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High side MOSFET poblem

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Ehab Abdalla

Newbie level 6
Sep 14, 2012
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I'm trying to drive MOSFET (IRF644) as a high side switch,input voltage is 220 Vdc and the frequency ranges from 0HZ to 100HZ and I don't want to use any IC like ir2112 or ir2110 just need to control the MOSFET with transistors,capacitors and resistors.
I have found a circuit which I tried practically and worked for 48 Vdc but when I changed the input to 220 Vdc everything went wrong , so I need help if anyone has other schematics or help in modifying the attached circuit to work with 220 Vdc

Grbniiii XD.JPG

Well, without looking too closely, I'd say your first problem is that the bipolar transistors you are using probably blew up. They are rated for 40V and 60V; I am sure they were very unhappy to see 220V.

Also, R2 is going to have to be rated for about 5W (at 100% duty cycle).

You need to go through the entire circuit and see what kind of stresses are going to be present. I'm not sure this is the right circuit for the job.

I have changed the bipolar transistors to be able to withstand 250V but once i plug the power,the capacitors (400V rated) blow up

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