Hi,

It is a good practice to have the PIC powered by a separate regulator and the rest with another one. When the internal pull-ups are enabled and there is a glitch in the PS then interrupts can occur without possibly resetting the chip through brown-out detect. I have found that in noisy environments with tens of MOCB and contactors switching in an out there are false interrupts due to interference. I revised my PCBs and redesigned the PS. It did improve but was never totally fool proof. Normally the PICs are very stable from EMI standpoint. So the only way out was software. I introduced a short delay just entering the interrupts and checked that if the PIN was still high (or low). Since the interrupt is predictable you can detect if it was a glitch. Then simply clear the flags and quit from the interrupt. BTW I use asm interrupts.

Hope this helps.

Regards

Sougata