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Mysterious power draw on ADXL362 200mSec after polling interrupt status?

Question asked by plalonde on Jun 4, 2015
Latest reply on Jun 18, 2015 by neilzhao

I'm using the ADXL362 in a power-sensitive system (wildlife transmitters, see holohil.com for the product line), and I have an un-accounted power draw about 200ms after reading the interrupt status; the power draw is not present if I remove the 362 from the system.

 

This draw is happening after the the system's microcontroller has been placed in the power-down sleep mode, waiting to be awaked by an attached RTC interrupt or ADXL362 activity/inactivity interrupt.

 

Is there an explanation for this draw?

 

The attached trace clearly shows the draw. In the LED case the first square step is the microcontroller wakeup, a sleep again, then a wakeup from either an RTC interrupt or from the ADXL interrupt, then dropping the microcontroller back power-down sleep. 200mSec later there a ramping draw peaks and falls off.   The same draw is visible in every system interaction that polls the 362 to check the interrupt status.  I have the 362 in its lower power mode, at lowest sampling frequency, in measurement mode.


Paul

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