[ABANDONED] Ozone strange power consumption measurment with JLink Ultra+

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  • [ABANDONED] Ozone strange power consumption measurment with JLink Ultra+

    Hello,

    I'm currently trying to use Ozone with a JLink Ultra+ to measure the power consumption of an embedded project and I'm facing strange behaviour.

    The first issue I encountered was that the displayed consumption changes a lot when I change the Ozone's sampling frequency. As you can see on the first attached image, for the same code (BLE advertising and blinking LED), the measures seems drastically different and I don't really know what setting to believe to have the more representative values.
    The second issue I faced was that when the LED is ON, I expected a higher static current consumption and what I get is some small spikes as shown on the second attached image (LED is ON 2s every 5s).

    Is there any configuration I missed or are those normal trace to get using the JLink Utltra+ ?

    Thank you
    Images

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    • Screenshot from 2023-03-20 17-41-49.png

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  • Hello,

    Thank you for your inquiry.
    Such an issue is not known to us.

    Could you provide your J-Link serial number for reference? You can find it at the bottom starting with with S/N.

    Are you powering your board/chip only via the debug interface or are you also powering via some external power source?

    Best regards,
    Nino
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Hello,

    Thank you for your answer.
    Our J-Link serial number is 504501744.

    We are indeed powering our board only through the debug interface.
    To add a bit more information, there is a buck regulator on the board that generate the needed 3.3V. Do you think that this regulator (TPS630250RNCT) could inject some noise on the supply and that we would better use a LDO for this specific test ?
    Also the used LED is an RGB one controlled using PWMs but all 3 duty cycles were set to 100% for testing.

    Best regards,
    Benjamin

  • Hello Benjamin,

    Thank you for the additional details.
    A buck converter is usually famous for ripple/noise due to its switching design. So an LDO is generally recommended instead for embedded designs where applicable.
    Here is a nice article I found in this topic:
    resources.altium.com/p/using-l…tching-regulator-your-pcb

    But before you go and redesign your board I recommend to hook up an oscilloscope and see how the signal looks in circuit. Do you see the same pattern there as well?
    I recommend to use an active probe to make sure the impedance of the probe head is not damping away the ripples.

    If you see the same pattern on the scope then this is simply how the power delivery on your board looks like.
    One cause could be the buck converter as explained above or it could also be the USB Power supply to the J-Link. Here you could try to use a different USB Hub or similar that is externally powered, just to make sure that the J-Link is not already being fed an "unclean" power input.

    Best regards,
    Nino
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.