nRF6707 Incorrect current measurement

[Florian Flex]

Hello,

I'm trying to make some current measurement using the nRF6707 and a nRF5 SDK Board(10040) (Board out of the box, shunts untouched). 

We're facing problems measuring the current consumption. Indeed, the current consumption is negative and centered around 31µA (See attached screenshots showing the phase when DUT is set to ON). Playing around with the switching points or the voltage regulator didn't changed anything.

Setup:

-My firmware (iBeacon sample code) is running OK regarding to the blinking LED on the nRF5 SDK board

-All 3 switches of the nRF6707 are set on "DK"

-Obviously the nRF6707 is stacked on the nRF5 SDK board

-The nRF5 SDK board is powered by the micro USB cable (power switch ON)

-The J-Link is connected on Debug in of the PPK (flashed with ppk_110.hex)

-The power profiler App starts correctly 

What did we do wrong ?

Thanks in advance,

Florian

[Mttrinh]

Hi,

Have you cut the SB9 track shorting solder bridge on your DK? If not, can you try this and see if it solves the issue.

Take a look at the Quick start guide.

[Florian Flex]

Hi,

I didn't. I realize that reading the documentation the first time I've focused on the "shorting" word..... Fast reading. Thanks for the info !

Thanks a lot !

[Florian Flex]

Trying now to mesure the current consumption of the DK(PCA10040) board running the ble_app_beacon code example, the measured values doesn't match the expectations we can observe using the following tool:

https://devzone.nordicsemi.com/power/      @ 3V, 500ms, 20 bytes, -16dbm

 (iBeacon sample code with LED_NUMBER=0 and  BUTTON_NUMBER=0, and TX POWER set to -16dbm)

The PPK measures a AVG current of 505µA while the simulation on https://devzone.nordicsemi.com/power/  AVG current of 23µA. What is the reason ?

Also, are you able to explain me in what the measured parameters such a the "Charge' is useful ? The user guide doesn't say much about its meaning. Thanks in advance 

[Mttrinh]

Hi,

I suspect it might be that you have logging on. Can you check if NRF_LOG_ENABLED is enabled in sdk_config.h?

"Charge" is current * time(µC = µA * s). So charge is basically total current over a given time. If you know the charge in for example, a BLE event, you can se 20use it to calculate the average current over different intervalls. Let's say that a BLE event use 20µC and an intervall 100ms, then we have:

20µC / 100ms = 200µA average current over 100ms.

[Florian Flex]

Thanks for this usefull answer.