At 18.51 2011.12.27, you wrote:
>At 11:00 AM 12/26/2011, Electron wrote:
>
>>1) A nice sinusoid comes from a transformer.
>>
>>2) It passes through a diodes bridge, so it's rectified now.
>>
>>3) My PIC32 shorts it through an NPN transistor, effectively=20
>>exploiting the inductance of the secondary of the transformer. Yes,=20
>>it can withstand the resulting voltage spikes. :)
>
>Side question: are the diodes that make up the bridge rectifier fast=20
>or ultra-fast diodes?  If not, you will be seeing significant losses=20
>from those diodes.

No they ain't but now after Your post they will be. :D

If it matters: max switching frequency is about only 1000Hz though.

By the way, when are fast recovery diodes NOT necessary, talking about SMPS=
? Is there any situation ever when they can be safely avoided?

Thanks,
Mario


>
>dwayne
>
>--=20
>Dwayne Reid   <dwayner@planet.eon.net>
>Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
>(780) 489-3199 voice          (780) 487-6397 fax
>www.trinity-electronics.com
>Custom Electronics Design and Manufacturing
>
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