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SN65HVD3088E: Digital Signal Input Level

Peiheng Liu
Prodigy 620 points
Part Number: SN65HVD3088E
Other Parts Discussed in Thread: THVD1500, THVD1450

Hi,

I am looking into the datasheet of SN65HVD3088E and it specifies VIH from 2V to Vcc, which also applies to TI newer RS-485 trx devices like THVD1500. Could I tell that this transceiver could be used with a 3.3V MCU without any level shift in the digital interface?

Best Regards,

PH

  • 0
    TI__Guru 53555 points

    Hi Peiheng,

    Yes, these inputs of SN65HVD3088E are designed to be compatible with 3.3V MCUs in this way. Please make sure that the MCU in your design can provide these pins' necessary input current defined in sections 6.5 and 6.6: Electrical Characteristics. 

    Regards,

    Eric

  • 0 in reply to Eric Schott1
    TI__Guru 62920 points

    PH,

    Also please note that the R pin output level will scale with VCC, so you should ensure that the 3.3-V MCU is capable of tolerating a 5-V input.  If not, you may want to use a diode in series with the R output to block the high level along with a pull-up resistance (to 3.3 V) at the MCU input pin.  Alternatively, you may want to instead simply use a transceiver that is powered via 3.3 V directly such as THVD1450.

    Regards,
    Max

  • 0
    TI__Prodigy 620 points

    Eric, Max,

    Thanks for your inputs! These are very helpful.

    Best Regards,

    PH