the channels.
We can define the time ts between the start of the conversion and the end of the channels reading by the host.
The rate programmed is achieved if ts<1/RATE otherwise the new rate is 1/ts.
When the control CONDIRQ bit (see register RegStat Table 16) is set to ‘1’ then the interrupts will only be generated if the
pen detect occurred. This result in a regular interrupt stream, as long as the host performs the read channel commands,
and the screen is touched. When the screen is not touched, interrupts does not occur.
If the control CONDIRQ bit is cleared to ‘0’, the interrupts will be always generated. In case there is no pen detected on the
screen then the coordinate data will be qualified as invalid, see section [9.5]. This result in a regular interrupt stream as
long as the host performs the read channel commands,
This working is illustrated in Figure 17.
Figure 15 shows the SPI working in automatic mode with CONDIRQ=1. After the first sentence send through the SPI to
make the initialization, traffic is reduced as only reads are required.
Command
Action
CONVERT(CHAN)
Select and bias a channel
Wait for the programmed settling time (POWDLY)
Start conversion
SELECT(CHAN)
Select and bias a channel
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The processing time is the
necessary time for the SX8653 to
makes the pen detection, the
settling time (POWDLY) and the
conversion of the selected
channels. This time increases with
the number of channel selected
and the filter used. NIRQ interrupt
signal notifies the host when the
conversions are done.
The host just need to read the
channels data to release the
interrupt.
Figure 15. SPI working in AUTO mode
8.3. PENDET Mode
The PENDET mode can be used if the host only needs to know if the screen has been touched or not and take from that
information further actions. When pen detect circuitry is triggered the interrupt signal NIRQ will be generated and the status
register bit ‘PENIRQ’ will be set. The bit is cleared by reading the status register RegStat. The PENDET working is
illustrated in Figure 17.
8.4. PENTRIG Mode
The PENTRIG mode offers the best
compromise between power consumption
and coordinate throughput.
In this mode the SX8653 will wait until a pen
is detected on the screen and then starts the
coordinate conversions. The host will be
signaled only when the screen is touched and
coordinates are available. The flowchart is
describes in Figure 17.
The coordinate rate in pen trigger mode is
determined by the speed of the host reading
the channels and the conversion times of the
channels. The host performs the minimum
number of SPI commands in this mode.
The host has to wait for the NIRQ interrupt to
make the acquisition of the data.
The SPI working is illustrated in Figure 16.
Figure 16. SPI working in PENTRIG mode
CS
DIN
DOUT
TOUCH
NIRQ
Read Channel Data CMD
Data from SX8652 Processing time
Time is 1/RATE
CS
DIN
DOUT
TOUCH
NIRQ
Read Channel Data CMD
Data from SX8652
Conversion time
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Figure 17. AUTO, PENDET and PENTRIG Mode Flowchart
Touch Detected ?
Start channel conversion
Set interrupt
NIRQ=0
Release Interrupt
NIRQ=1
All channel
data read
All conversion
finished
yes
no
PENTRIG MODE
CONDIRQ=1 ?
Touch Detected ?
Set timer=RATE
Start timer
Start channel conversion
Set interrupt
NIRQ=0
Release Interrupt
NIRQ=1
yes
Timer expire
All channel
data read
All conversion
finished
yes
no
AUTO MODE
Touch Detected ?
Set interrupt
NIRQ=0
Release Interrupt
NIRQ=1
RegStat read
yes
no
PENDET MODE
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9. Host Interface
The host interfaced is composed of a SPI bus. It performs the read/ write operations on the registers and channels data.
9.1. SPI Read/Write Registers
The WRITE command allows the host to write a single or multiple registers in the SX8653. The host can read single or
multiple registers from the SX8653 by the READ command. This is defined in Table 11.
9.2. SPI Reading Channel Data
Five channels can be sampled by the SX8653: X, Y, Z1, Z2 and AUX. They are defined in Table 13. They can be converted
in sequence with the RegChanMsk register.
