• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 21 subscribers
  • Views 210 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMK05028: Exceeding max INx frequency

David Huang
Intellectual 2285 points
Part Number: LMK05028
Other Parts Discussed in Thread: LMK5B33216, LMK5C33216

Hi team,

My team is current using LMK05028 with INx frequency 388.8MHz, which is smaller than the maximum INx frequency rating.

However, it appears that due to the customer's FPGA issue, sometimes FPGA output frequency goes to 777.6MHz, which is 2 times higher than their current frequency, and exceeded the max INx frequency rating.

 

The maximum INx rating on the datasheet is 750MHz, using 777.6MHz surpass the maximum rating by 27.6MHz. Is this over frequency also supported as a part of the margin, or will it cause any issue or malfunction to the device?

Regards

  • 0
    TI__Intellectual 2285 points

    Hi team,

    Could someone please address on this?

    Regards

  • 0 in reply to David Huang
    TI__Mastermind 28550 points

    Hello David,

    I don't expect a problem, in fact it may very well work just fine/within marge - but that operation cannot be assured.

    The issues here are:

    1. Input sensitivity, can the divider/input operate with such a high frequency and provide a valid input to the next stage of circuitry.
    2. Input validation detection, can the device determine the input is valid with such a high frequency.

    Exceeding either of these should not cause an issue or malfunction once the output frequency returns to valid input range based on the configuration of the device.  For example, the input validation circuitry is configured for a specific frequency during the configuration of the device using the TICS Pro GUI.

    73,
    Timothy

  • 0 in reply to Timothy T
    TI__Intellectual 2285 points

    Hi Timothy,

    Thanks for the response!

    Timothy T said:
    For example, the input validation circuitry is configured for a specific frequency during the configuration of the device using the TICS Pro GUI.

    Adding a question here, if the customer goes with 777MHz as input frequency, do they need to add additional settings(e.g. write on other registers) after TICS Pro GUI? It seems like TICS Pro GUI only allows input to be lower than 750MHz.

    If such setting is require, could you also advise the details on how should the customer perform this setting?

    Regards,

  • 0 in reply to David Huang
    TI__Mastermind 28550 points

    Hi David,

    It originally sounded like the question was, "is it acceptable to expose the part to the higher frequency?"  Sounds like you want to use the higher frequency?

    Might I suggest the LMK5B33216 or LMK5C33216?  This is specified to 800 MHz.

    73,
    Timothy

  • 0 in reply to Timothy T
    TI__Intellectual 2285 points

    Hi Timothy,

    Apologies if it was a bit confusing.

    Timothy T said:
    It originally sounded like the question was, "is it acceptable to expose the part to the higher frequency?"  Sounds like you want to use the higher frequency?

    Your understanding is correct, I believe the customer wants to ensure the device functions normally at 777.6MHz input frequency. Just double checked your response I assume the device wouldn't work if the input freq stays at 777.6MHz without falling back to below 750MHz?

    The customer has been evaluating this device for quite some time so I think it would be the best if we can make it work with 777.6MHz without changing the part number, is this possible?

    Regards,

  • 0 in reply to David Huang
    TI__Mastermind 28550 points

    Hi David,

    I currently don't have a timeline to see if we could approve for the higher frequency.

    73,
    Timothy