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ADS1015-Q1: Alert timing after across the threshold

Chul Kim
Intellectual 260 points
Part Number: ADS1015-Q1

We want to walk the ADC thread and fire off an alert.
I want to know how long it will be before the input signal goes over the threshold and an alert goes out.

  • 0
    TI__Guru** 113765 points

    Hi Chul Kim,

    The ALERT is not triggered by comparing the input voltage but rather by comparing the conversion result to the threshold level.  So for the ALERT to trigger the ADC must be converting.  This works best when operating in continuous conversion mode as opposed to single-shot mode.

    To be more clear, only the mux input selected can trigger an ALERT.  Other inputs that may exceed the threshold will not trigger an ALERT until they are selected for conversion.  As to the timing of the trigger, this will depend on the data rate selected and the COMP_QUE bit settings selected in the configuration register.  The COMP_QUE bit settings are for triggering an ALERT if the threshold is crossed for durations:

    • After 1 conversion
    • After 2 conversions
    • After 4 conversions

    The fastest data rate is 3300sps (there is an error in the current datasheet which shows 860 as the fastest) which is 303us.  So the fastest the ALERT can trigger is 303us, or it can be delayed by 2 or 4 times that value.  So the time it will take to trigger an ALERT will depend on the configuration settings being used.

    Best regards,

    Bob B