Resistors on parallel MOSFET outputs

Thread Starter

olphart

Joined Sep 22, 2012
113
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
6,095
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
 

Thread Starter

olphart

Joined Sep 22, 2012
113
Thanks for the verify Bob. I'd rather ask a nooby question than think I know and be wrong. <<<)))
 
Top