Power profiler kit higher current with a custom hardware

[olibro]

Hi,

i'm developing an application with the NRF51822 device using the NRF51 development kit (DK). I bought a power profiler kit (PPK) to measure current for advertising and connection phases. When i measure current for the DK connected to the PPK, as showed in figure 9 in the PPK Manual, i get the expected current of around 4 uA between advertising and connection events.

When i connect a second DK with the same software as external device, as showed in figure 11, i get around 16 uA between events. I measure the same current when I use an external power supply (figure 12).

When i connect a multimeter in series to measure current between advertising events i measure 4 uA. Therefore i think that something is wrong with the configuration for external devices. I have prepared the DKs correctly (cut SB9)

Did i do something wrong or misunderstood the manual?

Edit: I've read in the NRF51 DK user guide, that the Interface cpu is powered when an external power supply is used. Then it draws around 20 uA. Is there an Option to power only the NRF51422 on the NRF51 DK?

Thank you in advice

Oliver

[MartinBL]

Hi,

Please refer to the DK User Guide v1.2 Chapter 6.3:

Important: When USB is not powered, the Interface MCU is in dormant state and will draw an additional current of ~ 20 μA in order to maintain the reset button functionality. This will affect board current consumption, but not the nRF52832 current measurements, as described in the Measuring current on page 20 section

In other words, if you power the kit through the External Supply header (P21) and measure the current flowing into this, then the MCU will add an additional ~20uA to your measurement. Measurements across SB9 will not include the current flowing to the MCU.

Here is a workaround: How to power the NRF52 chip as standalone (without the DK)?

[olibro]

Thank you for the link. That's exactly what I needed to get this thing working.