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TXS02612: Access error to SD card

Jun Ishida
Expert 5640 points
Part Number: TXS02612

Hi team,

The customer observed access error to SD card when 1.2V/4ns noise has just come to DAT0B0. At the access error, DAT0A level was 3.3V in spite of being expected low level. We think the one-shot circuit inside works around Vcc/2 so the DAT0A should be still low level if the 1.2V noise is input to DAT0B0. Please see below screen-shot from the customer, and let us know the reason why the DAT0A is changed from low to high by just 1.2V noise?

Regards,

Jun

  • 0
    TI__Guru 61870 points
    Hi Jun,

    The 1.2V level is greater than the Vil level and hence cannot be considered low. Do you know why the input had the 1.2V signal and any way to avoid that?
    The one shot circuit we assume that the trigger point is around ~Vcc/2 but we cannot or it is not guaranteed on the datasheet.
    why is it not being seen on the other waveform?
  • 0 in reply to ShreyasRao
    TI__Expert 5640 points
    Hi Shreyas-san,

    Regarding the 1.2V input to DAT0B0, the voltage stays between VIL(max.0.15V) and Vcc/2(1.65V, threshold of one-shot operation). In that case, what is the correct output voltage for DAT0A? Do you think why the DAT0A output becomes 3.3V by the 1.2V noise signal?

    Please provide your thought/ comment to us as soon as possible?

    Reagards,
    Jun
  • 0 in reply to Jun Ishida
    TI__Expert 5640 points
    Hi Shreyas-san,

    And also, do you have any experiences of such a behavior that shows high level by the input voltage between VIL(max) and Vcc/2 in your customers?

    Regards,
    Jun
  • 0 in reply to Jun Ishida
    TI__Guru 61870 points
    Hi Jun-san,

    The 1.2V signal is not noise. Noise is in the uV or the mV level. Beyond the Vil level, the device cannot guarantee the low state anymore can the oneshot can trigger below Vcc/2. Would placing a series resistor on the input line help in reducing the unwanted glitch at the input?
  • 0 in reply to ShreyasRao
    TI__Expert 5640 points
    Hi Shreyas-san,

    Thank you for your comments. Please also let us know what the behavior of this device is if the input voltage is between VIL(max) and Vcc/2? And also, have you ever heard the same phenomenon from other customers in your experience?

    Regards,
    Jun
  • 0 in reply to Jun Ishida
    TI__Guru 61870 points
    Hi Jun,

    Behaviour is indeterminate between Vil and Vih levels.