Current-limit resistors on 74HC14 output towards PIC 16F MCU

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H treboR

Joined Jun 6, 2024

Are current-limiting resistors required on the output of a TC74HC14 schmitt trigger towards the input pins on a PIC 16F MCU?

I googled, but don't seem to get any hits on that subject.



Joined Feb 24, 2006
A single CMOS input, like the ones on a PIC 16F device, are normally very high impedance and consume very little current from the driving source. If on the other hand you try to drive a large number of CMOS inputs in parallel, then you have a much lower impedance from the driving circuit's point of view, which might require some added resistance. This would happen on the address lines for dynamic RAM chips (e.g. 16K x 1) where you might have 64 chips in parallel.