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Question about inverter like SN74LVC1G04

frederic douit
Intellectual 480 points
Other Parts Discussed in Thread: SN74LVC1G04, SN74LVC1G06, SN74LV1T04

Hello,


I am wondering if this part could work for my purpose.

I need to put a High or Low signal to a chip input(A). For that, I will use the output pin of an other chip(B).

But, this output(B) is a pulling low. I need that when it's pull low, my other input(A) chip get a High.

So I though to use an inverter. I though to put supply at the input of the inverter, and his output to the input chip(A).

I put the output chip (B) between supply and the input of the inverter.

With output(B) floating, the input(A) should get a Low signal?

When output(B) pulls low, input(A) should get a High signal?

Here a quick schematic:


Do you think it can work?

And I guess I have to use the same voltage for the inverter than the chip A input VCC (5V)?

Thank you for your help

  • 0
    TI__Guru 61870 points
    Hi Frederic ,

    Yes , the SN74LVC1G04 is single gate inverter in logic family .It has best current drive and wide operating voltage range among the logics .
    Please note that it is not bidirectional , so A to B and B to A cannot work .
    If you have a floating input , you need to have a pullup or pull down to keep the inputs at known state , so that you have desired output .
    You could also consider open drain sn74LVC1G06 , which would require a output pull up to go high .
  • 0 in reply to ShreyasRao
    TI__Guru 61870 points
    The Vcc for the system at 5V would be ideal . If either of the devices operate at different voltages , you would require level translation devices . In that case , you can use SN74LV1T04 which will be inverter /translator .
    In your case , the input needs a pullup resistor to Vcc to have output of the inverter low signal whenever the B is floating .
  • 0 in reply to ShreyasRao
    Intellectual 480 points

    Hi Shreyas,

    Thank you for your answer.

    Just to be sure,

    My chip B pull low is an open drain, so I guess it's not really floating but maybe High-Z. So do I still need a pull up resistor?

    And I guess the inverter has to take his own supply to put his output High? So I have to homogenize all supply? 5V for his supply and input, and 5V for his output and chip A input?

    Is the chip A has to have 5V supply to get his input as High with the incoming 5V?

    thank you for your help