Dear Sir,
A customer is designing below circuit to measure the current when switch is on and COM voltage will be below 5V enough. However when switch is off, COM probably gets 20V thru 10Mohm resistance.
It is concerned about COM absolute max voltage and we would like to make sure if it is not good, and to have an advice what typically the circuit will be.
Best regards,
Masa
Footnote (4) of the datasheet's absolute maximum ratings table allows the COM voltage to be higher than V+ as long as the current through the ESD protection diode (from COM to V+) is lower than 50 mA (IK).
The 10 MΩ resistor restricts the current to less then 1.5 µA, so this circuit is OK.
If the current were too high, you would need either a 20 V-capable switch, or a circuit to clamp the voltage by shunting the current elsewhere (and in practice, the zener would be a TL431):
