AM26LV31: unusual outputs

Tom Thornton

Part Number: AM26LV31

Tool/software:

I have of two these drivers on the same board close together running at 3.3V. Inputs are 0/3.3 signals. The “Z” sides of the differential outputs when measured to GND show 3.3V signals but the “Y” sides all have 2Vdc, no matter what the input. This is the same for both chips and all 8 signals.

This is not the first build so this board has worked in other units, but the current location prevents me from checking the G and Gbar logic inputs. Is there a configuration of G/Gbar that would cause this or other configuration issues that might drive 2V on all the “Y” pins.

2 months ago

0 Clemens Ladisch 2 months ago

Guru 310880 points

Are you sure that this is not a '32 receiver? What is the exact marking? Did you acquire this from an authorized distributor?

0 BOBBY 2 months ago

TI__Guru 67260 points

Tom,

Do you have a schematic that I could review? As you pointed out, the Y pin should be an inverse relationship with Z. There shouldn't be a state where the Y pin latches to 2V.

Just to be sure, do you have a scopeshot of A, Z, and Y with the A pin having a sq wave being input into it?

Is this occuring on just one unit and have you done an A-B-A swap where you place this 'bad' unit on a known good board and also place a known good unit on the 'bad' board?

-Bobby

0 Tom Thornton 2 months ago in reply to BOBBY

Prodigy 10 points

Only on one assembly. 8 other assemblies that work fine. All in the same configuration, power and signals.

0 Tom Thornton 2 months ago in reply to Clemens Ladisch

Prodigy 10 points

thanks, location of parts are hidden by the chassis, but build photos do show the LV32. Many thanks.

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AM26LV31: unusual outputs