Datasheet

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ANALOG-TO-DIGITAL CONVERTER
Converter
-REF
+REF
+IN
-IN
AUX
SNSGND
AGND
X+
X-
SNSVDD
SNSVDD
PenTouch
R
IRQ
(1)
50kW
Y+
Y-
VREF PINTDAV
Preprocessing
Zone
Detect
Control
Logic
LevelShift
Data
Available
C3-C0
MAV
SNSVDD
AGND
TEMP1 TEMP2
TSC2004
SBAS408E – JUNE 2007 – REVISED MARCH 2008
Figure 28 shows the analog inputs of the TSC2004. 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.
(1) Untrimmed resistor; see the typical value in the Electrical Characteristics
Figure 28. 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.
The A/D converter is controlled by two A/D Converter Control registers. Several modes of operation are possible,
depending on the bits set in the control registers. Channel selection, scan operation, preprocessing, resolution,
and conversion rate may all be programmed through these registers. These modes are outlined in the sections
that follow for each type of analog input. The conversion results are stored in the appropriate result register.
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Product Folder Link(s): TSC2004