The READCHAN command allows the host to read the data obtained after the channels conversion and processing.
Table 12. Read Channels Data
The channel data are 12-bit of unsigned format which corresponds to integers between 0 and 4095. This is send on two
bytes, MSB first then LSB. A mask with the value 0x0FFF (4095) must be done to filter the four first unknown bit.
When a channel data has been transmitted, the next one is sent in the successive order: X,Y, Z1, Z2 and AUX. If a channel
has not been converted, the data is not transmitted.
When the channel data buffer gets empty, the data will carry an invalid data as explained in the channel data format.
Remark: After a conversion sequence, it is possible to read only one time the same channel.
Example: the SX8653 is set to convert X and Y. The value 0xC0 is set in RegChanMsk. The first byte read after the
READCHAN command will be X(MSB), then X(LSB), Y(MSB) and at the end Y(LSB). If the host carry on the reading, it will
get invalid data.
W/R command name CR(7:0) Function
7 6 5 4 3 2 1 0
WRITE(RA) 0 0 0 RA(4:0) Write register (see Table 15 for RA)
READ(RA) 0 1 0 RA(4:0) Read register (see Table 15 for RA)
Table 11. W/R commands
W/R command name CR(7:0) Function
7 6 5 4 3 2 1 0
READCHAN 0 0 1 x x x x x Read data from channel
Channel CHAN(2:0) Function
210
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
AUX 1 0 0 Auxiliary channel
RX 1 0 1 Double touch RX measurement
RY 1 1 0 Double touch RY measurement
SEQ 1 1 1 Channel sequentially selected from RegChanMsk register, (see Table 16)
Table 13. Channel definition
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9.3. SPI Host Commands
.The host can issue commands to change the operation mode or perform manual actions as defined in Table 14.
9.4. SPI implementation and multiple Read/Write
The SPI implemented on the SX8653 is set to the common setting CPOL=0 and CPHA=0 which means data are sampled
on the rising edge of the clock, and shifted on the falling one.
The default state of the clock when NCS gets asserted is low. If a host send a command while the system is busy, the
command is discarded.
The SPI protocol is designed to be able to do multiple read/write during a transaction. During one single operation, as long
as NCS stay asserted, the register address is automatically increased to allow sequential read/write (or sequential retrieval
of data). Between each different operation though (READ/WRITE/READCHAN), the communication should be restarted.
This is described in Figure 18.
command name CR(7:0) Function
7 6 5 4 3 2 1 0
SELECT(CHAN) 1 0 0 0 x CHAN(2:0) Bias channel (see Table 13 for CHAN)
CONVERT(CHAN) 1 0 0 1 x CHAN(2:0) Bias channel (see Table 13 for CHAN)
MANAUTO 1 0 1 1 x x x x Enter manual or automatic mode.
PENDET 1 1 0 0 x x x x Enter pen detect mode.
PENTRG 1 1 1 0 x x x x Enter pen trigger mode.
Table 14. Host Commands
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Figure 18. Data channel format
9.5. Invalid Qualified Data
The SX8653 returns 0xFFFF data in case of invalid qualified data.
This occurs:
When the SX8653 has read all the channel data in the FIFO
When a conversion is done without a pen being detected.
NCS
SCLK
DIN
DOUT
1110 9 8 7 6 5 4 3 2 1 0
001
1110 9 8 7 6 5 4 3 2 1 0
Reading Channel Data
NCS
SCLK
DIN
DOUT
7 6 5 4 3 2 1 0
0 1 0
RA[4:0]
Reading Register
7 6 5 4 3 2 1 0
NCS
SCLK
DIN
DOUT
0 0 0
RA[4:0]
Writing Register
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Multiple WriteSingle Write
Multiple ReadSingle Read
Multiple ReadSingle Read
NCS
SCLK
DIN
DOUT
Other command
CMD
Unknown bit
Multiple access
Single access
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9.6. Register Map
The details of the registers are described in the next sections.
