SN65HVD1781-Q1 RS485 LOAD TERMINATION

Srinivasan Elumalai

Dear Team, I have query related to the RS485 termination. Our requirement is transceiver should detect the signal when the loop total termination is minimum value of 40 ohm. But in the datasheet mentioned 54 to 60 ohm. is transceiver will support 40 ohm loop termination value? or is need any additional circuit needed to support 40 ohm minimum loop resistance

over 4 years ago

0 Hao L over 4 years ago

TI__Mastermind 25705 points

Srinivasan,

The RS-485 transceivers can work with different terminations. That being said, however since 40Ohm load is stronger than 54/60Ohm, the diver output voltage might not reach the same level as the specification in the data sheet. This should not be an issue on a carefully designed system.

Regards,

0 Srinivasan Elumalai over 4 years ago in reply to Hao L

Prodigy 60 points

Hello Mr Hao L,

Thank you for feedback ,

We required 3 node termination points i,e total loop termination will be 40ohm. is any appplication note ,design guideline will more helpfull to me, for design a reliable system

Thanks and regards

Srinivasan Elumalai

0 Hao L over 4 years ago in reply to Srinivasan Elumalai

TI__Mastermind 25705 points

Srinivasan,

Out of these 3 nodes, two farthest ends should be terminated properly, while the 3rd node is considered as a stub. You can refer to this app note (section 6 on page 3) for detailed discussion about termination, stub length, etc.

www.ti.com/.../slla272c.pdf

Please let me know if you have more questions.

Regards,

Hao

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SN65HVD1781-Q1 RS485 LOAD TERMINATION