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SN65HVD07: rs485 full dublex tranceiver and 5V biss position encoder

denizdeniz
Prodigy 100 points
Part Number: SN65HVD07

1)      My encoder send differential data with 5 Volt to SN65HVD7X

2)      SN65HVD7X convert to differential data to single data also it decrease voltage to 3.3 V so that my controller are not damaged

3)      My microcontroller clock is 3.3 V go to SN65HVD7X (as single line)

4)      SN65HVD7X convert 3.3 V single clock (coming from microcontroller) to differential data but still 3.3 V NOT 5 Volt?

 My question is about (4. specification) Normally encoder MA+ and MA- should be work master CLOCK (5 Volt ) however it is 3.3 Volt

Can it be problem?

In other words, if I dont use level shifter (3.3 -5 V ) it is problem for my design?

Is there any chip used as both level shifter and tranciver?

  • 0
    TI__Guru 62920 points
    Hi Deniz,

    A level shifter should not be needed, since it is ok for 3.3-V-powered and 5-V-powered RS-485 transceivers to interface to one another. Both types of devices are designed to support the RS-485 signaling standard, which defines a required differential output amplitude, receiver input thresholds, etc.

    One thing to be careful of, though, would be pull up resistors on the bus. If there are pull ups populated on both sides of the link, you may get current flow from the higher voltage supply to the lower voltage one. If pull ups are used, it is generally best to just include them at one node.

    Regards,
    Max