Re: MOSFET GOT XTREMELY HOT
- From: "Mook Johnson" <mook@xxxxxxxx>
- Date: Thu, 8 May 2008 20:38:19 -0500
<bigcaboy@xxxxxxxxx> wrote in message
news:323f0cda-eec3-446b-a933-bcbea773ed4b@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I just used the IRFP044 as picture shows but it gets extremely hot at
8A DC. It buzzed and I saw a sine wave stacked DC at Gate. Is't
caused by the linear region resistance?
got a picture from other website:
http://www.unsp.com.cn/app/pic/2006526115419.jpg
or any other reasons?
Thanks,
Powerboy
It all depends on what you are trying to do. If you're making a 8A current
source then the mosfet will be operating in the linear reagoin and will get
hot.
Mosfet only run cool whne fully saturated or off.
The suggetions on making connection a cap from the output to to the - input
and a resistor in series with the -input is to allow direct feedback at high
frequencies to the OPAMP. You are getting oscillations because at those
frequensies you have significant phase shift between the 10K resistor and
the MoSFETS transfer function to cause positive fedback instead of the
desired negative feedback.
Doing this will slow the outputs response to the input command. you can
reduce the capacitance until it starts to honk again the increase it some to
get into a safe reagon of operation (FOR THAT MOSFET).
.
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