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ANALOG-TO-DIGITAL CONVERTER

Converter

-REF

+REF

+IN

-IN

PenTouch

Control

Logic

C3-C0

MAV

V

DD

GND

GND

R

IRQ

90kW

50kW

AUX

GND

X+

X-

Y+

Y-

VDD/REF

PENIRQ

TSC2007

SBAS405 – MARCH 2007

OVERVIEW (continued)

Figure 23 shows the analog inputs of the TSC2007. 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 (A/D) converter. The A/D architecture is based on capacitive redistribution architecture,

which inherently includes a sample-and-hold function.

Figure 23. Simplified Diagram of the Analog Input Section

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-resistances.

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