Description:
Hello Nordic team,
I’m using the Mikroe nPM1300 PMIC Click Board (based on the Nordic nPM1300 PMIC) with an ESP32 over I²C to charge a Li-ion battery.
I am observing two issues related to the charging behavior.
Setup details:
-
Battery: 3.7 V nominal, 950 mAh Li-ion
-
Configured charge current: 800 mA
-
Termination voltage (VTERM): 4.20 V
-
Termination current: 20% of charge current (~160 mA)
-
VBUS current limit: 1500 mA (set manually via I²C)
-
NTC monitoring: Disabled
- Power source: 5 V adapter connected to VBUS
- Communication: I²C via ESP32 MCU
Issue – First USB connection starts in constant-voltage (CV) mode:
When the board is powered for the first time and a battery (~3.6–3.8 V) is connected, the charger immediately enters CV mode instead of constant-current (CC) mode.
If I remove and reconnect the USB power, charging starts correctly in constant-current mode and later transitions to CV mode as expected near 4.2 V.
Questions:
-
Is there a known condition where the nPM1300 starts in CV mode after power-up?
-
Should I trigger a specific charger task (e.g.,
TASKCHARGERSTART) after VBUS connection to properly initialize the charge cycle? -
Could the VBUS current limit or ADC enable sequence affect the initial charging phase detection?
-
Are there recommended register writes or startup sequences to ensure proper CC-to-CV transition behavior?
