Datasheet

Program Description
3-15
Operation
J Panel Voltage Stabilization Time
This is the time that the TSC2100 allows for the touch screen to settle after
turning the drivers on.
J Precharge Time
J Sense Time
These two parameters are the time allowed to precharge the touch panel
capacitance and then sense to see if the screen is touched. For more de-
tails on these parameters, refer to the TSC2100 data sheet.
J Average/Median
There are two ways to reduce noise effect to the ADC result. One is aver-
aging where 4, 8, or 16 readings are averaged, and another option is to
find the median value among 5, 9, or 15 readings.
Note that these settings apply to all operations of the A/D converter, not just
the touch screen operations. Thus, resolution and averaging can be changed
to increase accuracy in the data acquisition functions.
3.5.3.2 Reference Section
The touch screen function is always performed using a ratiometric mode; for
all other A/D functions, a reference voltage is needed for the A/D converter.
Figure 3−6 shows this section with the TSC2100’s internal reference chosen.
This reference voltage can be set to either 1.25 V or 2.5 V.
The internal reference powers down between conversions to save power. Us-
ing the Powered at all times checkbox, this can be overridden and the refer-
ence does not power down. If the reference is allowed to power down, the
TSC2100 then must allow a delay time for the reference to power up when a
conversion is to take place. This delay time can be set using the slider in this
section.
If an external reference is to be used, it can be selected as shown in
Figure 3−7. The value of the external reference should be entered in the text
box shown.