How to read Power Profiler Kit Measurements

[peter237]

Hi,

I have a beacon that uses 4 AA batteries, each has 1.5V and 2600 mAh. When connecting the board to the PPK I get the attached measurements when doing a lot of scanning and advertising:

It is weird that I seem to have a continuous consumption of 0.8 mAh. Could I have done anything wrong? I set the switches to DUT Select: DK, Power select: Reg. It is still connected to a nRF51DK from which I supply the USB power.

Now if I do the calculation of having 6V input from the batteries, the nRF is driven with 3.3V so I have a little less than double the capacity, e.g. ~4700 mAh @ 3.3V. Which average should I take, is it the RMS or the AVG? This is very important as they show very different results. So can I say that it will run about 1300 hours or is it more like 2300 hours?

Thank you

[Hung Bui]

Hi Peter,

Could you show us how you connect your DUT to the Power profiling kit and the power source for it ? Are you using the DK for testing ? If now why did you set DUT Select to DK ?

Constant 0.8mA could be due to the HFCLK running. Have you tried a simple example for example CPU sleep most of the time and only wake up for RTC event ? Just to make sure you can see constant low current when the CPU sleeping ?

Note that you should only supply maximum 3.6 V to the external supply port or 5.5V to USB supply.

[peter237]

Sorry, I used the "DUT select: External" of course.

The HFCLK is not running, I tested the same code on the DK and on the external board. I tested a simple Advertising Example as well and with that board, there is a constant draw of 0.8mA. Maybe there is something wrong with the DC/DC converter, I have to check that. Do you have a sample PCB layout for a Beacon with 4AA batteries?

Could you help me with the RMS / AVG question as well?

Thanks

[Hung Bui]

Have you tried with very simple code ? Just simply put the CPU to sleep , to see if the PPK can measure current correctly ? Regarding AVG and RMS if you are looking for the average current consumption, you should use AVG. I heard from the developer, RMS is provided to measure noise characteristic.