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Isolating an RS-422 (RS-485 one way) network

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techie

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rs485 one way

I have an application where one-way data has to be transmited over wires at about 1Mbps to a distance of about 100meters. The cost of transceivers must be very low. I have successfully used simplex Rs-485 (Rs-422) except of one Problem. Sometimes, as the receiver and transmitters are powered bu different mains sources, the RS-485 drivers get blown up. I want to have some isolation in the circuit without increasing the cost too much.

Is it possible to use some pulse transformers with RS-422 like in Ethernet to isolate the transmitter and receiver circuits.
 

IanP

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pulse transformers rs422

With regards to the RS-485 isolated circuits I have very positive experience with 74OL6000 logic-to-logic optoisolators.
Put 485 IC on the isolated side and supply it of a dc/dc converter such as for example NMA0505S, or similar ..
Here you will find examples:
https://www.sipex.com/products/pdf/Isolated_RS485.pdf
Regards,
IanP
 

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I have tried it but I was wondering whether an ethernet type of transformer can be used in this application. It is cheap and gives a perfect protection. And there is no electronics exposed to the wiring.
 

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