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TCAN4550: HOT swap application for TCAN4550

Antony Fu
Expert 3345 points
Part Number: TCAN4550

Hello,

We are promoting TCAN4550 in one server project, and customer need to support hot-swap, but it looks like this part can't support, so would you like to help us double confirm it? if not, so whether we have hot-swap device for the CAN port?

Thanks,

Antony

  • 0
    TI__Guru 62920 points

    Hi Antony,

    The CANH/CANL lines are high impedance when the device is not fully powered and are designed to power up without creating glitches on the bus.  This is typically what is needed for a transceiver to be used in hot swap applications.  Was there another feature you were looking for?

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    TI__Expert 3345 points

    HI  Max,

    Thanks, there is no other feature to look for.

    And we just completed the schematic, and would you like to help us double review it?

    R288 and  R289 are 60.4 ohm 1/2w resistor.

    Thanks,

    Antony

  • 0 in reply to Antony Fu
    TI__Mastermind 29370 points

    Hi Antony,

    I have reviewed your schematic and have the following comments. Overall it looks good.

    The WAKE pin does not appear to have any form of driving stimulus that would be used to create a state transition to trigger a wake up event. It appears that the design will not use this feature. If so, you can tie the WAKE pin directly to VSUP or to GND and eliminate the 33k, 3k, and 0.01uF resistors and capacitors.

    The GPO2 pin is an open drain architecture and will require a pullup resistor to VIO (3.3V).

    Due to the resolution of the schematic picture, it is hard for me to tell the reference designator and value for certain. But the capacitor in the CAN split termination looks to be C55 or C56 and has a value of 4.7uF. Typically I see and use 4.7nF due to the frequency response and 4.7uF may be a little too large for this application and may need to be adjusted to better filter out the common mode noise that is usually of a higher frequency component an requires a smaller capacitor.

    I will note that the NWKRQ pin defaults to a driven output pin referenced to an internal 3.6V rail. If the MCU cannot tolerate a 3.6V signal level, this pin can be configured for an open drain architecture that would require a pullup resistor to VIO (3.3V). You will want to confirm you can tolerate the 3.6V level, or add an option for a pullup resistor.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Expert 3345 points

    HI Jonathan

    Since SPI has four modes as below, so which modes are acceptable for TCAN4550? And the BMC chip of customer only support mode0 and mode 2.

     

    Mode 0 CPOL=0, CPHA=0 
    Mode 1 CPOL=0, CPHA=1
    Mode 2 CPOL=1, CPHA=0 
    Mode 3 CPOL=1, CPHA=1

    Customer needs to communicate with the PSU through the CAN port, so whether this need some special sequence for SPI, CAN and PSU?

     

    Thanks and Best Regards,  

    Antony Fu 

  • 0 in reply to Antony Fu
    TI__Guru 62920 points

    Hi Antony,

    TCAN4550-Q1 is designed to support Mode 0 (CPOL = 0, CPHA = 0).

    Regards,
    Max