At 09:46 AM 2/8/2006 +0100, you wrote:
> > > Sideline: does a diode spec mention a maximum *forward* voltage?
> >
> > No, but a maximum forward current. As long as you stay below that, the
> > forward voltage is in normal ranges.
>
>In a static situation yes, but the issue here was that the forward
>voltage might rise so fast that the diode does not have time to turn on
>so you'd get a large forward voltage which might destroy the diode. I
>doubt the reality of this scenario, but it is what (this part of) the
>discussion was about.

The forward recovery time of a slow-as-molasses diode such as the 1N4005 is
a couple hundred ns at 100mA typically. So, the voltage might overshoot a
a volt or less with a typical edge from an inductor. No big deal.
1N4006,7 use a different die and are about 50% slower. Reverse recovery of
these slugs is in the microseconds.

On the 1N4148, with 50mA switched, 20ns rise time, you'll see less than 2.5V
forward peak forward voltage (maximum guaranteed).

None of this is at all significant unless things are right at the edge.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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