Resistors on parallel MOSFET outputs

Thread Starter

olphart

Joined Sep 22, 2012
96
Hi, I've seen low value (.05 - .5 ohm) high wattage resistors on the outputs of parallel MOSFETs.
Is this to balance the load? Is there a formula / rule of thumb on value & wattage?
I've just direct paralleled the outputs relying on positive temp characteristic to self balance and didn't have a problem.
Might be lucky ignorance... I may be overthinking this too.

Specific situ is 2 outputs of 13.5V @ 2.5A in 75 - 99% PWM, same power source.
My FETs are SI3421DV 30V @ 8A as high side switches and a MIC4126 gate driver.
Sure seems like simple parallel is ok, but I ask because maybe not. Thanks <<<)))
 

BobTPH

Joined Jun 5, 2013
3,825
They are typically used on BJTs to give a negative feedback to higher current and therefore balance the load.

You are correct that they are typically not needed for MOSFETs, for the reason you gave.

Bob
 
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