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TCAN1042H: Driver/Receiver Switching Characteristics maximum values

F.N
Expert 8760 points
Part Number: TCAN1042H

Hi team,

My customer wants to know the Driver/Receiver Switching Characteristics(*1) maximum values.
Only the typ values are described in the data sheet.

 *1) Driver:   tpHR,tpLD,tsk(p),tR,tF
     Receiver: tpRH,tpDL,tR,tF

Please let me know.

Best regards,
Fumio Nakano

  • 0
    TI__Guru 74252 points

    Nakano-san,

    For CAN device, the total loop delay is typically the more useful parameter when designing a system, since loop delay is ultimately what limits bus length and amount of CAN nodes and passive devices on the bus. Total loop delay is listed in the datasheet and has minimum, maximum, and typical values, and includes the delay contributed by tpHR, tpLD, tpRH, tpDL and rise and fall times.

    That being said, I was able to locate characterization data for the TCAN1042 that give maximum value measurements for these parameters.

    Driver

    Maximum
    tpHR 82.0ns
    tpLD 58.4ns
    tsk(p) 24.69ns
    tR 50.1ns
    tF 54.18ns

    Receiver

     

    Maximum
    tpRH 70.2ns
    tpDL 70.5ns
    tR 12.0ns
    tF 11.15ns

    For the maximum values, these are typically seen at higher temperatures. For nominal temperatures, the data skews towards the typical value seen in the datasheet.

    Please let me know if you have any other questions or concerns.

    Regards,

  • 0 in reply to Eric Hackett
    TI__Expert 8760 points

    Hi Eric-san,

    Thank you for your prompt reply.

    I understood you don't have measured maximum values.
    Please let me know below.

    ① Calculation process of each value.

    ② The definition of tsk(p) is |tpHR-tpLD|.
         Calculating from this definition, tsk(p) becomes 23.6ns (= 82.0ns-58.4ns).
        But, the suggested value is 24.69ns.
        What is the difference?

    ③ Since the ratio between the typical value and the max value of the total loop delay is about 1.6,
        if this value is uniformly multiplied to the typical value of each switching characteristic,
        the below value is obtained as the max value.

        As an estimate, is this understanding wrong?

       Driver
                      MAX　　　 　TYP
        tpHR     120 ns        75 ns
        tpLD      88 ns         55 ns
       TSK(p)   32 ns         20 ns
        tR          72 ns         45 ns
        tF          72 ns         72 ns

       Receiver
                      MAX        TYP
        tpRH    104 ns       65 ns
        tpDL     80 ns        50 ns
        tR         16 ns        10 ns
        tF         16 ns        10 ns

    Best regards,
    Fumio Nakano

  • 0 in reply to F.N
    TI__Guru 74252 points

    Nakano-san,

    1. These values were taken from an ATE parameter characterization matrix that was logged when this device was being developed. Measurements were taken across 40 units and at -55C, 25C, and 125C. In this matrix, an average of the  minimum, maximum, and typical values across the units are given with σ, +/-3σ, and +/-6σ given as well. 
    2. That formula is true if measuring the parameters for one unit. Because these parameters are averages across 40 units, the value from the table I shared may be slightly off from the formula.
    3. Did you get the 1.6 multiplier from a source? If you or the customer is just trying to get a rough estimate for some system design decision, this is okay, but ultimately it will be best to know what your system parameters are with all parts integrated (transceiver, passives, controller, cabling, etc.). This will be crucial for software to time messages and sampling correctly.

    Please let me know if you have any other questions or concerns.

    Regards,

  • 0 in reply to Eric Hackett
    TI__Expert 8760 points
    Eric-san,

    Thank you for your cooperation.
    Your answer is very helpful.
    Thank you!!

    Best regards,
    Fumio Nakano