Power by Linear™/Analog Device’s LTC4126 is a low-power wireless single-cell Li-Ion battery charger. This battery charger comes with an integrated step-down (buck) DC/DC regulator. The step-down regulator is a low-noise multimode charge pump which is powered from the battery and provides a regulated 1.2 V at the output. The switching frequency is set to either 50 kHz or 75 kHz depending on the mode to keep any switching noise out of the audible range.

The LTC4126 charger is a full-featured constant-current constant-voltage Li-Ion battery charger with automatic recharge, automatic termination by safety timer, and battery temperature monitoring via an NTC pin. Charge current is fixed at 7.5 mA with a six hour termination timer. Undervoltage protection disconnects the battery from all loads when the battery voltage is below 3.0 V. The battery charger comes in a small 2 mm × 2 mm LQFN package with an operating temperature range of -20°C to +85°C. The LTC4126 is ideal for Li-Ion battery powered hearing aids, IoT wearables, and wireless headset applications as well as other low power portable devices where a small solution size is required.