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DP83867E: Question for hardware design

Guru 16770 points
Part Number: DP83867E


Hi

We have questions for the design data using DP83867E.

1.
Do you have recommendation for the crystal about the following parameters?
We will select a crystal based on paraemters including the following specs and Table 105 of datasheet.

- Crystal Series Resistance (typ)
- Total period Jitter (Peak to Peak)

2.
Could you tell us absolute maximum ratings (min/max) at XI?

3.
As for each pin's function, can you provide interal PU and PD resistor values?

BestRegards

  • Hi,

    1. What crystal are you planning to use? Do you have a datasheet to share?
    2. What absolute max rating at XI? What parameter are you referring to here?
    3. The internal PU/PD are 9k ohm.

    Kind regards,
    Ross
  • Hi Ross

    Thank you for your reply.

    >1. What crystal are you planning to use? Do you have a datasheet to share?

    There is no plan yet what kind of crystal to be used.

    Our customer is about to choose crystal based on parameters not only table 105 but also crystal series resistance and total period jitters.

    If you have recommendation, we want to inform it to the customer.

    >2. What absolute max rating at XI? What parameter are you referring to here?

    Sorry for confusing you.

    XI I meant is the clock in.  We want to know the absolute maximum rating of the min/max voltage to XI pin.

    >3. The internal PU/PD are 9k ohm.

    Thank you.  I understood all PU/PD resister has 9kohm value.

    BestRegards

  • Hi nana,

    We recommend the ESR of the crystal is below 50-60 ohms. It is also recommended that the crystal has a drive level over 100uW if possible. Total period jitter of a crystal is not expected to be an issue.

    Please see the DP83867E EVM for an example crystal circuit to use.

    The XI pin, if driven by an external oscillator, should be 1.8 Vpk-pk. Above that voltage will overdrive the buffer and cause the buffer to age quicker than expected.

    Best Regards,