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Where does the current offset of my NRF52-DK comes from?

Hello,

I try to measure the current of the nRF SoC on my NRF52-DK, by using an oscilloscope and USB as a power supply, related to the guide from Nordic from here:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52832_dk%2FUG%2Fnrf52_DK%2Fintro.html

The following screenshot shows the voltage difference on the measurement resistor with the ratio 1V = 1 mA.

Where does the 1,4 mA current through the resistor comes from? The processor is placed in the shutdown mode, so the supply current of the processor should not be that high.

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  • Hi Daniel,

    Is this the guide https://infocenter.nordicsemi.com/topic/ug_nrf52832_dk/UG/nrf52_DK/hw_meas_oscilloscope.html?cp=4_2_4_5_6_1, you meant to link to?

    How did you initiate system of mode(shutdown mode) and are you sure it is in that state?

    Here is a link to the measuring current section, the following is noted about using the USB:


    Note: When measuring the current consumption:

    • Do not use the USB connector to power the DK during current measurements. Power the DK from a coin cell battery, or use an external power supply on the External Supply connector P21.
    • The current measurements will become unreliable when a serial terminal is connected to the Virtual COM port.
    • After programming the nRF52832 device, the USB must be disconnected and the development kit power cycled to reset the debugger chip before current measurement.


    Can you try again with a different power source and see if the results persist?

    Regards,
    Jonathan

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  • Hi Daniel,

    Is this the guide https://infocenter.nordicsemi.com/topic/ug_nrf52832_dk/UG/nrf52_DK/hw_meas_oscilloscope.html?cp=4_2_4_5_6_1, you meant to link to?

    How did you initiate system of mode(shutdown mode) and are you sure it is in that state?

    Here is a link to the measuring current section, the following is noted about using the USB:


    Note: When measuring the current consumption:

    • Do not use the USB connector to power the DK during current measurements. Power the DK from a coin cell battery, or use an external power supply on the External Supply connector P21.
    • The current measurements will become unreliable when a serial terminal is connected to the Virtual COM port.
    • After programming the nRF52832 device, the USB must be disconnected and the development kit power cycled to reset the debugger chip before current measurement.


    Can you try again with a different power source and see if the results persist?

    Regards,
    Jonathan

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