Selecting rectifier diodes for high frequency or SMPS supplies?

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How do we select parameters to arrive at a reasonable compromise?
What parameters and attributes are required for HF rectifying?
What parameter requirments change as currents and voltages change?
.../...
So what other factors are important in selecting rectifier diodes?
There are no universal rules: it depends on the topology, the frequency, the operating mode, etc.
Sometimes, you can even use slow diodes: in a discontinuous mode flyback converter for instance. There are even cases where a slow diode is beneficial.
You have to analyze each case specifically, and decide what are the important parameters, and compute quantitatively their actual impact on efficiency
 
Besides efficiency, an other obvious parameter to the equation, that needs therefore not to be mentioned, is probably EMI.
Universally for this obvious parameter - the faster (again) the diode, the better...

There are exceptions to that, unfortunately. (not the EMI statement of course, that is absolutely correct.)

When I was testing fast and ultrafast recovery diodes, my very high bandwidth testing setup spotted an interesting phenomena. Some diode types recovered very nicely, the recovery tail well behaved. Some diodes held onto the reverse current until the very last instant, then the current collapsed in under 250 or so picoseconds. Since the TRR specification reads half amp forward/1 amp reverse/1/4 amp threshold, how the diode meets that can indeed vary quite a bit.

Even in the 5 to 15 nSec range, there are hard and soft recovery devices. Most humans do not know how to design the circuit topology to prevent ringing in the Ghz range, or even in the Mhz range. If the diode snaps off, the result could be some nasty broadcasting.

To me, specifying soft recovery fast units makes sense for audio applications.

jn
 
I did see this thread, I have to make choises what concerns a resoant smps for multiply voltages from one is 320 volts, two are 120 volts bothe max 250mA and 15 volts 15 ampere.

I can not well deside what kind of rectifier to use, what is best, I use single coils.

Supply is for tube hybdrid amp, and go use two, one for the mosfet 2 x 65 volts 15 amps open loop, (need no regulation, tube part do need.)

Thanks for advise in advance.

regards
 

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