TSC2102IDA datasheet(17/54 Pages) TI

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TSC2102

SLAS379A− APRIL 2003 − REVISED JUNE 2004

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Y+

X+

Y−

Y+ or X+ DRIVERS ON OR

TEMP1 , TEMP2

MEASUREMENTS

ACTIVATED

TEMP DIODE

HIGH EXCEPT WHEN

TEMP1. TEMP2

ACTIVATED

PINTDAV

DATAV

50K

TEMP1

TEMP2

Figure 13. PINTDAV Functional Block Diagram

In modes where the TSC2102 needs to detect if the screen is still touched (for example, when doing a PINTDAV initiated

X, Y, and Z conversion), the TSC2102 must reset the drivers so that the 50-k resistor is connected. Because of the high

value of this pullup resistor, any capacitance on the touch screen inputs causes a long delay time, and may prevent the

detection from occurring correctly. To prevent this, the TSC2102 has a circuit that allows any screen capacitance to be

precharged, so that the pullup resistor does not have to be the only source for the charging current. The time allowed for

this precharge, as well as the time needed to sense if the screen is still touched, can be set in the configuration control

This does point out, however, the need to use the minimum capacitor values possible on the touch screen inputs. These

capacitors may be needed to reduce noise, but too large a value increases the needed precharge and sense times, as well

as panel voltage stabilization time.

The function of PINTDAV output is programmable and controlled by writing to the bits D15−D14 of REG 01H/Page1 as

described in the Table 1.

TSC2102IDA Datasheet(PDF) 17 Page - Texas Instruments