Datasheet

ANALOG-TO-DIGITAL CONVERTER
Converter
-REF
+REF
+IN
-IN
PenTouch
Control
Logic
A[2:0]
MedianValueFilter
and
AveragingFilter
(MAV)
V
DD
GND
GND
TEMP1 TEMP2
R
IRQ
90kW50kW
AUX
GND
X+
X-
Y+
Y-
VDD/REF PENIRQ
Reference
TSC2008
www.ti.com .......................................................................................................................................................... SBAS406B – JUNE 2008 – REVISED MARCH 2009
Figure 24 shows the analog inputs of the TSC2008. The analog inputs (X, Y, and Z touch panel coordinates, chip
temperature and auxiliary inputs) are provided via a multiplexer to the Successive Approximation Register (SAR)
analog-to-digital converter (ADC). The A/D architecture is based on capacitive redistribution architecture, which
inherently includes a sample-and-hold function.
Figure 24. Analog Input Section (Simplified Diagram)
A unique configuration of low on-resistance switches allows an unselected A/D converter input channel to
provide power and an accompanying pin to provide ground for driving the touch panel. By maintaining a
differential input to the converter and a differential reference input architecture, it is possible to negate errors
caused by the driver switch on-resistance.
The TSC2008 uses an external voltage reference applied to the VDD/REF pin. The upper reference voltage
range is the same as the supply voltage range, which allows for simple, 1.2V to 3.6V single-supply operation of
the chip.
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Product Folder Link(s): TSC2008