[sdiy] CMOS schmitt trigger question

Ken Stone sasami at hotkey.net.au
Sat Dec 22 01:55:33 CET 2001

Series is simply because the designer wanted a non-inverting schmitt input,
so he used a spare gate from the package to re-invert.
As already stated, parallel is to increase the output drive available. 
Sometimes schmitt gates are used as general purpose, simply because a gate
or two required schmitt inputs, and the rest of the gates in the package
were used as ordinary inverters.

>You can parallel gates in the SAME CMOS package...
>for higher current drive vs larger input capacitance
>Don't do this with different packages... the matching
>is not good enough.
>I have usually not seen this done with the schmitt
>trigger type gates. I don't know if the gate to gate
>matching is as good ???
>H^) harry
>--- media at mail1.nai.net wrote:
>> I've seen schmitt triggers (eg. CD40106) used in
>> series and parallel in a
>> number of shematics.  I'm thinking two in series may
>> be one way to clean up
>> a signal, but I have no idea what two in parallel
>> would do.  Any ideas??
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Ken Stone   sasami at blaze.net.au  
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
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