noiseless switching, CMOS supply rails

Paul R. Higgins higg0008 at tc.umn.edu
Thu Nov 11 00:36:40 CET 1999


I always thought modern CMOS could handle +/- 9V.  I think there's something 
about this in Don Lancaster's "CMOS Cookbook"; as long as you use the "B" 
(buffered) CMOS, you'll be fine with a +/- 9V supply.  And the "B" CMOS is 
pretty much all I've seen in the past 10 years, maybe longer.

I'm cringing a little here because I'm currently using 4053s and 4066s in some 
(dare I say it) t*be designs, where I need the increased headroom.  (Of course, 
the 150Vpp signal swing at the t*be plates is greatly attenuated before going 
through the CMOS switches!).  The +/- 9V is tightly regulated.

But definitely, +/- 12V will fry CMOS, at least last time I checked.

> > So far I've tried running the audio through a 4052 (2x 4ch mux) running
> > +/-12VDC supplies.  I tried this part first since it will switch
> 
>   Ack.  That is too much voltage for a 4xxx chip.  Better to use +/-5,
> +/-8 at most.  I've seen 4066s spontaneously combust at +/-12.

Thanks,
-PRH

_____________________________________________
Paul Higgins
email: higg0008 at tc.umn.edu
University College, University of Minnesota
_____________________________________________




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