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Bias register value of ADM2582E

Question asked by sofy Employee on Feb 1, 2013
Latest reply on Feb 25, 2013 by hmarais

Hi, I have a question about Bias register value of ADM2582E.

ADM2582E usage as below,

RS485 half duplex, p to p ,10Mbps,

Vcc=5V

Cable length 1m-2m,

Rt 120 ohm

 

When both of  R1 and R2 is 990 ohm (following with formula in page 12 of AN-960),  about 10% rate incidence, start bit and 1st data are missed in data stream after ADM2582E in receiver side. (note: we confirmed before ADM2582E in receiver side, there is no missing data with probing points quite near by ADM2582E.)

But when both of R1 and R2 is 4.7k ohm, there are no missing data at all.

Also remove both of R1 and R2, there are no missing data at all.

 

Is there any missed points or misunderstanding that I should check?

I would like to make clear how to get bias register value.

 

Thanks.

Tatsuya

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