The current peak of 334uA during system on Low power mode

[Surya]

I observed a peak of 334 ua during system-on low-power mode during idle time which is periodic around 4 sec. I am using ble with RC clock option.

1.is it waking for calibration of the clock source?

2.how much current will be drawn for calibration of the clock?

3.how to stop calibration for a time period where ble is not used?

[Simonr]

Hi

The RC oscillator calibration can be adjusted by tweaking the calibration timer interval and calibration timer interval under constant temperature (NRF_SDH_CLOCK_LF_RC_CTIV and NRF_SDH_CLOCK_LF_RC_TEMP_CTIV in sdk_config.h). The SoftDevice should only wake up when it needs to calibrate the LFRC clock, but keep in mind that setting higher values than the recommended 16 and 2 (at least every 8 seconds within temperatures of 0.5°C and every 4 seconds if the temperature is changing) will most likely cause the oscillator to drift. Not calibrating the LFRC will likely lead to inaccurate timers in the low power mode for instance.

When the SoftDevice wakes up, the current peak will increase quite a bit, but the average current consumption during sleep when using the LFRC should not be much more than ~0.4µA according to the Electrical specification in the PS (see ION_RAMOFF_RTC versus ION_RAMOFF_RTC_LFXO for instance).

Best regards,

Simon

[Surya]

I am getting a current of an average of 1.9 uA to 2.1 uA with a peak of 334uA (a periodical of 4 sec).

before going to idle state by calling Pwr_mgmt_run() function, I am stopping the BLE stack, but still, the peak is coming.