We are using the AD7879 as a resistive touch controller and have run into a problem with ESD.
If the touchscreen we are using gets hit with ESD from the user's finger it will travel to the input pins of the AD7879 and cause the differential X/Y registers/pins to lockup, and the AD7879 will no longer receive touch data from the touchscreen. In this state the measurement control registers for touch pressure Z will show 0x0FFF and X Y will no longer change when the screen is pressed (I've confirmed that the touchscreen is not failed). However the AD7879 will still respond to commands and appears to work otherwise.
I tried putting the chip into reset, the reverting back to normal register settings but this does not cause the X/Y channel pins to recover. I also tried shutting down the internal ADC and oscillator for a time and no luck. Unfortunately this chip appears to have no mechanism to recover from a failure like this, and we cannot control the power rail to the AD7879.
Is there anything that can be done via software to get this to recover?
We've worked with STmicro and Semtec resistive touch controllers and have never had this problem despite similar ESD ratings. Could this be considered a defect of the AD7879?
