AM26LV32: Problem with detecting signal from AM26LV32EIDR

Anton Akolzin

Part Number: AM26LV32

Dear support,

When decoding a differential signal from a servo driver using the AM26LV32EIDR chip, false positives occur due to common mode interference on the lines, a cable 10 meters long.
Oscillograms of common mode signals on the differential lines and at the output of the microcircuit are applied. How to get rid of this problem?
Using matching resistors did not solve the problem.

over 6 years ago

0 Hao L over 6 years ago

TI__Mastermind 25705 points

Anton,

Can you check the differential voltage on the bus? It would be easier to see if the receiver responses to the input signal correctly. What cable do you use? Usually it's recommended to use twisted pair for RS-485 communication, which would cancel most of the differential noise.

Regards,
Hao

0 Anton Akolzin over 6 years ago in reply to Hao L

Prodigy 150 points

Hao,

I checked the differential signal on the signal bus, the interference level is ~ 2V, I think the problem is in grounding. Is there a document with recommendations for grounding devices? or how to properly make the ground on the circuit board of the device?

Regards,

Anton!

0 Hao L over 6 years ago in reply to Anton Akolzin

TI__Mastermind 25705 points

Anton,

You can check out this app note (session 11, Figure 9). Since the distance is not long, you could share the grounding on both ends.

Regards,

Hao

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AM26LV32: Problem with detecting signal from AM26LV32EIDR