Register Address RA(4:0)
Register Description
0 0000 RegCtrl0 Write, Read
0 0001 RegCtrl1 Write, Read
0 0010 RegCtrl2 Write, Read
0 0011 RegCtrl3 Write, Read
0 0100 RegChanMsk Write, Read
0 0101 RegStat Read
1 1111 RegSoftReset Write
Table 15. Register address
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9.7. SX8653 register
Register Bit Default Description
RegCtrl0
7:4 0000 RATE
Set rate in coordinates per sec (cps) (± 20%)
If RATE =0: Manual mode. if RATE >0: Automatic mode
0000: Timer disabled -Manual mode
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: 1k cps
1100: 2k cps
1101: 3k cps
1110: 4k cps
1111: 5k cps
3:0 0000 POWDLY
Conversion (or first conversion when filtering is enabled) settling time (± 10%)
0000: Immediate (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: 0.14 ms
1001: 0.28 ms
1010: 0.57 ms
1011: 1.14 ms
1100: 2.27 ms
1101: 4.55 ms
1110: 9.09 ms
1111: 18.19 ms
RegCtrl1
7:6 00 AUXAQC
00: AUX is used as an analog input (4-
wire only)
01: On rising AUX edge, wait POWDLY
and start acquisition
10: On falling AUX edge, wait POWDLY
and start acquisition
11: On rising and falling AUX edges,
wait POWDLY and start acquisition
The AUX trigger works only in manual mode with 4-wire touchscreen
5 1 CONDIRQ
Enable conditional interrupts
0: interrupt always generated at end of
conversion cycle. If no pen is detected
the data is set to ‘invalid qualified’.
1: interrupt generated when pen detect
is successful
4 0 SCREEN Select the type of screen:
0: 4-wire 1: 5 -wire
3:2 00
RPDNT
Select the Pen Detect Resistor
00: 100 kOhm
01: 200 kOhm 10: 50 kOhm
11: 25 kOhm
1:0 00 FILT Digital filter control
00: Disable
01: 3 sample averaging
10: 5 sample averaging
11: 7 sample acquisition, sort, average 3
middle samples
RegCtrl2
7:4 0 don’t care
3:0 0000 SETDLY
Settling time while filtering (± 10%)
0000: Immediate (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: 0.14 ms
1001: 0.28 ms
1010: 0.57 ms
1011: 1.14 ms
1100: 2.27 ms
1101: 4.55 ms
1110: 9.09 ms
1111: 18.19 ms
Table 16. SX8653 Register
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10. Application Information
This section describes in more detail application oriented data.
10.1. Acquisition Setup
Prior to an acquisition, the SX8653 can be setup by writing the control registers. Registers are written by issuing the
register write command. They can be read by issuing the read command. Please refer to the section [9.7].
10.2. Channel Selection
The SX8653 can be setup to start a single channel conversion or to convert several channels in sequence. For a single
conversion, the channel to be converted is determined from the CHAN(2:0) field in the command word (defined in
Table 13).
Several channels defined in RegChanMsk can be acquired sequentially by setting the CHAN(2:0) field to SEQ. The
channels will be sampled in the order X, Y, Z1, Z2, AUX.
10.3. Noise Reduction
A noisy environment can decrease the performance of the controller. For example, an LCD display located just under the
touch screen can adds a lot of noise on the high impedance A/D converter inputs.
10.3.1. POWDLY
RegCtrl3
7:6 0 don’t care
5:3 RmSelY Check Table 8
2:0 RmSelX Check Table 8
RegChanMsk
7 1 XCONV 0: no sample 1: Sample X channel
6 1 YCONV 0: no sample 1: Sample Y channel
5 0 Z1CONV 0: no sample 1: Sample Z1 channel
4 0 Z2CONV 0: no sample 1: Sample Z2 channel
3 0 AUXCONV 0: no sample 1: Sample AUX channel
0 0 RXCONV 0: no sample 1: Sample RX channel
0 0 RYCONV 0: no sample 1: Sample RY channel
0 0 don’t care
RegStat
Host writing to this register is ignored.
