+ Post New Thread
Results 1 to 3 of 3
  1. #1
    Junior Member level 2
    Points: 487, Level: 4

    Join Date
    Aug 2016
    Posts
    21
    Helped
    0 / 0
    Points
    487
    Level
    4

    RS485 Communication Level Converting

    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?

    •   AltAdvertisment

        
       

  2. #2
    Super Moderator
    Points: 65,915, Level: 62
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    13,408
    Helped
    3097 / 3097
    Points
    65,915
    Level
    62

    Re: RS485 Communication Level Converting

    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
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



    •   AltAdvertisment

        
       

  3. #3
    Super Moderator
    Points: 248,101, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    43,152
    Helped
    13128 / 13128
    Points
    248,101
    Level
    100

    Re: RS485 Communication Level Converting

    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.



--[[ ]]--