Nordic PMIC features 8 µA fuel gauging for small battery devices

Nordic Semiconductor has announced the nPM1304 Power Management IC (PMIC) designed for space-constrained applications requiring small batteries. The nPM1304 complements Nordic’s nPM1300 PMIC with integrated power management and precision fuel gauging for smart rings, body sensors, and other small battery applications.

The nPM1304 PMIC provides system management features and accurate fuel gauging for low-power, size-constrained applications. Nordic’s algorithm-based fuel gauge method uses voltage, current, and temperature monitoring combined with a mathematical battery model to estimate battery state of charge. This method delivers accuracy comparable to dedicated fuel gauge devices such as coulomb counters without additional power consumption and inherent error accumulation.

Traditional dedicated fuel gauge devices consume up to 50µA when active and 7µA in sleep mode. For products with 200µA average current consumption, conventional fuel gauging represents a significant portion of the total energy budget. Nordic’s solution uses 8µA active current and zero current in sleep mode, providing accurate state-of-charge estimates without measurable impact on battery life.

The nPM1304 charges single-cell Li-ion, Li-poly, and LiFePO4 batteries through a linear charging module supporting 4 to 100 mA charge current with programmable termination voltage from 3.5 to 4.65 V. The battery charger includes automatic thermal regulation with programmable maximum chip temperature during charging.

The nPM1304 targets end products with small rechargeable batteries, including smart rings, sports performance trackers, and personal health care monitoring devices. The device manages power supply for Nordic’s nRF52, nRF53, and nRF54 Series wireless Systems-on-Chip (SoCs) and other microcontrollers, optimizing for efficiency and compact size.

The nPM1304 includes the same system features as the nPM1300 PMIC. Beyond battery charging and fuel gauging, it incorporates two buck converters, two load switches/Low Drop Out voltage converters (LDOs), 5 GPIOs, and 3 LED drivers. The device features an I2C-compatible Two Wire Interface (TWI) for configuring system management functions, including integrated hard reset functionality from one or two buttons, battery fuel gauging, system-level watchdog, power loss warning, and recovery from failed boot. The device reduces end-product Bill-of-Materials by combining circuitry that typically requires five or more discrete components into a single chip.