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BQ24780S: Data hold time

Shota Mago
Expert 8110 points
Part Number: BQ24780S

Hi team,

 

My customer has been using BQ24780S and he is asking about Data hold time specification of SMBus timing characteristics.

He uses MSP430F5310IRGCR as host controller and he says that hold time looks around 200ns(< 300ns: Data hold time specified in Table 6.6).

Does host controller need to satisfy tH(DATA) in table 6.6?

(Or does tH(DATA) mean that when BQ24780S sends something data, its data hold time takes at least 300ns?)

 

Best regards,

Shota Mago

  • 0
    TI__Genius 11850 points

    Hi Shota,

    A data hold time of 200 ns should be okay. The SMBus 3.0 spec (released in 2014) changed the minimum data hold time to 0 ns, and it is now the responsibility of the receiving device to add the necessary delay so that SDA does not change until SCL is already low. This is described in Section D.3 at the link below:

    http://smbus.org/specs/SMBus_3_0_20141220.pdf

    Having said that, please ask the customer to test their SMBus communication and make sure there are no issues. Just to be doubly sure, it would also be helpful if the customer could measure their SCL fall time. If the SCL fall time is <200 ns, then we can be very confident that the 200 ns data hold time will not cause any issues.

    Best regards,

    Angelo

  • 0 in reply to Angelo Zhang87
    TI__Expert 8110 points

    Hi Angelo,

    I understood.

    Thank you so much for your detailed answer.

    Best regards,

    Shota Mago