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RS485 with 3.3V microcontroller

Azeem Awan
Prodigy 90 points
Other Parts Discussed in Thread: SN65HVD72, SN65HVD82

I need an RS485 transceiver with rate upto 120kbps(min) that can be interfaced with 3.3V microcontroller and should have low power.
I am considering SN65HVD72 but can someone tell me its output voltage levels?

because i need RS485 between 3.3V controller and a 5V device.

tell me if any level shifter is needed?

  • 0
    TI__Guru 62920 points
    Hi Azeem,

    The receiver output (interface to MCU) of SN65HVD72 will range from 0 V (ground) to VCC. The exact minimum and maximum limits (assuming an 8-mA load) are defined in the device's datasheet as the "VOH" and "VOL" parameters (see page 6 of the current datasheet).

    If the rest of your system (MCU, etc.) is powered via 5 V, you could also choose to use a 5-V-powered RS-485 transceiver as well. SN65HVD82 would be a good example. Both 5-V and 3.3-V transceivers are designed to be compliant to the RS-485 interface standard, and so they are fully inter-operable with one another. They only differ in supply voltage and the voltages used for the single-ended I/O pins (D, R, DE, and RE), which scale with supply voltage.

    Max