Maxx VCS - Changes/cmos

[Martin Czech]

> Well, my (20 years old) RCA CMOS Databook says 20V as absolute maximum supply 
> voltage for all 4000-series chips. Has that been changed? 
> 
Well, I think the problem with CMOS is that there are many
manufacturers. You can only know the pinning and functionality by the
device number (CD4xxx). Parameters like Vdd max, propagation delay
etc.  depend much on the process, which is not defined by the device
number.  To be shure one needs to know the manufacturer of the device
and the codes that are used for different flavours of cmos. So far I
know only of one thing that is commonly used: B stands for buffered and
UB for unbuffered. But even for this property exceptions can be found.
Most of the CD4xxx series have a recommended Vdd of 15V however. If the
databook says absolute maximum 20V, this means that the part may
withstand this exceptional high voltage for some time, but you are out
of the recommended operating area ! Lifetime etc. may decrease.  I
wouldn't do this. Better keep to recommended operating conditions,
because the parts are only tested for these.

m.c.