74HC14 Schmitt Trigger

[AmandaM]

Hello Again

Very quick question this time. Should I tie the unused inputs of the 74HC14 Schmitt Trigger to ground or are they ok left floating?

Many thanks

 

[(*steve*)]

Tie them to ground, Vcc, or any other source of a valid logic level. The first two are preferable, but the third can be an option if routing is an issue.

 

[HellasTechn]

With digital electronic chips it is better if you ground the unused inputs. Left floating may be ok or may produce errors

 

[AmandaM]

Thanks all, as usual, it's appreciated. I will tie them to ground—I assume that they will not need a pull-down resistor?

Thanks...

 

[poor mystic]

No pull down is needed. Just straight to ground.

 

[kpatz]

If it's a production circuit that is stable (not undergoing revisions), you could tie the unused inputs directly to ground. But if it's a prototype, using a resistor (or a jumper) makes it possible to remove it if you need to use one of the unused gates in the future, instead of having to cut traces on a PCB.

 

[HellasTechn]

That is a good idea.

 

[Colin Mitchell]

Generally, with a Schmitt Trigger, it does not matter if the inputs are left floating because the hysteresis is about 30% of supply and gates will not self-oscillate. Tieing them HIGH or LOW does not affect the quiescent consumption.

 

[AmandaM]

Thanks everyone—your help and comments are appreciated.