I once had to work on a recall for a product that the previous engineer didn't catch. We had PIC16C73's running at 20MHz. A short brown-out to 4.4V caused the processor to lock up. Unfortunately, the internal brownout doesn't trip until a little bit lower. Guess what! Be sure to include a 4.5V reset circuit on your design!!! Andy David VanHorn on 04/12/2000 11:14:16 AM Please respond to pic microcontroller discussion list To: PICLIST@MITVMA.MIT.EDU cc: (bcc: Andrew Kunz/TDI_NOTES) Subject: Re: Why isn't my crystal oscillating? -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 >Oh bugger. I had naively taken it for granted that the quoted' wide >operating range of 2.0 to 5.5V' was for all operating speeds... and looking >at the datasheet it seems this isn't the case.. > >According to the datasheet, I'll need at least 4.5V. I think you may have >hit the nail on the head! It may not be the answer you wanted, but it sounds like an answer. CMOS logic gets slower with lower supply voltages, so you always have to watch for that. -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.2 for non-commercial use iQA/AwUBOPSSyIFlGDz1l6VWEQL7gwCg9fyJBd1x9EyslShPZ+5rF1+Ymp8AnRb5 +cIzwveGvDBtBs/YOeFH/YhI =puyU -----END PGP SIGNATURE-----