For anyone interested, I made a simple boost converter that boosts 14V up to 60V to power a 100W light bulb. The reason why I am posting this is to show what the reverse recovery time (trr) of a silicon diode looks like on a DSO. I used a FR304 (Fast Recovery Diode) found in a modern SMPS from a kitchen refrigerator.
Channel 1 (yellow trace) is the ripple voltage across the output capacitor. Channel 2 (blue trace) is the positive going edge of the gate voltage on a RFP50N06 MOSFET. You can see as the MOSFET tries to turn on the diode needs roughly 152nS to be able to block the change in polarity across it.
The light bulb is a 100W 240V type operating at 24.67% rated voltage. I cannot produce 240V out of my boost converter due to the 60V reversed biased Zener diode from Drain to Source in the MOSFET.
When one person suffers from a delusion it is called insanity. When many people suffer from a delusion it is called religion.
If you are wondering how I made the inductor take a look at this collage. I removed the ferrite core from an unused T.V.'s HV flyback transformer. The winding itself had its original iron core removed - it was from a model train power supply.
Reverse recovery of a diode
Posted - Sep 25 2010 : 11:43:55 PM
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