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SN65HVD1050: SN65HVD1050

Ben Mignano
Prodigy 10 points
Part Number: SN65HVD1050
Other Parts Discussed in Thread: TMUX7309F, TMUX7308F, TMUX7462F

Hello,
I would like to know if there is an analog switch that can be used to MUX/DEMUX a CAN bus and maintaining compliance with CAN Bus standards. I am using two channels SN65HVD1050 CAN TX/RX devices and I would like to loopback them via analog switches, in order to test their integrity. The analog switches (single DPDT) should not affect the normal operation and the system must maintain CAN Bus compliance. The voltage is 5V and the data rate would be up to 1Mb/s. The new device will be attached between the transceiver terminals and the external connector. I would like to know if I can preserve the electrical characteristics of the SN65HVD1050 device as well noted in its datasheet.

  • 0
    TI__Guru 74322 points

    Ben,

    I'm going to bring in a representative from our Mux team within Interface to this conversation, but can you elaborate a bit on which signals you're switching? I assume you mean the CANH and CANL signals? And another point I want to make is that CAN transceivers have loopback within the transceiver, but my guess is that you want to check the loop back without affecting the main bus.

    So you want to have a mux/switch that switches the CANH and CANL signal from the main bus to a position back to itself to make sure the signal is okay, then be able to switch back to the main CAN bus. Is that right?

    Regards,

    Eric Hackett 

  • 0
    Prodigy 10 points

    Hello Eric,

    Yes, I would like to connect two transceivers CANH and CANL signals together and disconnect them from the connectors; CAN1H to CAN2H and CAN1L to CAN2L. The two transceivers do not share the same bus. There are two distinct CAN bus lines and each channel is attached to one of them. The external analog SPDT switches will disconnect them from the connectors  and connect the two CAN channels together for a loopback test.

    Best regards,

    Ben Mignano 

  • 0
    TI__Intellectual 2694 points

    HI Ben,

    Our Analog switches support way higher bandwidth/data rate than required for CAN and should not impact the bus standard as these are passive switches.

    We will have a cross team discussion between the Switch and CAN team to align on the best solution, understand the risks if any, considering the switch will be used on the bus side that can potentially see higher voltages due to fault scenarios arising on the CAN bus.

    Bryan from my team will get back to you with additional questions that might come from the discussions. 

    Thank you,


    Regards,

    Sandesh

  • 0 in reply to Sandesh Rawool
    Prodigy 10 points

    Hello Sandesh,

    Thank you for your message. Yes, the problem is not related to the bandwidth of the analog switches but to the ESD protection and high voltage specifications of the CAN bus. In other words, the analog switch should have the same front-end  and power cycling circuit of the  SN65HVD1050.

    Thank you very much, and I'm eager to receive your feedback.

    Regards,

    Ben Mignano 

  • +1 in reply to Ben Mignano
    TI__Genius 10974 points

    Hi Ben,

    Can you help specify the high voltage you are trying to protect against? We offer fault protected muxes, however, they require a minimum of an 8V supply but can protect up to a 60V fault. The device I would recommend if you can meet those requirements is the TMUX7309F. This can be configured as a 2:1 (SPDT) multiplexer, just probably has more channels than you need (you can just tie them to GND or leave them floating). Essentially, the fault protection is triggered when the input to the mux exceeds the supply rail of the mux by the datasheet specified threshold voltage (VT, usually around 0.7V). When this happens, the multiplexer will pull the output to the supply that was exceeded and keep it there until the fault is cleared.

    Let me know if you can help clarify the exact conditions you are expecting to see on the bus and what supplies you have available and we can better help develop a solution here if the above one is not feasible.

    Thanks!

    Bryan

  • 0 in reply to Bryan Marshall
    Prodigy 10 points

    Hello Bryan,

    Thank you for your quick response. The TMUX7309F might be a good candidate for this job. The VDD-VSS supplies are not an issue.

    Ideally, the application would require a quad SPDT analog switch and all the CAN inputs protection, circuit capabilities of the SN65HVD1050 and most importantly all the CAN bus certifications (i.e., SAE J2284 High-Speed CAN Bus for Automotive, SAE J1939 Standard Data Bus Interface, ISO 11783 Standard Data Bus Interface, NMEA 2000 Standard Data Bus Interface). 

    When does this device go in full production?  

    Regards,

    Ben Mignano

  • 0 in reply to Ben Mignano
    TI__Genius 10974 points

    Hi Ben,

    Thanks for clarifying these requirements.

    This device is still in preview unfortunately and cannot give a set production date. Other fault protection muxes that you can currently order samples/devices for are the TMUX7308F and the TMUX7462F devices, though they have a different configuration (8:1x1 and 1:1x4 channel muxes).

    Thanks!

    Bryan