TSC2007 a touchscreen.

[Jirka]

In some applications, external capacitors may be required across the 
touch screen for filtering noise picked up by
the touch screen (for example, noise generated by the LCD panel or 
back-light circuitry). The value of these
capacitors provides a low-pass filter to reduce the noise, but creates 
an additional settling time requirement when
the panel is touched. The settling time typically shows up as gain error.
To solve this problem, the TSC2007 can be commanded to turn on the 
drivers only, without performing a
conversion. Time can then be allowed to perform a conversion before the 
command is issued.

(datasheet str. 14)

Jirka