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PMP8363 85VAC-265VAC Input, 5V@2A Eco-Charger - Snubber Diode

Konstanty Matuszak
Prodigy 40 points

Hello

I am analysing this design ( http://www.ti.com/tool/PMP8363?DCMP=gma-gtd-ecochg&HQS=gma-gtd-ecochg-bhp#Technical%20Documents ) and one thing hit me: why there is standard recovery rectifier in snubber? I understand this is quasi-resonant design, but still some snubbing is needed. Can MRA4007 handle high frequency operation?

Regards

Konstanty Matuszak

  • 0
    Guru 55913 points

    The MRA4007 was lab tested 20kHz (50us) square wave @2 amps. Who knows what higher frequency it can be subjected to and still recover from a reverse cycle unscathed.

     

  • 0 in reply to Genatco
    Prodigy 40 points

    I see datasheet diagrams, still selection of such diode is strange for me. It has no rated reverse or forward recovery time. PSU switching frequency is also far higher than 20kHz mentioned in datasheet.

  • 0 in reply to Konstanty Matuszak
    Guru 55913 points

    It has no rated reverse or forward recovery time:

    Possibly because this is a generic slow reacting diode the switching time is a mute point. Fast switchers typically brag about how fast they can recover (4-35ns) especially when PRV is very high.

    When in doubt switch it out! 

  • 0 in reply to Genatco
    Prodigy 40 points

    Did you made measurements? I've seen many designs with fast or ultra-fast diodes like MURA160 or FR153, while never with standard recovery. Spike due to prolonged switching on is most interesting thing to see in this application.

    Anybody scoped it? Also variation from element to element is fancy thing - nobody guarantees switching times 1N4007 and its clones.