Converter

-REF

+REF

+IN

-IN

PenTouch

Control

Logic

C3-C0

MAV

V

DD

GND

GND

R

IRQ

90k

W

50k

W

AUX

GND

X+

X

-

Y+

Y

-

VDD/REF

PENIRQ

TSC2017

SBAS472 – DECEMBER 2009

www.ti.com

ANALOG-TO-DIGITAL CONVERTER

Figure 23 shows the analog inputs of the TSC2017. 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.

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.

16

Submit Documentation Feedback

Copyright © 2009, Texas Instruments Incorporated

Product Folder Link(s): TSC2017