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DP83TG720S-Q1: power up timing

Chuqiang Wen
Expert 5010 points
Part Number: DP83TG720S-Q1

Hi Expert,

Here are questions about DP83TG720S and DP83TC812S power-up stabilization.

As specified in datasheet,  720S needs MIN. 65ms stabilization time and 812s needs MIN. 10ms.

Questions: 

1, Does that mean software need wait such a long time to start register access after chip is powered on? Especially for 720s, it is more than 65ms?

2, In customer design, there is a 10ms delay time from power-on stability to RESET release, how much waiting time is needed after RESET release and before registers can be accessed? Take 720s as example. 

720s:

812s:

Thanks!

Ethan Wen

  • 0
    TI__Intellectual 2260 points

    Ethan,

    The specification listed indicates the minimum time before accessing the PHY register; Therefore, the actual specification number is higher for DP83TC812S and DP83TG720S.

    Sincerely,
    Jason Lee

  • 0 in reply to James Lee
    TI__Expert 5010 points

    Hi Jason,

    It is not very clear for me. Please help confirm. 

    Chuqiang Wen said:
    1, Does that mean software need wait such a long time to start register access after chip is powered on? Especially for 720s, it is more than 65ms?

    From your description, the answer for this question should be yes. Correct? 

    Chuqiang Wen said:
    2, In customer design, there is a 10ms delay time from power-on stability to RESET release, how much waiting time is needed after RESET release and before registers can be accessed? Take 720s as example. 

    It should be refer to the RESET Timing T6.2, correct? 

    Thanks! 

    Ethan Wen

  • +1 in reply to Chuqiang Wen
    TI__Intellectual 2260 points

    Ethan,

    Regarding your first question, yes.

    For your second question, since power-on takes priority over reset, 65ms is still required.

    Sincerely,

    Jason Lee