Electrical – Mosfet Damage (ESD?)

esdmosfet

I have a few p-channel mosfets (IRLML6401) on PCB's, and it seems like the resistance between the gate and the source varies from 600 to 1100ohms. Obviously this resistance should be in the megaohms range, so I was wondering what could be causing this. They function otherwise, could it be a breakdown in the oxide barrier from ESD? The boards were assembled in china, so it's possible that this factory (we've had QC issues with other stuff) might not be using proper protection?

Best Answer

If you measured in-circuit, chances are you measured something else. Gates must never be exposed externally as a high impedance and often the driver RdsOn is only 10 to 100x RdsOn of output stage depending on desired risetime and current levels for high power PWM switches.

For ESD protection, read this. enter image description here