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RS485 Communication Level Converting

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H2M

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Hi
I want to use MAX485 in my board. Can i connect MAX485 Vcc pins to 12 volt and then connect RO,DI, RE and DE pins directly to my STM32 microcontroller that have 3.3v logic level?
 

Hi,

Do it like every other person needs to do it: look into the datasheet.

I doubt the MAX485 is specified to operate on 12V ... to know it for sure I also needed to read the datasheet.

I doubt it because RS485 signals don't go up to 12V. Usually the signals go up to 5V, but there are RS485 drivers supplied with 3.3V.
This is what I'd use.
Now I don't know the part numbers. I had to look at distributors and/or at semiconductor manufacturers. They usually have interactive selection guides to find the suitable part.
The same can you do.
Often there are a lot of results. Then use the one with best availability, highest stock count, lowest price...or the one you already have seen in other projects.

Klaus
 

There are no commonly available RS485 drivers working with a supply voltage higher than 5V. They would need to drop the voltage with an internal regulator.

Usual solution is an external 5V regulator. Depending on the required output current (is RS485 terminated?), a switch mode buck converter is advisable.
 

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