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TPS53667: Minimum supported clock frequency of PMBus of TPS53667

Shunsuke Yamamoto
Expert 7701 points
Part Number: TPS53667

Tool/software:

Hi team.

I have several questions regarding PMBus specification. TPS53667 is daisy-chained with PMBus and I2C in my customer's usecase.

1. is it possible to do daisy chain with PMBus and I2C on same bus(data line and clock line)?

2. I2C may operate at a clock frequency of 10kHz, so my customer would like to confirm whether PMBus of tps53667 works with a clock frequency of 10kHz. PMBus specification attached on this thread states that it can support a clock frequency from 10kHz, so we believe that TPS53667 can support the same.

3. If not, what is the minimum clock frequency of PMBus that TPS53667 uses to communicate?

 smbus20.pdf

Best regards,

Shunsuke Yamamoto

  • 0
    TI__Intellectual 2150 points

    Hi Shunsuke,

    1. is it possible to do daisy chain with PMBus and I2C on same bus(data line and clock line)?

    - This should be possible as long as the driver is capable of supporting the various transaction types. Block read, byte write etc...

    3. If not, what is the minimum clock frequency of PMBus that TPS53667 uses to communicate?

    - The lowest that has been tested with the TPS53667 is 100kHz. As long as the timeout isn't hit (50ms I believe), there shouldn't be a problem operating at 10kHz but it has not been validated with this device. 

    Best Regards,

    Nash

  • 0 in reply to Nash Boyd
    TI__Expert 7701 points

    Hi Nash-san,

    Thank you for the answer. I don't understand the timeout you mentioned. What is timeout of PMBus? Could you please kindly explain?

    Nash Boyd said:
    As long as the timeout isn't hit (50ms I believe), there shouldn't be a problem operating at 10kHz

    Best regards,

    Shunsuke Yamamoto

  • 0 in reply to Shunsuke Yamamoto
    TI__Intellectual 2150 points

    Hi Shunsuke,

    The TPS53667 has a 50ms clock timeout. If the device is not receiving data from the PMBus transaction before the 50ms timeout, the 53667 will reset its communication and again wait for its own address. This can be caused if other devices on the line are clock stretching or holding the data line down. 

    Best Regards,

    Nash

  • 0 in reply to Nash Boyd
    TI__Expert 7701 points

    Hi Nash-san,

    Thank you for the answer. I understood what the timeout is, and we evaluate 100kHz clock frequency of PMBus and 400kHz clock frequency of PMBus.

    My customer would like to know the variance of the clock frequency of PMBus of 100kHz and 400kHz. Are there any variances?

    100kHz PMBus clock frequency min/max or +/-?%

    400kHz PMBus clock frequency  min/max or +/-?%

    Best regards,

    Shunsuke Yamamoto

  • +1 in reply to Shunsuke Yamamoto
    TI__Intellectual 2150 points

    Hi Shunsuke,

    You would have to verify in the PMBus spec what they allow in regards to tolerance.

    Best regards,

    Nash