7 0 CONVIRQ 0: no IRQ pending
1: Conversion sequence finished
IRQ is cleared by the channel data read command
6 0 PENIRQ Operational in pen detect mode
0: no IRQ pending
1: Pen detected IRQ pending
IRQ is cleared by the RegStat reading
5 1 RSTEVENT A reset event has occurred
4:0 00000 don’t care
RegSoftReset
7:0 0x00 Writing 0xDE to this register reset the SX8653
Any other data will not affect the SX8653
Register Bit Default Description
Table 16. SX8653 Register
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In order to perform correct coordinates acquisition properly, some time must be given for the touch screen to reach a
proper level. It is a function of the PCB trace resistance connecting the SX8653 to the touchscreen and also the
capacitance of the touchscreen. We can define tau as the RC time constant. POWDLY duration should be programmed to
10 tau to reach 12 bit accuracy.
Adding a capacitor from the touch screen drivers to ground is a solution to minimize external noise but it increases settling
time and consequently the power consumption.
10.3.2. SETDLY
A best method to filter noise is described in section [6] (Data processing). When filtering is enabled, the channel will be
biased initially during a time of POWDLY for the first conversion. The parameter SETDLY sets the settling time between the
subsequent conversions in a filter set. In most applications, SETDLY can be set to 0. In applications with a high tau and
where accuracy of 1LSB is required SETDLY should be increased.
10.4. AUX Input - 4-wire touchscreen only
The AUX input can be used to sample an analog signal in the range 0-VDD. For system supply by battery, the battery
voltage can be monitored for example. The conversion is done in sequence with the touchscreen acquisition therefore the
sample rate is defined with RegCtrl0 in AUTO mode.
The AUX pin can also triggered conversions. A rising edge, a falling edge or both applied on the AUX pin can trigger the
conversion. This is defined by AUXACQ in RegCtrl1.
This method can be used to sample touchscreen when there is noise-free periods.
10.5. Interrupt Generation
An interrupt (NIRQ=0) will be generated:
During the power-up phase or after a reset
After completion of a conversion in MANUAL, PENTRIG or AUTO mode. CONVIRQ (bit [7] of RegStat) will be set at the
same time.
After a touch on the panel being detected in PENDET mode. PENIRQ (bit [6] of RegStat) will be set at the same time.
The NIRQ will be released and pulled high(NIRQ=1) by the external pull-up resistor:
When the power-up phase is finished
When the host read all channels data that were previously converted by the SX8653 in MANUAL, PENTRIG or AUTO
mode. CONVIRQ will be cleared at the same time.
When the host read the status register in PENDET mode. PENIRQ, will be cleared at the same time.
An active NIRQ (low) needs to be cleared before any new conversions will occur.
10.6. Coordinate Throughput Rate
The coordinate throughput rate depends on the following factors:
The SPI communication time: T
com
The conversion time: T
conv
The coordinate rate is the frequency to get the X, Y, Z1 and Z2 coordinate:
10.6.1. SPI Communication Time
The minimum time to read the channel data in PENTRIG mode is:
The highest throughput will be obtained with a SPI frequency of 5MHz when the host read the channel data as quickly as
possible after the NIRQ falling edge.
CoordRate 1
T
com
T
conv
+
-------------------------------
=
T
com
8 16 N
chan
×+( ) T
SPI
×=
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10.6.2. Conversion Time
The maximum possible throughput can be estimated with the following equation
with:
N
filt
= {1,3,5,7} based on the order defined for the filter FILT (see Figure 9).
