[sdiy] Zener diode wattage tolerances

John Speth jspeth at avnera.com
Mon Jul 9 19:03:02 CEST 2012

> The documentation tells that it's a zener diode (8.2V, 2W, 10%).
> Looking online, I'm finding 8.2V zener diodes but only with a 1.3W and
> or higher than 3W.  Nothing in the 2W range.
> I'm guessing a 1.3W diode should the job, right?

Without a schematic, we'd all be guessing too.  Please post the
schematic and maybe we can analyze it.  It should be simple enough.  Try
to compute the max reverse current at the zener voltage and compute
power (P=VI, you know V).  Add some reasonable headroom and you should
be good.

Remember it burned out for a reason (probably one you don't know).
Maybe the diode was underspecced and therefore it burned out.  It might
be worth the trouble to find a higher power diode and not take a chance
on a lower power one.  There's no performance downside to using a 3W
diode instead.


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