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ADC08D500 / CalDly pin

K.Yaita
Guru 29720 points
Other Parts Discussed in Thread: ADC08D500

Hi Team,

Which timing of CalDly pin(127) latched that determine Calibration delay?
I believe it is latched at the power-up timing of ADC08D500 just one time .
Is my understanding correct?

Best Regards,
Yaita / Japan disty

  • 0
    TI__Genius 13335 points
    Yaita-san,
    The Calibration delay used to delay the calibration for power-on calibration only. It is meant to give time for the power supplies and other system variables to settle before performing a calibration. It is not used for on-command calibration.
    Regards,
    Luke LaPointe
    High Speed Data Converters
  • 0 in reply to Luke LaPointe
    Guru 29720 points

    Hi Luke-san,

    Thank you for your support.

    I believe the state of CalDly pin(127) is latched at the power-up timing just one time and internaly hold regardless of the state of PD pin.
    (I also believe it isn't latched at the negative edge of PD pin. )
    Is my understanding correct?

    I heard my customer has his system issue now, and he would like to know the function.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Genius 13335 points
    Kensuke-san,
    I'm investigating this question further for you. In the meantime can you elaborate on what issue the customer is seeing? What conditions are being used, etc.
    Thanks!
    Luke
  • 0 in reply to Luke LaPointe
    Guru 29720 points

    Luke-san,

    I appreciate for your support.
    I will ask more detail about the issue and inform to you when I get the update.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    TI__Genius 13335 points
    Kensuke-san,
    The CalDly pin is not "latched", therefore the recommended operation is to tie it high or low depending on the desired delay value. This can be as simple connecting to ground or the ADC supply so it remains at a constant value. If the PD pin is high upon power-up, the calibration delay counter will be disabled until the PD pin is brought low. Therefore, holding the PD pin high during power up will further delay the start of the power-up calibration cycle.
    Regards,
    Luke LaPointe
    High Speed Data Converters
  • 0 in reply to Luke LaPointe
    Guru 29720 points

    Hi Luke-san,

    I appreciate for your kind support.
    I will inform to my customer.

    Best Regards,
    Yaita

  • 0 in reply to K.Yaita
    Intellectual 910 points
    I do not use this adc08d500, but based on my understanding to adc08d1520rb, CalDly could be set and performs between powering up and calibrating. It means the latency caused by calibration is up to CalDly's setting. It helps to start calibrating after powering is stable. Thus, its setting depends on the setting of power on, or when PD goes low.