TSC2004_12 Datasheet, PDF (14/58 Pages) Burr-Brown (TI) – 1.2V to 3.6V, 12-Bit, Nanopower, 4-Wire

TSC2004
SBAS408E – JUNE 2007 – REVISED MARCH 2008
www.ti.com
Touch
Screen
1.6VDC
1mF
0.1mF
SNSGND
1mF 0.1mF
DGND
1mF
0.1mF
AGND
1.6VDC
1.2kW
Host
1.2kW Processor
X+
Y+
TSC2004
X-
Y-
PINTDAV
RESET
SDA
SCL
GPIO
GPIO
SDA
SCL
(PINTDAV is optional;
software implementation
polling of the Status
register is possible)
Auxilary Input
AGND
Figure 24. Typical Circuit Configuration
TOUCH SCREEN OPERATION
A resistive touch screen operates by applying a voltage across a resistor network and measuring the change in
resistance at a given point on the matrix where the screen is touched by an input (stylus, pen, or finger). The
change in the resistance ratio marks the location on the touch screen.
The TSC2004 supports the resistive 4-wire configurations, as shown in Figure 25. The circuit determines location
in two coordinate pair dimensions, although a third dimension can be added for measuring pressure.
4-WIRE TOUCH SCREEN COORDINATE PAIR MEASUREMENT
A 4-wire touch screen is typically constructed as shown in Figure 25. It consists of two transparent resistive
layers separated by insulating spacers.
Conductive Bar
Transparent Conductor (ITO)
Bottom Side
Y+
X+
Transparent
Conductor (ITO)
X-
Top Side
Silver
Ink
Y-
ITO = Indium Tin Oxide
Insulating Material (Glass)
Figure 25. 4-Wire Touch Screen Construction
The 4-wire touch screen panel works by applying a voltage across the vertical or horizontal resistive network.
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