N
chan
= {1,2,3,4,5,6,7} based on the number of channels defined in RegChanMsk
POWDLY = 0.5us to 18.19ms, settling time as defined in RegCtrl0
SETDLY = 0.5us to 18.19ms, settling time when filtering as defined in RegCtrl2
Tosc is the oscillator period (555ns +/- 15%)
Table 17 gives some examples of Coordinate Rate and Sample Rate for various setting in PENTRIG mode.
10.7. ESD event
In case of ESD event, the chip may reset to protect its internal circuitry. The bit
RSTEVENT
indicates that a reset event has
occurs.ESD event may trig the pen detection circuitry. In this case wrong data will be send to the host. To detect this false
coordinates on 4-wire touchscreen, Z1 and Z2 can be read. The conditions Z1<LowThreshold and Z2>HighThreshold may
indicate an ESD event. The values LowThreshold and HighThreshold are given for indication only on the table below and
should be fine tune according to the system.
Table 18. Threshold to detect false coordinates
Nch
[1..5 ] Nfilt
[1 3 5 7] PowDly
[uS] SetDly
[uS] Tconv
[uS] Tcomm
[uS] CoordRate
[kSPS]
21 0.5 -
51 8 16.7
23 71 0.5
190 8 5.0
43 140 0.5
740 14 1.3
Table 17. Coordinate throughput examples
LowThreshold HighThreshold
10 4070
T
conv
47 T
osc
⋅N+
chan
POWDLY SETDLY N
filt
1–( ) T
osc
21N
filt
1+( )+ +[ ]=
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11. Multi-Touch Gestures with 4-wire touchscreen
11.1. Zoom Gesture
A simple thumb and forefinger “pinch” movement that enables a
user to enlarge objects onscreen (moving fingers away from each
other) or make them smaller (move them towards each other).
This intuitive zooming function replaces the standard point-and-
click functionality of a mouse and provides far greater accuracy to
the user.
Figure 19. Zoom gesture
11.2. Rotate Gesture
Rotate objects onscreen by making simple clockwise (right) or
counterclockwise (left) movements with the anchored thumb and
forefinger. This multi-touch function enables swift and accurate
positioning of objects without needing to point and click repeatedly on
a rotate left-right function button in order to achieve the desired effect.
Figure 20. Rotate gesture
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12. Packaging Information
12.1. DFN Package
Figure 21. DFN Package Outline Drawing
Figure 22. DFN Package Land Pattern
MILLIMETERS
0.50 BSC
0.00A1
E1
aaa
bbb
N
e
L
A2
D1
D
E
b
1.55
0.30
3.90
2.90
3.05
-
0.18
DIM
A
DIMENSIONS
0.70
MIN
0.02 0.05
3.10
4.10
1.80
3.30
0.50
0.30
1.70
0.40
0.10
0.08
14
3.00
(0.20)
3.20
4.00
0.25 -
0.80
MAX
-
NOM
AB
PIN1
INDICATOR
(LASER MARK)
aaa C
C
SEATING
PLANE
1 2
N
bbb C A B
COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
NOTES:
2.
1.
D
E
A1
e
bxN
D1
D/2
E/2
E1
LxN
A
A2
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
3.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
NOTES:
2.
DIM
X
Y
H
K
P
C
G
MILLIMETERS
(2.90)
0.30
0.70
1.70
0.50
3.30
2.20
DIMENSIONS
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
3.60
Z
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12.2. WLCSP Package
Figure 23. WLCSP Package Outline Drawing
Figure 24. WLCSP Land Pattern of WLCSP
0.10 C
0.08 C
0.05 C A B
CONTROLLING DIMENSIONS ARE IN MILLIMETERS
NOTES:
1.
AB
C
A
B
C
INDEX AREA
A1 CORNER
0.25±0.02 SEATING
1 2 3
D
1.5±0.10
2.0±0.10
0.50
1.00
0.25
0.50
1.50
12X Ø0.315±0.03
PLANE
0.625 Max.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
NOTES:
2.
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS
0.50
0.25 1.50
0.50
1.00
12X Ø0.25
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