ROHM Battery Charger IC: Charging Low-Voltage Rechargeable Batteries

Willich-Münchheide, Germany, November 16, 2021 – ROHM developed a battery charger IC – BD71631QWZ – designed to provide low-voltage charging of wearables like wireless ear buds and thin, compact IoT devices such as smart displays powered by rechargeable batteries.

In recent years the need for safer, higher density rechargeable batteries has led to the development of new battery types. This includes all-solid/semi-solid types models using novel materials for the electrode part and batteries that adopt different terminal compositions. However, many of the latest rechargeable batteries are small and thin, requiring low voltage charging in the 2V to 3V range. Moreover, there are currently no battery charger ICs that can handle a wide voltage range.

Based on this market demand, ROHM developed a battery charger IC that supports low voltage charging of not only li-ion, but also new types of rechargeable batteries such as all-solid and semi-solid state. The BD71631QWZ achieves low voltage charging over a wide range from 2.0V to 4.7V by improving the stability of the internal circuit.

Unlike general battery charger ICs that provide a fixed voltage, ROHM’s new product allows the charge voltage to be easily set by simply changing the external resistor, reducing design load when changing batteries. Additionally, original package technology results in a compact package just 0.4mm thickness, which is 60% lower than conventional products in market. This is contributing to smaller, thinner devices. In addition, each charging characteristic like charge/termination current can be set for CCCV charging, providing an optimal charging environment for thin, compact IoT and wearable devices utilizing the latest rechargeable batteries.

Going forward, ROHM will continue to contribute to providing greater application convenience by supplying more efficient charging solutions.

Product Lineup

Application Examples

• Devices equipped with low voltage and single-cell li-ion rechargeable batteries
• Wearables such as wireless ear buds, electronic pens, e-cigarettes, etc.
• Smart displays/tags and other compact IoT devices

Evaluation Board