>Hey, all, I know this was already a discussion, but it was never answered >to my satisfaction... I have a PIC based card here that doesn't go >absolutely to 0 VDC when power is off... the PIC always screws up... Can >someone PLEASE suggest a simple-reliable solution? Can microchip put a >GND-shorting switch in their parts? > Shawn - I would look at a couple of things. First: see if this is just a matter of your filters holding charge. Hook a scope between VCC & GND, then touch a 100 ohm resistor from VCC to GND (with power off) and see what happens. If the supply nose-dives then recovers fairly slowly when you take the resistor off, that is most likely your problem. If the supply recovers very quickly, look to see if you have a signal coming in on one of the PIC pins. A quick and simple solution to the filter charge problem: connect a J175 JFET as follows: S to Gnd, D to Vcc (+5v), G to 100K resistor, other side of 100K resistor to unreg V+ (input of voltage regulator). What this does is monitor the UNREGULATED supply, when it drops below about 10 Vdc, the FET conducts and looks like a 120 ohm resistor load on the 5v supply. As soon as the unregulated supply climbs above 10Vdc or so, the FET turns off and looks like a very high resistance. One other thing: how large are your filter caps? If they are very large, you may also have a problem with the 5V supply RISE time (must be less than 50 mSec from 0.5Vdc to 4.5 Vdc). Dwayne Reid Trinity Electronics Systems Ltd Edmonton, Alberta, CANADA (403) 489-3199 voice (403) 487-6397 fax