I'm using this IC (https://www2.mouser.com/datasheet/2/609/ADM1270-878589.pdf).

This IC controls the GATE of a pmos. I'm thinking about using this MOSFET (https://www2.mouser.com/datasheet/2/389/sts10p4llf6-956791.pdf).

  • The GATE pin on the IC has a typical current value of 25uA.
  • MOSFET gate has a fair amount of charge (Total gate charge = 34nC) and it has Input capacitance (Ciss)= 3525 pF.

Do I need to use a Resistor to limit the current out of the pin? How do i proceed?


Open the datasheet of the ADM1270 and scroll to page 14 and look at the Typical Application circuit:

enter image description here

I do not see any gate resistors.

A quick search in the text also makes no mention of gate resistors.

The typical application where gate resistors are needed are in fast switching applications like DCDC converters. There a gate resistor can help prevent current spikes by limiting the current to the gate and making the on/off transistions a bit slower.

This ADM1270 is not continously switching, in fact, in normal operation it doesn't switch at all as long as the input voltage and current don't exceed a certain value.

So the MOSFETs aren't used in a way that a gate resistor is needed. Chances are that the IC will already limit the gate current to a safe value anyway.

So no: gate resistors aren't needed.

  • \$\begingroup\$ Thank you for your answer! I thought so, but I was not sure what is the standard: is the protection of the pin my problem to solve according to the pmos choice or does the datasheets states the requirements (and ignores them when not needed, similar to this case) \$\endgroup\$ – David Ribeiro Oct 4 '18 at 14:29

No, you don't need a resistor (and the application diagrams don't show one). The chip itself limits the current into/out of the MOSFET gate.


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