Jim Wilkins wrote:
"Martin Eastburn" wrote in message
...
On bridges and rectifiers in general.

If the reverse voltage is high then the other specs are based
on the reverse voltage. e.g. the leakage currents and such.

It is generally best to buy the voltage range you use or just
higher. Those are made for that service.

Martin


With Schottky diodes increasing the reverse voltage rating costs a
higher forward drop, but I don't remember hearing that about silicon
junction diodes when I was a lab tech at Unitrode. The forward
properties of the 1N4001 - 1N4007 series are all listed as identical:
http://www.vishay.com/docs/88503/1n4001.pdf

I didn't get any good hits from a search on diode recovery time vs
PRV.

The voltage rating doesn't factor in when using a junction as a
temperature sensor, unless they lump it into "ideality":
http://cds.linear.com/docs/en/applic...ote/an137f.pdf
That's a very sensitive measure of a junction's DC properties, though
not capacitance and recovery time. It's useful when checking out new
ICs in the lab if the connections to a junction are externally
accessible or can be probed.

I worked on a tester that used base-emitter voltage drop to measure
and control the temperature of a socketed power transistor, without a
heatsink. The only active correction in the op-amp control loop was
subtracting the intrinsic resistance of the emitter multiplied by the
collector current.

The life of a transistor was very short above 175C, and only a few
seconds as it approached 200C. I have a lot of experience
overstressing and breaking things.

I was called in on that project to find out why the power supply
shorted when the device polarity was reversed. The problem was very
efficient relays whose high inductance kept them pulled in by current
circulating through the clamp diode for about 15 seconds after they
were turned off. The engineer knew the theory well, but not so much
the practice.

Very early silicon were similar to selenium, in that they stacked low
voltage diodes to get the required PIV. Microwave oven diodes still do this.

Early color TV sets switched from a 1V2 tube to a long thin stack of
selenium pellets in the focus circuit. They had a very high forward
drop, and could not be tested with the equipment sold to TV shops.


--
Never **** off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)