On 17 Apr 2007 at 17:57, David VanHorn wrote: > On 4/17/07, Brent Brown wrote: > > Yeah, I thought there would have been more comments about this. This > > issue has been simmering for ever. But things have got worse not > > better. Microchips message "don't use" the ESD diodes message is > > more than a little dissapointing. > > Well, we were NEVER supposed to be using those diodes, so all they are > really saying here is "We really MEAN IT !". I don't think it's that > the diodes have gotten worse really, it's just that people have been > cheating more and more, as we trend twoard having software people > designing hardware. > > I know it's a PITA, but that's what we get paid for... Correct, they've always only had an absolute maximum current rating for these diodes and never any ratings for normal use. They have covered their butts, and now more problems have shown up it has saved them. Interestingly the diode abs max current ratings appear to have increased from +/-10mA in the good old days to +/-20mA now, so perhaps it's not the diode size itself that's the problem. It seems to be where these currents flow in the rest of the chip that has the potential for ill effects. I contend though that good engineers NEED to be able to use these diodes. Lot's of arguments for it. Refer to the good old CD4000B CMOS logic chips and reccomended circuits for cool things you could use the diodes for. You could be right about the software people though..."what are those diodes there for, nobody needs them, do they???..." -- Brent Brown, Electronic Design Solutions 16 English Street, St Andrews, Hamilton 3200, New Zealand Ph: +64 7 849 0069 Fax: +64 7 849 0071 Cell: 027 433 4069 eMail: brent.brown@clear.net.nz -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist