Hello John,
Do you talking about the capacitance of a 4-wire resistive touch panel, right? We are not a touch panel manufacturer but rather design and produce the controllers for touch panels or touch screens or touch sensors.
In our TSC device datasheets, we had not specified any limitations on the max or min capacitance, because the capacitance on the touch panel (mainly equivalent capacitance on the analog touch input lines, X+/X-/Y+/Y-) affects the touch data’s throughout capability, which is decided by not only the capacitance from the touch panel but also the (internal and external) capacitance on the analog interface lines; which is also affected by the touch panel’s resistance; and which is very much application specified (some applications require rather low rate and others requires higher rate, typically from 50 sets per second to 500 sets per second).
If the equivalent capacitance at the X+ or Y+ line is around 100nF or 0.1uF, refer to the Figure 3 in the application report SBAA155A, the touch coordinate data throughout rate from be from 100 sets per second to 1000 sets to second (affected by the touch panel resistance).
Anyhow, may you detail what is the current issue with the customer, so that we can help them to select a proper TI TSC device?
Best regards,
Wendy F.