Ultra-low power conversion for wearable, sensor and industrial designs

September 11, 2014 // By Graham Prophet
Texas Instruments claims to have the industry’s smallest and lowest-power battery charger, for use with ultra-low-power designs, such as wearables and remote sensor nodes; and TI offers the first fully integrated 360 nA quiescent-current MicroSiP power module help extend battery run-time

This introduction comprises a very small and low power linear battery charger and a tiny, fully integrated DC/DC power module, which consumes only 360 nA of quiescent current, to help extend battery run-time in wearable electronics, remote sensors and MSP430 microcontroller-based applications.

The bq25100 single-cell Li-Ion charger comes in a 0.9 x 1.6-mm WCSP package, and achieves a solution half the size of existing charger solutions. The device supports input voltages up to 30V, and allows accurate control of fast-charge currents as low as 10 mA or as high as 250 mA, and precise charge termination down to 1 mA, to support tiny Li-Ion coin batteries. The bq25100 also has a leakage current of less than 75 nA to extend standby operation.

Designers also can add wireless charging capability to small portable and wearable applications by pairing the bq51003 2.5-W, Qi-compliant wireless charging receiver with the bq25100 linear charger on the same board. Both devices are featured on a TI Design reference board that occupies 75 square mm.

The TPS82740A and TPS82740B step-down converter modules support 200-mA output current with 95% conversion efficiency and have an IQ of 360 nA during active operation and 70 nA during standby. The tiny modules rely on a fully integrated, 9-bump MicroSiP package, which incorporates a switching regulator, inductor and input/output capacitors to achieve a solution size of only 6.7 mm².

The TPS82740A supports output voltages from 1.8V to 2.5V, while the TPS82740B supports 2.6V to 3.3V in 100-mV steps, which can meet power requirements of MCUs such as TI's ultra-low power MSP430FR59xx microcontrollers (MCUs), and Bluetooth low energy solutions, such as the SimpleLink CC2540T wireless MCU.

With the TPS82740A and TPS82740B, TI says, you can build the smallest 200-mA DC/DC solutions: the fully integrated MicroSiP modules include all passives.

The bq25100 is $0.75 (1000), and it has the bq25100EVM-654 evaluation module. The TPS82740A and TPS82740B power modules measuring 2.3 x 2.9 x 1.1