Author: Moondust Knowledge Engineers

Primary cell batteries have become the go-to solution for countless devices thanks to their low cost, easy integration, and impressive longevity. Today’s ultra-low-power electronics can run for years before needing a replacement, which has fostered a “fit-and-forget” mindset. But no matter how efficient the design, stored power eventually runs out, often leaving valuable unused energy behind.

Most devices powered by primary cells operate without power management. They rely on stable voltage, and once the battery dips below the circuit’s minimum threshold, it is simply replaced. Many modern ICs can tolerate supply ranges from 1.8 V to 3.4 V. Still, in practice, batteries often get swapped before their true capacity is fully tapped. Considering the millions of primary cells discarded daily, there is a clear need for solutions that squeeze every last bit of energy out of them.

Image source: Nordic Semiconductor

The Role of the Boost Converter

This is where a boost converter proves valuable. By extracting energy even when voltage falls below operational limits, it allows devices to operate longer. While some power management ICs already include boost converters, they tend to be complex, bulky, and tailored for multi-rail systems, not compact devices running on a single primary cell.

A Purpose-Built Solution

Enter Nordic Semiconductor’s nPM2100. It is the company’s first PMIC designed specifically for primary cell applications and also their smallest yet at just 1.9 mm by 1.9 mm in chip-scale packaging. Unlike conventional PMICs, the nPM2100 was created to extend the usable lifetime of batteries in ultra-low-power devices, whether connected or standalone.

Nordic primarily designed it to support its wireless technologies like Bluetooth, Thread, Matter, and Zigbee. Yet, the nPM2100 is versatile enough for any battery-powered system that requires efficiency, stability, and compactness.

Key Features that Set It Apart

The nPM2100 delivers several power-optimized features that make it stand out:

• An ultra-efficient boost converter with up to 95% efficiency
• A factory-ready ship mode so devices can ship with batteries pre-installed
• Hibernate mode with a sleep timer to extend battery longevity
• A smart fuel gauge that estimates battery lifetime more accurately

The boost converter is particularly impressive. It can sustain an output voltage between 1.8 and 3.3 V even when input voltage drops as low as 0.7 V. Once the battery dips below 3.0 V, the boost converter activates and keeps delivering reliable power until the absolute minimum is reached. This allows the nPM2100 to consistently supply 3.3 V at up to 150 mA, provided the cell’s internal resistance doesn’t limit input current.

In addition, the PMIC integrates an LDO regulator controlled via I²C. This can deliver up to 50 mA with an adjustable output from 0.8 V to 3.0 V, offering flexibility for different loads.

Modes that Maximize Efficiency

Factory-installed batteries not only improve the consumer’s unboxing experience but also reduce waste by eliminating isolation tags and extra packaging materials. Nordic’s ship mode supports this approach by cutting power draw to just 35 nA, less than the self-discharge current of common alkaline or lithium manganese dioxide cells.

Devices can exit ship mode programmatically or via the SHPHLD pin, which can be configured to wake the PMIC on a rising or falling edge, or even by breaking a ground connection.

For everyday use, hibernate mode offers another layer of efficiency. Consuming only 175 nA, it lets the PMIC sleep while using its internal timer to wake periodically. With a maximum sleep cycle of three days, this mode extends battery life without compromising responsiveness.

Smarter Battery Insight

Measuring battery voltage alone does not provide a clear picture of remaining capacity, since temperature significantly affects performance. Nordic addresses this challenge with a software-based fuel gauge that combines voltage and temperature data. By applying algorithms tuned to specific chemistries, devices can predict battery life more accurately, ensuring timely replacement without unnecessary waste.

Additional Capabilities

The nPM2100 integrates two GPIO pins configurable via registers, an ADC for monitoring voltage and temperature, and essential functions like a boot monitor and watchdog timer. These ensure reliable operation by resetting or cycling the system if it encounters errors during boot or runtime.

Why It Matters

For applications such as smart sensors, medical devices, and other compact systems, every microamp counts. With peak current support of 150 mA and efficiency levels up to 95%, the nPM2100 sets a new standard for primary cell battery management.

By enabling longer lifetimes, reducing e-waste, and enhancing the user experience, Nordic’s nPM2100 goes beyond simply powering devices. It redefines how engineers can harness every last bit of stored energy from primary cells.