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SN65HVD72: SN65HVD72

Ian Wang
Mastermind 29700 points
Part Number: SN65HVD72
Other Parts Discussed in Thread: THVD1410

Hi Sir,

Pls advise if SN65HVD72 VCC=3.3V  ， RS485 of motor controller VCC=5V; if it will work fine?

Thanks, Ian. 

  • 0
    TI__Guru 62920 points

    Hi Ian,

    Yes, this is no problem - with either supply voltage the device will still meet all the interface requirements of the RS-485 standard.  The only potential concern would be if failsafe biasing using external pull-up resistors on the "A" line is implemented on both sides.  In that case there could be current flow from the larger supply to the smaller one through the external resistances.  The solution would be to not use pull-ups on both sides or to place a diode in series with the lower-voltage pull-up. (SN65HVD72 features internal failsafe functionality so no pull-up resistances are needed, anyway.)

    Please let us know if you have any further questions on this.

    By the way, for a newer design I would recommend the newer THVD1410 device instead.  It is p2p with SN65HVD72 but improves upon VCC range, common mode noise immunity, and ESD immunity.

    Max