Hey team,
Just curious, what do we specify as to what will happen if a voltage is applied on the input while the device is Vcc=0? I couldn't find anything in the datasheet except the following which details the off sequence rather than what happens while the device is off.
J&J is seeing that when inputting 4.7V they are seeing 2.5V on the output while the device is off
Thanks,
Cam
Hi Cameron,
Thank you for reaching out.
The absolute maximum rating of INx pins, as stated in datasheet, is "VCC + 0.5V". This means that when VCC = 0V, INx pins have to be < 0.5V otherwise the absolute maximum rating of these pins are violated and could lead to permanent damage. This is not unique to ISOW7842 rather the same for most GPIOs on most devices including MCUs. Hence, please request customer to not supply any signal at INx when VCC = 0V to avoid any permanent damages.
I am attaching below the schematic of input pin circuit from ISOW7842 datasheet. As indicated in the schematics, there is an ESD bypass diode between INx and VCC pins. When VCC is not supplied but INx pins are supplied, these ESD bypass diodes turn on and pass the voltage to VCC partially turning on the device. This leads to partial output voltage at VISO which is what customer seems to have seen. This is not reliable operation and the device operation can not be predictable. Hence, we request that customer doesn't operate device in such a method.
Let me know if you have any questions, thanks.
Regards,
Koteshwar Rao
