SN74LXC2T45-Q1: The impact of floating input pin of SN74LXC2T45-Q1

user4637774

Part Number: SN74LXC2T45-Q1

Tool/software:

When the SN74LXC2T45-Q1 chip is in use, if the input pins are left floating, what kind of impacts might this bring about?

0 Clemens Ladisch 5 months ago

Guru 317450 points

Increased power consumption, and the outputs can be high or low or oscillating; in the worst case, damage. See [FAQ] How does a slow or floating input affect a CMOS device?

The internal pull-down resistors are not always active; see section 8.3.1.1 of the datasheet.

0 Joshua Salinas 5 months ago

Hello,

I would look at the FAQ Clemens shared. Gives you a good overview why we should not leave CMOS inputs floating.

Regards,

Josh

0 user4637774 5 months ago in reply to Joshua Salinas

If the input pins are floating, can it be regarded as a direct short circuit between the power supply and the ground?

+1 Clemens Ladisch 5 months ago in reply to user4637774

Guru 317450 points

No; the two input transistors are only partially open. The shoot-through current could be about 25 mA per pin, depending on the actual input voltage.

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