Optimized for small batteries with integrated regulator and charger
Current and voltage adjustment possible with battery temperature monitoring function

Wearable devices are being used for a variety of purposes, including smart belts that record daily activity and alert you to overeating, and wearable cameras that attach to bags or clothing to capture daily photos. Furthermore, with the advent of "hearables," wearable devices in the form of earphones inserted into the ear, devices are becoming smaller and more wireless.

Hearable devices must be small and incorporate a variety of sensors, including accelerometers and heart rate sensors, necessitating smaller components. Most PMICs for small devices powered by lithium-ion batteries require current regulators such as boost, buck, LDO, regulator charger, and LED indicators.

Maxim Integrated has introduced the MAX77650 and MAX77651, which enable compact power solutions that are less than half the size (19.2mm2) of conventional PMICs. Both products are designed for low-power wearables where size and efficiency are paramount. Both devices feature three independently programmable power rails on a single inductor and SIMO buck-boost regulation to minimize overall solution size.

It also includes features such as a current sink for driving LED indicators and an analog multiplexer for switching multiple internal voltage and current signals to external nodes for monitoring with an external ADC. A 150mA LDO provides ripple rejection for audio and other noise-sensitive applications. It supports a wide range of lithium-ion battery capacities and features battery temperature monitoring for safety.

This charger is optimized for small batteries, with a low standby current of 0.3 μA and a programmable fast-charge current of 7.5 mA to 300 mA. Battery temperature monitoring allows for adjustment of the charge current and regulation voltage.

Regarding the demand for battery management chips, Richard Eden, senior analyst for power semiconductors at IHS Markit Technology, said, “A compound annual growth rate of 5% is expected from 2017 to 2020,” and analyzed that “battery management for wearables, including hearables, will show the highest average annual growth rate of 29% during the same period.”

“The MAX77650 and MAX77651 leverage Maxim’s PMIC expertise to deliver ultra-small, ultra-low-power battery-charging solutions that address the growing market need,” said Scott Kim, business manager for mobile power at Maxim Integrated. “Both solutions are optimized for small batteries.”

“The MAX77650, with its rich feature set ideal for wearables, has enabled us to reduce the size of our Bluetooth music headsets,” said Tjapko Uildriks, CEO of Dopple BV. “The MAX77650 integrates essential power management features required for advanced wearables, enabling Dopple to build a high-quality Bluetooth music headset platform.”