JAJSGG2C October 2018 – June 2019 ADS125H02
Circumstances must be evaluated when an input signal is present when the ADC is unpowered. When the input signal exceeds the forward voltage of the ESD diodes, the diodes conduct resulting in backdrive of the analog power-supply voltage through the internal ESD diodes. Backdriving the ADC power supply can also occur when the power-supply is on. The backdrive fault-current path is illustrated in Figure 97. Depending on the power supply response during a backdrive condition, the ADC supply voltage rating may be exceeded. The ADC maximum-rated supply voltage must not be exceeded under any condition. One solution is to clamp the analog supply using a Zener diode placed across HV_AVSS and HV_AVDD.