nPM1300 PMIC not powering consistently with nRF9151 custom PCB

[Rahul Chavda]

Hello Nordic Team,

We have developed a custom PCB using nRF9151 and nPM1300.
In our setup, sometimes the PMIC powers up and works correctly, but other times it does not start at all. We are not sure what is causing this issue.

Hardware configuration:

• Battery: 3.7 V Li-Po, 600 mAh

• nPM1300 connections:

  • VSYS → connected to nRF9151 VDD

  • BUCK1 (VOUT1 = 1.8 V) → supplies nRF9151 GPIO (VDD_GPIO) and I²C pull-ups

  • BUCK2 (VOUT2 = 3.3 V) → used for other modules

  • LDO1 and LDO2 also enabled for additional 1.8 V and RTC supplies

  • I²C pull-ups: 4.7 kΩ to 1.8 V (BUCK1 output)

Issue details:

• Sometimes the PMIC powers the system normally.

• Other times, it doesn’t start unless we connect the nRF Desktop App (nRF Connect) through the debugger (SWD pins: SDIO, SCLK, RESET).

• When connected via debugger, we can scan the PMIC over I²C and see 1.8 V output on BUCK1 and BUCK2, and both LDOs turn on as expected.

• When running from battery only (without debugger connected), the PMIC sometimes fails to start.

Could you please help us understand why the nPM1300 is not consistently powering up the system?
Do we need any specific enable or power-up sequence between the PMIC and nRF9151?



            

[Kazi Afroza Sultana]

I can see you also have LDO1 and LDO2 for additional 1.8V and RTC supplies.

We have an errata [41] LOADSW/LDO: LDO startup might cause reset for Engineering revision E about the resetting of the device at LDO startup due to voltage drop on VBAT. When the device is powered from VBAT, LDO is supplied by VSYS; If VBAT voltage level goes below 300mV during starting up in LDO mode, device resets.

You can also check if VDDIO and VOUT1 is connected by jumper.

Thanks.

BR

Kazi

[Rahul Chavda]

Hello Nordic Team,

We are using nRF9151 with nPM1300 PMIC and some other peripheral devices in our custom design.

We have observed an issue with LDO1 on the nPM1300.
When we power the system from a battery (connect or disconnect the battery), sometimes LDO1 does not start properly — instead of 1.8 V, we see random voltages between 300 mV to 700 mV.

[Kazi Afroza Sultana]

Hello,

You can try to look at this errata nPM1300_Rev_2_Errata_v1.1.pdf.