Power Profiler Kit II measurement error

[MartinZ]

I made some tests with PPK-II in source meter mode by connecting a load resistor in series with a Fluke 8846A ampere meter to the PPK output. A also hooked a GW Instek GDM-8351 voltmeter in parallel to the PPK output.

Here are the results:

The PPK is out of spec around 500uA. From time to time, while changing the output voltage up and down, those red values suddenly got much better, in accordance with the +/-10% specified max. error. But I couldn't figure out what exactly makes the PPK suddenly jump in/out of spec. However, most of the time I observed the large errors from the table above.

Given the described behavior, I suspect a FW error in range changing logic. Are you aware of this? Can this be fixed in a future FW upgrade?

[Audun]

Hi,

> Before trying the new FW, I'd like to know how to safely revert back to official FW after this test.

After installing the new firmware, the Power Profiler app will complain that you are using the wrong version. You can click "No" to ignore this and keep using the new firmware. If you click "Yes", Power Profiler will install the official firmware again, matching that particular version of Power Profiler. So yes, you can safely revert back

> The problematic behaviour is thus at the lower end of the 500uA-5mA range, and it doesn't seem to be caused by the offset dictated by POT 3 (TP21).

This was what I observed also, which made me wonder if it was a calibration error that could be corrected with some gain. But as you point out, only the lower end is problematic, so a different curve might have to be applied here. I have not yet investigated if the calibration data with generate during PPK2 production is sufficient. This is the kind of improvement I can't provide a timeline for.

I can create a local version of Power Profiler that applies a curve that improves my particular PPK2 in this range, and we can see if it makes an improvement for you. If this looks like a viable approach we can try to assign resources to more thoroughly test this.

Thanks for checking the shell metrics by the way. The low number of "samples dropped" indicates it is likely not an issue with the FW detecting the wrong measurement range.

Best regards,

Audun