Powering portables

Texas Instruments has developed a charge and power management chip that combines a single-cell Li-Ion USB/AC charger with a synchronous DC/DC power converter.

The bq25010 device gives portable equipment designers the ability to charge a battery either from an AC adapter or USB with autonomous power source selection. The IC integrates a power FET and current sensor to deliver up to 500-mA, while the USB charge control limits the USB current to 100-mA or 500-mA.

The IC also incorporates a 100-mA step-down DC/DC converter. Under nominal load current, operating at a fixed switching frequency of 1 MHz, the device achieves up to 95% conversion efficiency. At lighter load currents, it enters a "power save mode" with reduced switching frequency and a minimum quiescent current to maintain high efficiency. The converter also operates directly from the battery and regulates the output voltage, even when the input supply is removed.

The bq25010 integrated charger is in volume production from TI and its authorized distributors. The bq25010 has an adjustable output voltage of 0.7V to 4.2V. Another family member, the bq25012, comes with a fixed output voltage of 1.8V.