Re: Help, processor reset when power on large transformer.
Rock wrote:
> I've got a simple pic based controller that turns on power via a relay
> to a 1000W transformer used for high energy lighting. When I turn the
> power on the processor ends up reseting. I've traced this back to about
> a 2 micro second low going pulse break in the power to the processor.
> Adding capacitance, and even putting in diode based filter has not
> helped. I'm guessign the emf field from the transformer is causing
> inductance via the wires on the prototype (this design has not gone to
> board yet). The power glitch happens on the output of the LM2940 5 volt
> reg I'm using, and it is supplied by a 24 volt DC off line power supply
> that doesn't glitch. I've tried various caps on the regulator with no
> help. I'm switching the power anywhere in the AC cycle, and it doesn't
> always reset. Anyone have any ideas of things to try?
>
> I rewrote the software so that a reset is part of the normal power on
> and off sequences for this device, if it happens. While this works I
> find it a real cop out.
Sounds like it's possible poor pcb design ( loop areas for example ) or
lack of attention to general EMI issues.
There's tons of stuff written about how to do it right but I guess you need
to read some.
You won't be the first to experience this kind of issue for sure.
Graham
.
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