TSC2007-Q1
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SBAS545 –SEPTEMBER 2011
ANALOG-TO-DIGITAL CONVERTER
Figure 23 shows the analog inputs of the TSC2007-Q1. 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) A/D converter. The A/D architecture is based on capacitive redistribution architecture, which inherently
includes a sample-and-hold function.
VDD/REF
PENIRQ
RIRQ
50kW
90kW
Pen Touch
Control
Logic
MAV
C3-C0
GND
X+
X-
VDD
Y+
+REF
+IN
Y-
Converter
-IN
-REF
GND
AUX
GND
Figure 23. 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.
Copyright © 2011, Texas Instruments Incorporated
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