Hi Guys
thanks for all the help, I went to IRF website like Phil and Veronica
suggested and found what I required.
this is what IRF say:
        for a triangular wave form the Isquared*R losses are 32% more than
for a rectangular wave form and give the formula to calculate Irms as Irms =
Ipk* square root of (duty cycle/3).
so from there I used this value to calculate the power dissipated: P=
Irms*Irms*Rds.
which gives me a value close to what I was expecting 6.7W, does this seems
correct ?
What about the Switching losses that Russell mentioned with 36V can I ignore
them?
thanks
        Luis


-----Original Message-----
From: Eisermann, Phil [Ridg/CO] [mailto:peiserma@RIDGID.COM]
Sent: 03 November 2003 21:48
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE:]calculating power dissipation on transistor


> -----Original Message-----
> From: Veronica Merryfield [mailto:veronica.merryfield@TESCO.NET]
> Subject: Re: [EE:]calculating power dissipation on transistor
>
>
> For Luis et al
>
> As far as I can remember, IFR and the like  do some good app notes on
> calculating the power disipation during transient an steady
> state. It i
> worth looking on their web site.
>

The first two app notes on IRF website to read are AN949 and AN936.
After you read those, you should have a better idea of what else
to ask about.

In addition, EDN (i think it was EDN) recently ran a story about
calculating switching losses in MOSFETs.

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