• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 18 subscribers
  • Views 591 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.

TXS4558 Dual SIM Mux - Why use ClockRun ?

Mark Major
Prodigy 55 points
Other Parts Discussed in Thread: TXS4558

The ClkRun pins allows the clock signal to be transmitted to the SIM when the SIM is deselected.  When would that be useful?

  • 0
    TI__Expert 6335 points

    Mark,

    My understanding is that the purpose of CLKRUNx is for ensuring compatibility with SIM cards that do not support 'Clock Stop'.

    Let's take the ISO/IEC 7816-3 standard, which specifies the electrical interface and transmission protocol for these cards.

    There is a power saving feature in that specification which is called 'Clock Stop'. This feature allows an interface device to stop transmission of CLK to a SIM card, when data is not expected from that SIM card.
     
    'Clock Stop' is an optional feature for a SIM card. SIM cards that do not support 'Clock Stop' will require continuous reception of CLK. Therefore, the TXS4558 CLKRUN pin must be configured high when connected to a 'Non Clock Stop' SIM card.

    Best Regards,
    Nirav

  • 0 in reply to Nirav Patel
    Prodigy 55 points
    Thanks, Nirav!

    I have the spec, and think I understand now. The TXS4558 is able to switch between the two SIMs without powering them down. So if it is deselected but still powered up, then it would be beneficial to stop the clock because that would reduce its power draw, if the SIM supports that feature.
  • 0 in reply to Mark Major
    TI__Expert 6335 points
    Mark,

    Yes that is correct. If you have any further questions, please let me know. Thank you.

    Regards,
    Nirav