We would like to add pull-up and pull-down resisters as attached figure to increase the noise margin.
Is it possible to connect it to RS-485 5V bus?Because Visoout is 3.3V.
Thank you for post. Based on the product and question, you might have better access to appropriate support in this forum (as opposed to the Inertial MEMS forum). Good luck with this project!
Hi Nishimiya,The AN-960 application note pages 6 and 7 provides a description for adding bus biasing resistors to increase the noise margin: (see http://www.analog.com/static/imported-files/application_notes/AN-960.pdf)
If the customer uses 1.2kΩ pull-up and pull-down resistors, and uses 120Ω termination, this will result in a 157mV offset, which will mean an increased noise margin.
Yes, it is possible to connect the ADM2582E to a 5V bus with the 1.2kΩ pull-up and pull-down biasing resistors.
Thank you very much for your reply.
What is the supported sink current of Visoout pin?
The ADM2582E Visoout pin was not designed for external connections.The ADM2582E Visoout pin was designed for external connection to the Visoin pin only, to power the RS-485 transceiver portion of the circuit. I don't have an estimate of the possible sink current capability of the Visoout pin.
However, talking to the designer of this part previously, it is possible to connect a 1.2kΩ pull-up resistor to the Visoout pin.
I understand. Thank you.
I have one more question.Does a 1.2kΩ pull-up resister support −9 V to +14 V of the receiver Input Voltage in the absolute maximum ratings?
Yes you can operate the ADM2582E over the receiver input common mode range (−7 V < VCM < +12 V) with the 1.2kΩ pull-up resistor.
The absolute maximum ratings for the ADM2582E data sheet state:
Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product.
So, the ADM2582E cannot operate on a continuous basis at −9 V to +14 V.
Thank you very much for your support,
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