Wednesday, 4 July 2018

circuit protection - Why (not) put a resistor on FET gate?


While thinking of ways to protect a MOSFET one idea was to put an extremely high resistance in front of the gate: The idea being that current is never supposed to flow through the gate, so if some transient threatened the gate, the resistance would limit that current, possibly preventing the FET from burning out.


In fact, while researching MOSFET protection I came across this integrally protected product that includes in its features "internal series gate resistance," as shown on its diagram:


Protected MOSFET circuit


If this idea is correct, then the question is: Why not always put a megaohm resistor before the gate of any FET?


Or is there a practical reason that a gate resistor would not typically protect the FET? Or could it even have any adverse performance effects?




No comments:

Post a Comment

arduino - Can I use TI's cc2541 BLE as micro controller to perform operations/ processing instead of ATmega328P AU to save cost?

I am using arduino pro mini (which contains Atmega328p AU ) along with cc2541(HM-10) to process and transfer data over BLE to smartphone. I...