Low-power battery management for wearables/IoT

October 02, 2015 // By Graham Prophet
Texas Instruments has added an integrated battery management IC, claiming the lowest-available quiescent current (Iq) at 700 nA with the buck converter, operating at 1.8V. The bq25120 features a linear charger, configurable LDO, load switch, buck converter, pushbutton control and battery voltage monitor all in one.

The device supports batteries from 3.6V to 4.65V, and fast charge currents from 5 mA to 300 mA, allowing wearables and industrial Internet of Things (IoT) applications to always be on without draining the battery.

The bq25120 maintains an always-on 1.8-V operation using power path technology and a low Iq buck converter. A host microprocessor or Bluetooth radio is able to continue running during recharging by not extracting “empty energy.” Designers can also achieve the longest battery shelf life as the solution features standby mode quiescent current of 50 nA.

High integration incorporates a configurable load switch/LDO output that shuts off rarely used functions such as radios and displays to minimise battery drain. The solution also includes an integrated battery voltage monitor, enabling a state of charge indicator, buck converter and pushbutton control features.

A 2.5-mm by 2.5-mm WCSP package enables a small footprint for wearable designs. Designers can incorporate the CC2640 wireless MCU as it is the industry’s smallest QFN package solution with integrated Flash for Bluetooth Smart.

Accurate charge termination down to 500 µA: this feature maximizes the energy delivered to the battery before completing the charging cycle, allowing batteries to draw a more robust full charge. The bq25120’s I ²C programming interface gives designers the ability to set key parameters including battery charger voltage, current, termination threshold, input current limit, load switch control, flexible timer and reset options and more.

The bq25120 evaluation module (EVM), BQ25120EVM-731, is $99; The bq25120 is priced at $1.60 (1000).

TI; www.ti.com/bq25120-pr-eu.