Diode replacement

Thread Starter

goodbyegti

Joined Apr 28, 2004
59
I have shorted diode in a switch mode power supply.

It is a 6AMP fast recovery type and forms part of a rectifier immediately after the mains input.

What is the difference between fast and standard recovery and am i ok using a standard recovery replacement?

I have my guesses but would like to hear your opinions.

Thanks,
Doug
 

beenthere

Joined Apr 20, 2004
15,819
Hi,

A standard recovery diode will blow up almost instantly. Fast-recovery types have very low junction capacitance, allowing them to come out of conduction very quickly. Get the right replacement.
 

Thread Starter

goodbyegti

Joined Apr 28, 2004
59
Out of interest when would you use a standard recovery rectifying diode?

When you are using low frequency AC? I presume you would work this out from the time constant?
 

mrmeval

Joined Jun 30, 2006
833
Use standard recovery for frequencies within it's specification. :)

Normally AC is fine if the voltage and wattage are in range.
 

Thread Starter

goodbyegti

Joined Apr 28, 2004
59
I checked and the 'standard recovery diode' has specifications very similar to the old 'fast recovery diode' There is a very small difference in junction capacitance (50pf). I suppose fast recovery is more important on the output side of a SMPS when there's very high frequency. I couldn't find a suitable fast recovery diode so went for the standard one. Hopefully it won't blow up!
 
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