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TCAN4551-Q1: Maximum Data rate for TCAN455X-Q1

Ryuuichi machida
Guru 12665 points
Part Number: TCAN4551-Q1
Other Parts Discussed in Thread: TCAN4550-Q1, TCAN4550

Hello,

I would like you to confirm about following two.

Q1 Could you please tell me maximum data rate ?

According datasheet of TCAN4550-Q1(also 4551-Q1), there is following description.

1. TCAN4550-Q1 supports CAN FD data rates up to 8 Mbps it is recommended to use a 40MHz crystal

On the other hand, there is following description as well.

2. The recommended value for CLKIN or crystal is 40 MHz to meet CAN FD rates up to 5 Mbps data rates in order to support higher data throughout.

I'm confusing about which one is correct information.

Q2 If TCAN455X-Q1 support up to 8Mbps as data rate, which frequency should be used for OSC ?

("40MHz" is described for both 5Mbps and 8Mbps in current datasheet.)

Best Regards, 

  • 0
    TI__Guru 62920 points

    Hello,

    The device supports operation up to 8 Mbps. I understand the confusion about the reference to 5 Mbps - that is the maximum data rate defined in the ISO 11898-2 physical layer standard. For either rate, an oscillator frequency of 40 MHz is recommended in order to achieve enough time quanta per bit (minimizing quantization errors and allowing finer control over the sampling point configuration).

    Regards,

    Max

  • 0 in reply to Miguel Robertson
    Guru 12665 points

    Hello,

    >I understand the confusion about the reference to 5 Mbps - that is the maximum data rate defined in the ISO 11898-2 physical layer standard.

    Understood.

    Actually, according to ISO11898-2:2016 of "iso.org" , there are following description.

    • — Bit timing parameters for CAN FD for up to 2 Mbps have been defined (Table 13);
    • — Bit timing parameters for CAN FD for up to 5 Mbps have been defined (Table 14);

    What is 8Mbps targeted for ? (Next version of ISO11898-2 ?)

    Best Regards,

     

  • 0 in reply to Ryuuichi machida
    TI__Guru 62920 points

    Although 8 Mbps timing parameters are not standardized via ISO, the TCAN4550 supports toggling at this rate and so this higher speed of operation is made available to customers in case they have applications that require faster speeds and are OK with departing from the existing 11898-2 physical layer definition.  An example application could be flash programming of ECUs during manufacture.  Note that reliable operation at this speed requires that the loading presented by other nodes and interconnect cabling does not significantly distort the bit timing (that is, the maximum rate achievable is something that is determined at the whole network level rather than at one specific component).

    Max