NPM1300 on custom board cannot start battery charging

RE: NPM1300 on custom board cannot start battery charging

Simonr — Wed, 12 Nov 2025 11:07:30 GMT

Hi Per

NTC connected to GND or a 10k resistor are both valid designs, depending on whether you'd like to have automatic recharge and battery temperature monitoring enabled or not.

Adding a device tree option is a good suggestion and I'll make a note of that. Let me know if there are any more questions before closing out this ticket.

Best regards,

Simon

RE: NPM1300 on custom board cannot start battery charging

Perre — Tue, 11 Nov 2025 21:02:07 GMT

Just want to confirm the 'patch' worked well... but not very nice as a permanent solution.
Anyway, I'm pleased now!!

For someone else having this issue... one can probably clean it out a bit..

Add in the npm init() routine

struct npm13xx_charger_config {

const struct device *mfd;

};

// Patch to not using NTC.. we need to tell pmic not to care about temperature

// chargerbase = 0x03

// register = 0x06

// write value = 0x02

const struct npm13xx_charger_config *const config = charger->config;

mfd_npm13xx_reg_write(config->mfd,0x03,0x06,0x02);

RE: NPM1300 on custom board cannot start battery charging

Perre — Tue, 11 Nov 2025 08:16:43 GMT

ah, ok. I will try. Thanks..

A final question,

How would a new design look like?

Should then NTC be connected to GND (with IC2 register write) or to a 10K resistor (without register write)?

Or should there be a device tree option where you choose 'Not_use_NTC' regardless of how NTC pin is connected?

RE: NPM1300 on custom board cannot start battery charging

Simonr — Tue, 11 Nov 2025 06:54:50 GMT

Feedback from the developers on this: If NTC is not used and NTC is connected to GND, you also ened to disable battery temperature monitoring in the SW with the BCHGDISABLESET register. See page 29 in the product specification for details.

So seems like a patch isn't necessary, but rather a setting in SW is required when NTC is not in use.

Best regards,

Simon

RE: NPM1300 on custom board cannot start battery charging

Perre — Mon, 10 Nov 2025 18:47:31 GMT

well, I found that you have described this issue actually.. or at least for the fuelgauge example in the latest SDK.

ok, this means that now the NTC must be connected to vddio via 10k ohm.

But for existing design I think there should be a patch.

Please also update reference schematic npm1304..

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/releases_and_maturity/releases/release-notes-3.1.1.html#pmic_samples

RE: NPM1300 on custom board cannot start battery charging

Simonr — Mon, 10 Nov 2025 13:41:34 GMT

Hi Per

I have reported this to the developers now, and we're looking into it. I'll get back to you by the end of week at the latest with an update on this issue. Thank you for your thorough investigation, this does indeed seem like a bug to me.

Best regards,

Simon

RE: NPM1300 on custom board cannot start battery charging

Perre — Sun, 09 Nov 2025 21:06:29 GMT

Now I have dived deeper into this issue and here my conclusion,

Its correct that the fuelgauge works well in nrf sdk 3.1.1. I have tried it with the nrf54L15 dk together with npm1304 dk.
But not working with my custom board. I2C works well but not the charging. (tried with pull-up resistors 10K)
My board has the NTC pin connected to ground as suggested in the npm1304 datasheet.
If I connect NTC to ground on npm1304 dk(instead of 10k ohm), I will end up in charging not working. Same symptoms as with my custom board. Fuel gauge will say 'Charger idle' regardless if I connect or dissconnect VBUS.

connecting the NTC to ground worked well in nrf sdk 3.0.1 but not in the latest sdk. In latest SDK NTC cannot be connected to GND or floating. Must be connected to VDDIO via 10K(?)

Can you please verify if my conclusion is correct. And if soo.. is it then possible to get a patch.. as a new pcb will take some time to create?

RE: NPM1300 on custom board cannot start battery charging

Simonr — Fri, 17 Oct 2025 06:23:27 GMT

Hi Per

There were some changes to add support for both the nPM1300 and nPM1304 in NCS 3.1.1, so some extra build configs must be added to get the nPM Fuel Gauge sample to work correctly. The Extra CMake argument and Extra Devicetree overlay seen here must be added for the sample to build correctly:

This is also described in the 3.1.1 page of the documentation: https://docs.nordicsemi.com/bundle/ncs-3.1.1/page/nrf/samples/pmic/native/npm13xx_fuel_gauge/README.html

I can confirm the sample builds for the nRF54L15 DK with these build configs.

Best regards,

Simon

RE: NPM1300 on custom board cannot start battery charging

Perre — Wed, 15 Oct 2025 19:02:12 GMT

I have rationalised away some componetnts. But have not had any issues from that yet. I dont see those have anything to do with the charging problem.

I have tried some more with yet another board but with the same problem. No charging.

vbatlow does not help.

I dont have the time right now do dig deeper and I revert back to sdk 3.0.1 and continue my testing.. and hope some else find a solution.

By the way, the fuelgauge example in sdk 3.1.1 is not possible to compile with nrf54L15. I guess no one have tested the fuel gauge on sdk 3.1.1.

You may close the ticket...

RE: NPM1300 on custom board cannot start battery charging

Simonr — Tue, 14 Oct 2025 08:42:47 GMT

From your schematic it seems like you haven't followed our reference schematic guidelines, with input capacitors from the battery and VBUS inputs missing, and pull-up resistors on SDA/SCL missing.

That being said there shouldn't be a specific reasaon upgrading to NCS 3.1.1 should break charging. However, is VBUS connected when the battery is removed and plugged back in? If not, this will power cycle the PMIC, and should not cause problems in a design where the PMIC powers the SoC. But, if the SoC is powered separately, the scenario you describe will result in an uninitialized PMIC since the SoC won't execute the init code without a power cycle/reset, and thus charging would be disabled by default.

And finally, can you try uncommenting this line in your charger config file and see if that makes a difference?

// vbatlow-charge-enable;

Best regards,

Simon