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question about unused pins of SN74LVTH574

TS Yang
Genius 4800 points
Other Parts Discussed in Thread: SN74LVTH574

Hi,

I'm using TI's SN74LVTH574, and connect unused input and output pins to ground.

However give signal to OE, SN74LVTH574 do not operate.

So let input to ground, and make output to floating, then operate normally.

when output is connected to GND, the power is switching as if the 3.3V is go through to ground.

I'd like to know the reason of this situation.

at SN74LVTH574 datasheet, there is explanation only for unused input pins.

And I can't find any comment for unused output pins.

  • 0
    Guru 316440 points
    Output pins always have a valid voltage level, either high or low.
    In your case, it's driven high, i.e., it is connected directly to Vcc.

    Unused output pins must be left open (which is not called "floating" because they don't float).