Re: High brightness white LEDs damaged by custom switcher

In article <463ade79$0$20595$ecde5a14@xxxxxxxxxxxxxxxx>,
Paul E. Schoen <pstech@xxxxxxxxx> wrote:

I'm sure they would "stand by their chips", but I think the
concern was that the software could go awry and damage could be
done before it could react. That's why I am considering a
separate fail-safe mechanism, such as a fast acting fuse, or an
NPN transistor that would turn on, when the voltage on the 1 ohm
sense resistor reached Vbe, and turn off the MOSFET.

Perhaps for development you could use a power NPN
that directly did a limiting clamp of the current
through the LED strings. Also a sensor that flags
when the NPN is conducting.

This would allow any fault to remain long enough
for investigation, without damaging the LEDs.

--
Tony Williams.
.

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