SX8652ICSTRT Semtech, SX8652ICSTRT Datasheet - Page 11

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

3.2. Channel Pins
3.2.1. X+/BR, X-/TL, Y+/TR. Y-/BL
Figure 7. Simplified diagram of touchscreen pins
3.2.2. AUX/WIPER
Figure 8. Simplified diagram of AUX/WIPER pin
3.3. Host Interface and Control Pins
The SX8652 host and control interface consists of the SPI interface with NIRQ and NRST.
3.3.1. NIRQ
Figure 9. Simplified diagram of NIRQ
Revision V1.6/July 2010
©2010 Semtech Corp.
ADVANCED COMMUNICATIONS & SENSING
HOST
VDD
AUX
X+
X-
Y+
Y-
NIRQ
VDD
VDD
R
chn
IRQ
Touch Screen
Interface
Control
ADC
Control
15kV ESD Low Power 4-Wire / 5-Wire Resistive
Page 11
Touchscreen Controller with SPI Interface
The SX8652's channel pins directly connect to standard
touch screen X and Y resistive layers. The SX8652
separately biases each of these layers and converts the
resistive values into (X,Y) coordinates.
The channel pins are protected to VDD and GROUND.
Figure 7 shows the simplified diagram of the X+, X-, Y+,
Y- pins.
The AUX/WIPER has 2 functions.
With 4-wire touchscreen, it is a single ended input for the
12 bit ADC with an input range from GND to VDD.
It can also be used to start the channel acquisition.
With 5-wire touchscreen, it is the sense channel of the
touchpanel.
The AUX/WIPER pin is protected to VDD and
GROUND.
Figure 8 shows a simplified diagram of this pin.
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). NIRQ provides an interrupt to the host
processor when a pen is detected, or when
channel data is available.
As shown in Figure 9, the NIRQ pin does not have
protection to VDD.
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SX8652