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

Daniel Mahoney

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.

1 month ago

0 Clemens Ladisch 1 month ago

Guru 273550 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 Daniel Mahoney 1 month ago 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 BOBBY 1 month ago in reply to Daniel Mahoney

TI__Guru 57230 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

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