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LMX2595: LMX2595 SYNC Pulse Width

Kei Yamamoto
Prodigy 10 points

Part Number: LMX2595

I'm looking at the LMX2595 datasheet, SNAS736C – June 2017 – Revised April 2019.             

Question 1:

I've read the explanation in "7.3.11.1 General Concepts" in the datasheet, and I understand that

t1 and t2 indicate the time when synchronization begins,

but this statement does not specify the SYNC pulse width, right?

(Someone in our company claims that this indicates the pulse width of the SYNC signal, and I would like to show him the manufacturer's response that it does not indicate the pulse width.)

Question 2:

I know that the SYNC timing requirements are specified in 6.6 Timing Requirements.

The setup and hold relative to OSCin are specified.

Since Category 3 requires synchronization to OSCin, I thought it would be fine to follow these timing requirements,

but what about Category 2, which does not require synchronization to OSCin?

I don't think the setup and hold are specified, but I would like to know the specifications for the initial pulse width.

 

Thank you.

  • 0
    TI__Guru** 115360 points

    Hi Yamamoto-san,

    Here is the timing diagram.

    Only Cat.3 sync has restrictions and timing requirement on the SYNC pulse. 

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,

    Thank you very much for your reply.

    I understand what you are saying.
    However, what I want to know is the timing in the case of Category 2.

    I also know that it is not written in the datasheet.
    I know something that says "SYNC Timing NOT Critical In category 2 "

    However, as long as there is a rising edge, does it matter how narrow the pulse width?
    I think it is strange that pulse width is not specified as a requirement for use in Category 2.

    And I'm also waiting for the answer to question 1 too.

    Thank you.

    Kei

  • 0 in reply to Kei Yamamoto
    TI__Guru** 115360 points

    Hi Yamamoto-san,

    The sync pulse width is not matter in Cat.2 sync, the device only needs the rising edge of the sync pulse. 

    Pulse width of the sync signal has no relationship with the time (t1 and t2) taken to complete the synchronization.

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi, Noel.

    So it doesn't matter how short the pulse width is.

    And thank you for your answer to question 1. I'm grateful for such a comment. I agree.

    Your advice helped me.

    Thany you.