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TCAN1051-Q1: Can i get a CAN repeater without mcu?

Part Number: TCAN1051-Q1
Other Parts Discussed in Thread: TCAN1051, SN74LVC2G14, SN74LVC2G132

Hi,

Can i get a CAN repeater without any MCU or CPU? Use two TCAN1051 and some logics?

  • Hi Kevin,

    We have an Isolated CAN FD Repeater Reference Design that you may be able to modify to accomplish what you need. The arbitration logic can be found in Figure 2. 

    Let me know if you have any questions about this document. 

    Regards,
    Eric

  • Hi Eric,

    This is great!  It`s really helpful!

    But i have a problem about the Delay line. To achieve the delay line function, i need use the circuit in Figure4 to  replace  the U8 and U11 in Figure2, Is it right?

    And how to understand the time delay unit is asymmetric? Because the c1 charge through R1 and discharge through the bus?

    Regards,

    Kevin

  • Hi Kevin,

    To achieve the delay line function, i need use the circuit in Figure4 to  replace  the U8 and U11 in Figure2, Is it right?
    No, the delay of U8 and U11 can be done simply with a buffer or other method. 

    And how to understand the time delay unit is asymmetric? 
    The Asymmetry refers to the delay difference when transitioning from dominant-to-recessive vs recessive-to-dominant. The circuitry in Figure 2 will introduce a delay to the signal during a dominant-to-recessive transition, but no delay during a recessive-to-dominant transition. This behavior is modeled by the simulation of Figure 4. The circuitry in Figure 4 is not needed for implementation and is included to illustrate one of the effects this repeater method will have on the system. \

    Let me know if this makes sense.

    Regards,
    Eric

  • Hi Eric,

    If  the circuitry in Figure 4 is not needed for implementation and is included to illustrate one of the effects this repeater method will have on the system.

    Why the schematics has this circuit in Figure4?

    Regards,

    Kevin

  • Hi Kevin,

    Appologies, I don't believe I was clear in my previous response.The schematic for TIDA-01487 illustrates one method of the arbitration logic circuitry that is used in its own design. For the delay element of this circuity, the circuit shown in Figure 4 of the reference design is used. This series of components is used because the values of the R and C component can be selected to control the delay time as well as its asymmetric delay characteristics (see previous reply for description). If desired, another delay method such as a self-contained buffer could also be used in place of this circuit to achieve the same  behavior - so this circuit is not required for use in the reference design. Because we have conducted testing and have hardware associated with the design above, we recommend this configuration (using Figure 4) as a solution.

    Let me know if this clarifies my previous reply.

    Regards,
    Eric

  • Hi Eric,

    Thanks for you reply!

    Can i replace the SN74LVC2G132 with SN74LVC2G14?And i can change the RC value to get the same delay time.

    Regards,

    Kevin

  • Hi Kevin,

    Based on what I know about these devices, this should be fine. Note that you will see a difference in propagation delay not only in the differing switching characteristics, but also due to varying hysteresis / threshold values and pin input capacitance. If you plan to tune this timing of the RC (maybe with a variable resistor) or your system allows for a greater timing variance, these may be of minimal concern. 

    Regards,
    Eric