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74HC14 Schmitt Trigger

AmandaM

May 15, 2015
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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*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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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

Apr 14, 2013
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With digital electronic chips it is better if you ground the unused inputs. Left floating may be ok or may produce errors
 

AmandaM

May 15, 2015
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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...
 

kpatz

Feb 24, 2014
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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.
 

Colin Mitchell

Aug 31, 2014
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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

May 15, 2015
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Thanks everyone—your help and comments are appreciated.
 
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