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THVD1520: 3.3V & 5V Mix application

Brian Wang0928
Genius 15030 points

Part Number: THVD1520
Other Parts Discussed in Thread: THVD1420

Hello team,

 

Customer would like to double confirm if below circuitry is able to apply for THVD1520. 

3.3V is for MCU F28377 bias power.

5V is for the RS485 bias power

as we understanding, there is a pull-up resistor 5MOhm connected to 5V inside the RS485 at D and /RE pin. Is there a concern when 3.3V level from MCU?  

image.png

 

Regards

Brian

 

 

 

  • 0
    TI__Mastermind 24932 points

    Hi Brian,

    Yes, the only concern is that the R output could violate the MCU voltage rating. It will be around 4.7V. 

    The other D, DE, /RE pins will not be an issue. 

    However, there is an easier solution that I would recommend. Consider switching to the THVD1420. This transceiver can be supplied with either 3.3V or 5V on VCC. If it is supplied with 3.3V, then the R pin will no longer be an issue. 

    Best,

    Ethan