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THVD1500: THVD1500

jayashree
Intellectual 680 points
Part Number: THVD1500
Other Parts Discussed in Thread: TCAN1044-Q1, TCAN1042-Q1

Hi Team,

In my requirement we need to short CAN and RS485 signals in a single line.

Can we connect (CAN_H & RS485_D+) in one line and (CAN_L & RS485_D-) in another line directly?

The details and the high level block diagram of our requirement is attached for your reference.

Please go through it and suggest us CAN, RS485 transceivers that has enable or control which an make the output signal to tristate/ high impedance state so that only one interface will be connecting at a time.

With regards,

Jayashree.CAN & RS485 TI query.pptx

  • 0
    Guru 316420 points

    If possible, power down the unused transceiver. The TCAN1044-Q1 datasheet says: "Optimized behavior when unpowered", "Bus and logic pins are high impedance (no load to operating bus or application)"; the THVD1500 datasheet says "Glitch-Free Power-Up/Down for Hot Plug-in Capability" which probably means the same.

    If you cannot switch the power supply, you have to disable at least the driver. On the THVD1500, pull the driver enable (DE) pin low; on the TCAN1044-Q1, pull the standby (STB) pin high. Please note that the devices are not entirely passive and still weakly bias the bus.

    Many other CAN and RS-485 transceivers have the same features.

  • 0 in reply to Clemens Ladisch
    Intellectual 680 points

    Hi,

    Thanks for the reply.

    Above you mentioned is for interfacing between processor and transceivers, like the same way on bus end (CAN_H, CAN_L, RS485_D+, RS495_D-) side should we consider any protections.

    The voltage level of CAN bus will be referred to VCC supply (mostly 5V will be given). What will be the voltage level of RS485 at bus end (RS485_D+, RS485_D-)?

    With regards,

    Jayashree.

  • 0 in reply to jayashree
    TI__Mastermind 25705 points

    Jayashree,

    Please refer to Vo(dom) and Vo(rec) for the signal level of CAN bus (section 6.8 on TCAN1042-Q1 datasheet), and Vod and Voc for the signal level of RS485 (section 6.6 on THVD1500 datasheet). BTW, both devices works with -7V to 12V common mode voltage.

    Regards,

    Hao