nPM2100 : stabilisation of the current consumption when the output power is low

RE: nPM2100 : stabilisation of the current consumption when the output power is low

Menon — Thu, 18 Sep 2025 13:15:56 GMT

Good to hear that.

RE: nPM2100 : stabilisation of the current consumption when the output power is low

SCF — Thu, 18 Sep 2025 13:00:00 GMT

Dear Nordic team,

You were wright: I need to place some pull down resistors when the device is turned OFF at the output of our sensor.

Now, when I turn all the system OFF the current consumption is around 3µA under a VBAT of 3V. This is a good result.

Be carefull to not check those little currents only with the PPK2. I need to use an ammeter (µA range) with the PPK2 to obtain correct values. I also use the terminal to not discard any samples.

Thank you Nordic for your help!

RE: nPM2100 : stabilisation of the current consumption when the output power is low

Tomi Koskela — Fri, 12 Sep 2025 11:54:05 GMT

Hello,

Have you tried powering the instrument without nPM2100 if you get the same behavior? Anyway it sounds like something is consuming current at the instrument side and nPM2100 is just supplying it. It can be for example I2C lines/pull-ups.

RE: nPM2100 : stabilisation of the current consumption when the output power is low

SCF — Thu, 11 Sep 2025 14:51:25 GMT

Hello Audun,

I checked with the EK:

1) PPK2 is giving the voltage to the EK.
2) The EK is supplying the instrument.
3) The instrument is placed in the OFF mode.
4) The current suppying the instrument (EK V_OUT) go to 1uA and rises directly to more than 200uA and after 3 minutes it stabilises to around 10 uA.

I let you check with the schematics if you see something wrong.

I can also tell you that when I put the nPM2100 in the ship mode, the current goes directy to 65nA with no delay.

Thank you Nordic

RE: nPM2100 : stabilisation of the current consumption when the output power is low

Hung Bui — Thu, 11 Sep 2025 08:30:09 GMT

@audun: The schematic is shared in 351155 https://devzone.nordicsemi.com/support-private/support/351155
Let me know if you can't access.

RE: nPM2100 : stabilisation of the current consumption when the output power is low

Audun — Thu, 11 Sep 2025 07:02:42 GMT

No problem, SCF,

I am sadly not able to recreate the issue on an nPM2100-EK using 10 uF VINT either..

I think next step would be a design review via private techsupport to look for potential culprits.

As a side note, have you tried already or are you able to connect your load to an nPM2100 EK to verify if you see the same behavior there?

Best regards,

Audun

RE: nPM2100 : stabilisation of the current consumption when the output power is low

SCF — Wed, 10 Sep 2025 09:15:32 GMT

Dear Audun,

Thank you for your answer.

Ok great. Auto mode selection is nice when having V_BAT > V_OUT.
No need to use the registers (for the moment).

Yes, the measurments are made from the V_BAT side of the instruments.
The PPK2 is used to provide the V_BAT voltage to our instruments (in this case it was 3V)(and also to check the currents).
The load profile is a constant charge which is around 6 uA with a V_OUT of 3V (the instrument is in the OFF mode).

Ok I can send the schematics of the NPM2100 in a techsupport case.

The capacitor is not 100 uF but 10 uF instead (which is a recommanded value given by your team).
I just confirmed that with the schematics.

We know this point about the PPK2. Sometime the PPK2 gives a wrong current with those high frequencies.
We use an amperemeter (in uA range) to check the values given by the PPK2.
With this option, the current of the PPK2 are quite the same as the one given by the amperemeter.

I look forward hearing from you soon.

Best regards,

RE: nPM2100 : stabilisation of the current consumption when the output power is low

Audun — Wed, 10 Sep 2025 07:42:06 GMT

Hi SCF ,

For this use case, "auto mode" is recomended. This will cause the BOOST regulator to automatically use pass-through mode when VBAT > VOUT. No need to change BOOST.GPIO, BOOST.PIN or BOOST.OPER registers in this case.

These PPK2 measurements are taken from the VBAT side? That is, PPK2 is acting as a power supply for VBAT? What does the VOUT load profile look like at this time?

Would it also be possible to look at the schematics for the nPM2100 to see if there could be potential issues? That can be done via a private techsupport case.

The "discharge"-type behavior makes me wonder if there could be capacitance somewhere that affects performance.

I tried to recreate the behavior on an nPM2100 EK, but I have been unsuccessful so far. This is the profile I see when connecting and disconnecting a 10 mA constant current load, using 100 uF VINT capacitance:

Note that the PPK2 struggles a bit when measuring the nPM2100 (and other BOOST converters presumably), due to the very short current spikes seen on the VBAT side. The 100 kHz sampling rate of the PPK2 does not capture all of these, and it is easy to get an underestimated current measurement value.

Best regards,

Audun

RE: nPM2100 : stabilisation of the current consumption when the output power is low

SCF — Tue, 09 Sep 2025 13:28:04 GMT

devzone.nordicsemi.com/.../OFF.zip

Here I send the complete measurment I made with the PPK2