Datasheet
TSC2101
SLAS392D− JUNE 2003 − REVISED MAY 2005
www.ti.com
37
Y+
X+
Y−
ON
Y+ or X+ DRIVERS ON OR
TEMP1 , TEMP2
MEASUREMENTS ACTIVATED
TEMP DIODE
HIGH EXCEPT WHEN
TEMP1. TEMP2
ACTIVATED
PINTDAV
DATAV
TEMP1 TEMP2
AVDD1
50 kΩ
Figure 28. PINTDAV Functional Block Diagram
In modes where the TSC2101 needs to detect if the screen is still touched (for example, when doing a PINTDAV
initiated X, Y, and Z conversion), the TSC2101 must reset the drivers so that the 50 KΩ resistor is connected.
Because of the high value of this pull-up 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 TSC2101 has a circuit
that allows any screen capacitance to be precharged, so that the pull-up 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 register D5−D0 of register 05H/Page 1.
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 will increase 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 control
register 01H/Page 1 as described in the Table 4.