SX8652ICSTRT Semtech, SX8652ICSTRT Datasheet - Page 10

• Manufacturer Part Number: SX8652ICSTRT
• Description: 4/5-wire Resistive Touch Screen Controller (SPI)
• Manufacturer: Semtech

3. Functional Description
3.1. General Introduction
This section provides an overview of the SX8652 architecture, device pinout and a typical application.
The SX8652 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 SX8652 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.
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 but the touch
pressure can not be calculated.
Revision V1.7/October 2010
©2010 Semtech Corp.
ADVANCED COMMUNICATIONS & SENSING
4-wire touchscreen
5-wire touchscreen
Figure 5. SX8652 with a 4-wire touch screen
Figure 6. SX8652 with a 5-wire touch screen
AUX/WIPER
X-/TL
Y+/TR
Y-/BL
X+/BR
VDD
AUX/WIPER
X+/BR
Y+/TR
X-/TL
Y-/BL
Interface
VDD
Screen
Touch
Vref
15kV ESD Low Power 4-Wire / 5-Wire Resistive
Interface
Screen
Page 10
Touch
Vref
in
ref-
ref+
Control
Touchscreen Controller with SPI Interface
ADC
in
POR
OSC
ref-
ref+
Control
GND
out
SX8652
ADC
POR
OSC
GND
Digital
Filter
SPI
out
SX8653
Digital
Filter
SPI
NIRQ
NRST (DFN only)
NCS
SCLK
DOUT
DIN
NIRQ
NRST (DFN only)
SCLK
DOUT
DIN
NCS
VDD
VDD
INT
DIO
CS
SCLK
MISO
MOSI
HOST
INT
DIO
CS
SCLK
MISO
MOSI
www.semtech.com
DATASHEET
HOST
SX8652