Interaction of high voltage supply with PIC12F629

Nov 22, 2004 2 Replies

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Richard Matsui 21 years ago

I am having trouble with PIC12F629 which is supplied by an isolated supply and M211 optoFET by Solid State Optronics also powered by same isolated supply at higher voltage which supplies our load at constant current. When supplying the PIC12F629 with an independent supply without the load being supplied the PIC12F629 operates correctly, but even when I supply the microcontroller separately, and the power supply for our loads is on I cannot turn on the input LEDs for the M211, i.e., the control outputs of the microcontroller does not drop to zero to turn on the optoFET, there is 1 K in series with 5 supply to provide turn on for the optoFET. Can anyone tell me what is going on.

Regards, Richard Matsui

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Gary Kato 21 years ago

This might have to do with the layout of your board. Obviously there's some interaction between your load and the control circuitry even though you are connected via an optical transistor.

I'm not a hardware guy but hopefully someone in the group can give some advice on where to look for problems.

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Dan 21 years ago

It's a bit hard to tell from your description, but if you've got isolated supplies, have a think about where the power and ground are for each isolated section. Remember that all the grounds aren't necessarily at the same level.

Dan

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