At 09:57 AM 2/23/00 +0000, Alan Pearce wrote: > >Do you think I will have units dying in the field if I don't have the > >series resistor or diode there? I will probably add both to my next spin > >as it can't hurt too much, but I've got some concerns for prototypes going > >out the door next week. I would think that the protection diodes on MCLR > >wouldn't be hurt by the small amount of charge in a .1 or .01uF cap. > >If you do not put a diode in parallel with the resistor, you will almost >certainly have problems in the field. The protection diode inside the chip >will >almost certainly become low value resistor due to current discharge through it >if you don't. Worst case the diode will go short circuit. This is >precisely the >method early bipolar PROMS used for the fuses that you blew to code them! I'm sorry, but I have to disagree. The only way that the protect diodes will be damaged is if the current thru them is too high. That can happen only if VDD collapses too quickly. A couple of things might cause this: short VDD to gnd, PSU reservoir cap too small for the connected load current. One is not a normal condition, the other can be caught at the design stage. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 16 years of Engineering Innovation (1984 - 2000) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.