4000 CMOS supply and input voltage

I believe they can run from 3 volts to 15 volts supply.
but, what about the input voltages?

I'm using 8 volts as my inputs, but are you supposed to use 5volts for all logic inputs.

thanks [/b]

 

Your logical low will be the Vss voltage (usually found on pin 7 of a 14-pin chip and the logical high will be the Vdd voltage (usually found on pin 14 of a 14-pin chip). My memory is too poor to remember the threshold voltage that differentiates a high from a low .... the average of Vss and Vdd? Can't remember. But don't allow your lows and highs to run outside the boundries of Vss and Vdd. Yes, there are protection diodes that are supposed to stop any damage, but they have their limits and exceeding those voltage at a minimum will slow down the logic.

Dean

__________________
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

 

thanks Dean

 

The threshold is nominally 50% of supply rails, but spec allows 30% to 70%.