Mosfet burn

jegandren · 24th July 2008, 08:16 AM

hi all,

Based on the attached circuit AC - DC circuit, before conecting the PFC ic and the MOSFET and the i have connected my design...but without connecting the PFC ic . MOSFET( IRFP450) and fast recovery diode. I got a pure DC voltage about 320V for a load of 150 ohm's. But what i dont understand here is when i connect the MOSFET ...without giving any signal to the gate it should be functioning as the same, because current don't flow from drain to source when there is no signal to the gate. Here the case is my mosfets keeps burning as if it is shorted. please advise

Eva · 24th July 2008, 09:24 AM

There is always some leakage from drain to gate so if you leave the gate open (or in an high impedance state) and apply some voltage to the drain, the MOSFET will tend to turn on by itself.

The gate has to be pulled low to source potential when the MOSFET is intended to be turned off.

jegandren · 24th July 2008, 05:06 PM

Heloo eva,

Thank you very much for your tips. It works.

24th July 2008, 09:24 AM	#2
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	There is always some leakage from drain to gate so if you leave the gate open (or in an high impedance state) and apply some voltage to the drain, the MOSFET will tend to turn on by itself. The gate has to be pulled low to source potential when the MOSFET is intended to be turned off. __________________ I use to feel like the small child in The Emperor's New Clothes tale

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24th July 2008, 05:06 PM	#3
jegandren diyAudio Member Join Date: Feb 2008	Heloo eva, Thank you very much for your tips. It works.

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