Power dissipation problem

I want to drive a MOSFET gate with a transistor coupling like the one on the schematic. To get at least 1.5A to the gate the resistor must be 13R with a 20V power supply. The problem is therefore the power comsumption in the 13R resistor - 30W! What to do?

Electronics4you said:

I want to drive a MOSFET gate with a transistor coupling like the one on the schematic. To get at least 1.5A to the gate the resistor must be 13R with a 20V power supply. The problem is therefore the power comsumption in the 13R resistor - 30W! What to do?

Click to expand...

Well you either use or build a gate driver. You need a second transistor to pull it up instead of a pull up resistor. Usually you only use 12V to drive the gate as many are only 15V ratings.

You do not say what you are trying to do. If you did I might be able to make other suggestions. For instance at high voltage and current IGBTs are much better than FETs...but not at high frequency.

D.

hi e4you,

Why do you want to switch 1.5A into a MOS FET gate ?.

The gate of most FET's is voltage driven.

Regards
EricG

ericgibbs said:

hi e4you,

Why do you want to switch 1.5A into a MOS FET gate ?.

The gate of most FET's is voltage driven.

Click to expand...

Don't even go there!!!!

It's to charge the gate capacitance quickly, essential if you want fast switching.