PPK2 -> strange Source-mode current readings after sudden change in range

RE: PPK2 -> strange Source-mode current readings after sudden change in range

Sigurd Hellesvik — Tue, 25 Mar 2025 08:38:21 GMT

Alright, so i connected the LED on the 1k resistor instead.
And the button on the 100R:

The LED does not light now, as it is an 1k resistor, so too low voltage over the LED.
However, from the below graph, we can see that it consumes a bit of current when I plug in the LED:

No, this shows only ~1.5uA with 1k + LED only.

Then when I press the button to connet the 100R resistor, I get the following:

This jumps from ~1.5uA to ~35mA, which should be more than two "ranges" , right?

Here is also one test wiht 100,000 samples per second. I also put the supply voltage at the same that you got:

EDIT:
And for good measure, here is how the circuit looks:

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Mon, 24 Mar 2025 09:41:46 GMT

Hi Sigurd,

It is a bit hard to see, but it looks like in your setup the button turns the diode on or off. I observed the issue when the current went from "low" to "high" then back to "low". I would suggest changing the setup so that when the button is not pressed, the diode current is flowing through 1k resistance, and that the switch when pressed/on connects the 100Ohm in parallel with the 1k so the current increases significantly.

In my setup the "low current" was 2 "ranges" lower than the "high current" - not sure if the issue is also related to that, but ideally you would adapt Vout and/or R values so that the jump is (at least) 2 ranges.

RE: PPK2 -> strange Source-mode current readings after sudden change in range

Sigurd Hellesvik — Mon, 24 Mar 2025 09:18:19 GMT

Hi Kjell,

Sorry for missing your last query. I must have forgot to scroll beneath the other replies.

Anyhow: Nothing new from the devs. I will ping them.

For my part: Here is how I try to reproduce this:

And here is me pressing the button repeatedly:

In other words, I cannot reproduce the issue with this setup. Can you check if the setup looks correct, or if I missed anything?

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Fri, 21 Mar 2025 12:27:56 GMT

Hi Sigurd, have you had a chance to look at this? can you reproduce the issue we see?

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Mon, 27 Jan 2025 06:16:26 GMT

Hi Sigurd,

I hope Oslo survived the (multiple) snow/weather related incidents the past few weeks!

Do you have any updates you can share with me? Even if only that someone is investigating?

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Mon, 20 Jan 2025 10:23:55 GMT

Hi Kyrre,

I am not sure if the issue you see is related or not, but what I can say is that in my case, it never "recovers". In my case, the PPK2 starts bouncing between "range 0" and "range x" where x depends on the current level it gets confused on. On the diagnostic port I also see that it starts dropping a lot of samples, which can be observed in that the current trace/chart updates slower /erratically as samples are discarded.

RE: PPK2 -> strange Source-mode current readings after sudden change in range

Kyrre Aalerud — Thu, 16 Jan 2025 12:05:00 GMT

I have been confused by readings I get for a while now and when I found your post I think I am seeing this also.
I have a nRF53 running with BLE connected and it is supposed to be a quite steady draw. However I keep seeing very weird spikes. They come less frequently when I use less capacitance on the board input rail and they can change over time with no changes to load. What you write about auto-ranging may be relevant to this as it seems to happen when the steady state is close to next interval. Maybe the intervals need more leeway so they don't switch so easily? Or a way for user to lock the intervals to confirm if this is indeed an issue?

Here the issue just goes away after a bit (but it can also just appear).

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Mon, 06 Jan 2025 14:32:12 GMT

Same in Bergen - working home office today.

Do let me know if /when you are able to reproduce this please.

RE: PPK2 -> strange Source-mode current readings after sudden change in range

Sigurd Hellesvik — Mon, 06 Jan 2025 14:30:29 GMT

As you might have seen on the news, its a lot of snow here Oslo.
So I did not get to test today. However, I created a ticket to PPK2 devs either way, so they will get to it eventually.

I will let you know when I hear back from them

RE: PPK2 -> strange Source-mode current readings after sudden change in range

WhiteFang — Thu, 02 Jan 2025 06:23:04 GMT

Hi Sigurd,
That sounds very good, and a Happy New Year with best wishes for 2025 to us all!

As for me, I will test on a different PPK2 unit, probably tomorrow, to check that it behaves the same.

I have looked some more at it, but the below is pure speculation and mostly a summary of my opening post:

* "It" happens when abruptly changing current draw by more than one "range".

* after "It" happens, the range bits can often be seen fluctuating between 0 and the previous range (for me, typically 3 or 4).

* Once "It" happens, results are bogus until output is disabled or device is reset.

I did my testing with a simple red LED running at nominal 1.4mA and using a temporary 100Ohm resistor that I would temporarily put in parallel with R_LED to intermittently boost current to 10-12mA range and forcing an expected range change. "It" starts when removing the temporary resistor and the current is supposed to drop.

(I did not take additional screenshots.)

EDIT:

It was exactly the same behavior on a second PPK2 unit, so this should be easily reproduced across "any" device, most likely.

RE: PPK2 -> strange Source-mode current readings after sudden change in range

Sigurd Hellesvik — Fri, 27 Dec 2024 14:29:37 GMT

Hi,

Thank you for the thourogh testing and report on this!

Here is what I plan to do:

When I get back to the office 6th of January I will take out my PPK2 and test this (Might be later in that week depending on the my workload).

Then if I can reporduce this, I will create an internal bug report, and we'll have our PPK people look into this.

How does this sound to you?

Regards,
Sigurd Hellesvik