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AM26LV31E: Unexpected Output with A low, and Y going high

Daniel Mahoney
Prodigy 10 points
Part Number: AM26LV31E

Tool/software:

I am using an AM26LV31E.  Specifically AM26LV31EIRGYR.

I ground both G and G not.  Based on the datasheet truth table, When pin 12 (G not) is driven low, pin 4(G) becomes a don't care.  To me this configuration will keep the transmitter enabled at all times.  This is my baseline assumption.

If my assumptions are correct, I am seeing odd behavior.  My input to 1A (pin 1) is zero volts while my output on 1Y is high (Vcc level) and 1Z is low.  Based on table 7-1 of the datasheet, output Y should follow the state of input A.  Mine appears to be the complement 1Z output is 0 volts while 1Y is 3.3 volts when the input A = 0 volts.  

Could any provide their thoughts as to why I may be seeing this behavior?  Perhaps it is expected and I am misinterpreting the datasheet.

  • 0
    Guru 294220 points

    Yes; Y should be the non-inverting output.

    Do all four A inputs have a valid voltage? Does the output change when the input changes?

  • 0 in reply to Clemens Ladisch
    Prodigy 10 points

    Right now my input on all four A inputs is a pulled low (0V).  It is my interpretation that when A = 0, Y = 0

  • 0 in reply to Daniel Mahoney
    TI__Guru 62270 points

    Hi Daniel,

    Are you able to post a schematic? It may help to just double check that first.

    Daniel Mahoney said:
    Right now my input on all four A inputs is a pulled low (0V).  It is my interpretation that when A = 0, Y = 0

    I agree with you, The Y output should follow the A input since it's the non inverting output. Your interpretation of the datasheet seems to match what I would expect as well. 

    Can you also post a scopeshot of the A, Y and Z pins all in the same shot so we can do a quick sanity check?

    -Bobby