• State Resolved
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 31 subscribers
  • Views 114 views
  • Users 0 members are here
Support feedback
Options
Options
Related

PCM5101A: XSMT signal timing

Danilo A.
Mastermind 30020 points
Part Number: PCM5101A


Hi Team,

Posting on behalf of the Sumitomo Wiring Systems Ltd.

Please tell about the XSMT timing for PCM5101A.

On the data sheet it says “XSMT tr and tf times of less than 20nsec.”  
Additionally, in my understanding, the data sheet also seems to say,
“SCK can be max at 50MHz (20nsec minimum) thus the rise and fall time for XSMT should be within this cycle.”

When using only 3 signal lines (No SCK using for I2S), is XSMT limited to under 20nsec?
Additionally when SCK is not used, could you please tell me what happens if XSMT goes over 20nsec?

Regards,

Danilo

  • 0
    TI__Mastermind 31561 points

    Hi Danilo,

     The reason behind this limitation  is not explicitly in the datasheet of this mature part, but  max speed of sck (50MHz) gives you a Cycle time of 20ns so that was the idea behind the tr/tf min for XMST.

    In the absence of SCK, I believe the 20ns constraint on tr/tf will not be there anymore. The purpose of soft mute mainly is to mute the part before and disruption in supplies or clks. 

    So even if the mentioned 20ns tr/tf is violated and XMST is not activated fast enough, only a pop may happen. No functionality issue would be there.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Mastermind 30020 points

    Hi Arash,

    Thank you for your response.

    Regards,

    Danilo

  • 0 in reply to Arash Loloee
    Prodigy 20 points

    Thank you for your response, Arash-san.

    In the data sheet, there is the following statement; "If XSMT is moved from "1" to "0" in 20 ns or less, then the device will interpret it as a digital controlled request to mute. It will perform a soft mute, then move to standby." 

    Conversely, when XSMT is moved from "0" to "1" in 20 ns or less without SCK what will happen? Similarly what will happen if more than 20 ns?

    Thank you in advance.

    Regards,

    Tatsuo OGUCHI @ Sumitomo Wiring Systems, Ltd.

  • 0 in reply to Tatsuo Oguchi
    TI__Mastermind 31561 points

    Hello Tatsuo-San.

    Once the XSMT is activated or deactivated, it will trigger a soft ( gradual) muting or unmuting. 

     As I mentioned in the above post,  without SCK  I don't think it should be a problem even if tr/tf   of  XSMT is more than 20ns . For tr and tf of less than 20ns it is no problem with or without SCK.

    kind regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 20 points

    Dear Arash-san,

    Thank you for your response.
    Could you please let me check just in case.

    My understandings are;
    "Soft mute or analog mute thresholds do not work for tr."
    "Or these thresholds is operating inside the IC, but not shown in the operation."

    Are these correct?

    Thank you in advance.

    Regards,

    Tatsuo OGUCHI @ Sumitomo Wiring Systems, Ltd.

  • 0 in reply to Tatsuo Oguchi
    TI__Mastermind 31561 points

    Hello Tatsuo-San,

    The 20ns threshold will not effect or show in operation.

    Kind Regards,

    Arash