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Flyback with output diode with trr = 250ns

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cupoftea

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Hi,
Just seen a low power (bias) flyback SMPS, vin = 200Vdc, (RM6 bobbin) it has a RGL34J-E3/98 diode on its main output (12V)....with trr = 250ns.
Why pick such a slow one when there are loads with trr <= 75ns?

RGL34J-E3/98


{Incidentally, the RCD clamp diode is ACURN105-HF (trr = 75ns)
ACURN105-HF

Also, the Aux coil diode is BAV102....which is a UF diode, trr=50ns
BAV102

}

And BTW, why are all these three diodes different?....for a low power bias flyback, surely you would just use the same part in each place?
__________________________________
Another point is that its isolated, and the Aux coil is used with a potential divider to get regulation for the main output.......Aux coil is regulated to 12V......And main (secondary) output has a 13V zener on it (BZV55-C13).....couldnt that be a bit precarious with such rough, primary side vout regulation?......there is no sandwiching in the transformer.

BZV55-C13 is only 500mW rated.
 
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