System OFF mode but with 150ms consistent shoot seen in oscilloscope

[kathleenlai]

Hi Team,

I would like to know what does the system do after I call system off function as per below:

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void PowerApp__EnterSleepMode(void)

{

ret_code_t err_code;

// Go to system-off mode (this function will not return; wakeup will cause a reset).

err_code = sd_power_system_off();

APP_ERROR_CHECK(err_code);

return;

}

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

void PowerApp__EnterSleepMode(void)
{
    ret_code_t err_code;

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
    return;
}

I have check through the oscilloscope to check how's the system react when system off mode.

I have a consistent pulse with Interval is now 150ms - 155 ms , the current peak is at 2.2mA. 

Is that normal? or Can anyone explain to me what will happen right after sleep when I connect NRF52840 to oscilloscope.

Im using SDK  16.0.0.

Thank you.