In my personal experience, modern 4000 and all 74HC/HCT are not as sensitive to ESD, as the older 4000, 74Cxx. TTL and Schottky series do not contain gate dielectrics and all inputs and outputs have quite low impedance. Those devices are vera hard to kill by static discharge, but I would not dare to say that it will be impossible!
Except for protecting against ESD the foam is a good mechanical protection for device legs, but you could also use special boxes of conductive plastic to store your CMOS chips. The voltage range of the 74HC series is specified as +2-+6V, 74HCT spans +4.5-+5.5V. With the trend of going to ever lower supply voltages I'm not aware of a replacement for the 74C above +6V. Uwe. "Syd Levine (AnaLog)" wrote: > > Greetings List: > > I have some questions about logic families I hope some of you gurus can help > me with. I have been reorganizing our stock of logic chips for the last > couple of days and realized I was not really sure about some assumptions I > have made over the years. > > Static Sensitivity - I think DTL, RTL, and TTL chips are relatively > insensitive to static, so can they be safely stored loose in plastic parts > cabinet drawers? I assume 4000 series and 74Cxx CMOS chips are very static > sensitive and should be inserted in conductive foam in the plastic drawers. > But what about the Schottky families like 74Sxx, 74LSxx, and 74ALSxx, are > they static sensitive? And what about the newer CMOS families like 74HCxx, > 74ACT, etc.; are they as static sensitive as the original CMOS families? > > Compatibility - I work on several circuits that use 74Cxx chips (actually, > the 54Cxx mil spec versions), and a few of them are hard to find now, > especially the 74C221. Some of these circuits are running the 74Cxx chips > at 5 volts, and some at 10 to 15 volts. Am I correct that the 74HCxx chips > will probably replace the 74Cxx chips only in the 5 volt applications? Are > there any logic families other than the 4000 series and the 74Cxx CMOS chips > that can be powered with 10-15 volts? > > Thanks in advance. Sorry for so many questions. > -- Author: Uwe Zimmermann INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
