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SN74AUP1G126: Input high while everything else low

Brian Antheunisse
Expert 5305 points
Part Number: SN74AUP1G126

Hi guys,

Question from a customer:

The data sheet states OE pin disables the input pin of the buffer.  I have a question based on the statement of the input being disabled when OE pin =GND.

If VCC pin = 0V, Gnd pin=0V, OE pin=0V, input pin=3.3V, will it damage the buffer IC?

 

I’m looking at using this in a battery powered device, there are cases that last for about 1-2 sec when the buffer VCC=0V, Gnd=0V, OE=0V, and Input=~3V.  After the 1-2seconds the buffer will have VCC=3.3V, OE=3.3V, GND=0V, input=~3V.

If the input is actually disabled with OE pin, then applying a voltage to the input won’t damage or latch up the part.

Thanks,

Brian 

  • 0
    TI__Guru* 97046 points

    Hi Brian,

    When Vcc = 0V, all pins of the device are placed into a high-impedance state. This is defined by the "Ioff" spec in the electrical characteristics table. Ioff circuitry is what makes it safe to apply 3.3V to the input (or output) when Vcc = 0V.

    The input disable feature is only active when Vcc is within the operating voltage range -- it is intended to prevent excessive current due to floating inputs when the input is unused.