At 12:06 AM 5/8/02 +0300, Peter L. Peres wrote: > > TPICxxxBxx > >B and other revised silicon versions of nearly ALL chips I've ever seen >(except standard 4xxx(x) CMOS where the B means buffered - see below) >have higher speed and lower noise immunity than the original chips they >are supposed to improve. The reason is die shrink which causes higher >speed operation and much steeper thresholds usually, and this means >glitches and critical layout will kill your design. Normally I'd agree with you, Peter - but I'm afraid I have to disagree this one time. TI has done something rather silly: they have grouped similar but NOT identical parts with the same part number. The TPIC6595, TPIC6A595, TPIC6B595, TPIC6C595 all have DIFFERENT pinouts! The two that are the most similar are the '6595 and the '6B595: pins 1 & 20 on the 6B595 are not used but are power GND on the '6595. So a layout that is designed for the '6595 will work for the '6b595. The '6b595 parts cost less than the others - that's why I started out using them. But since the only difference between the 2 variants was the extra ground pins, I did my layouts so that I could use either. But take a close look at the glitch test that I described in my earlier post. My layout was not an issue: the pins on the device under test didn't go to any traces! They were tied to the chip's ground pin as directly as could be managed. And the chip still glitched. Substitute the '6595 and no glitches. dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' 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. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads