USB power manager maximizes battery runtime, minimizes heat

PMIC integrates multiple functions in low-profile QFN package

The LTC3556 multifunction power management IC for Li-ion/polymer battery applications integrates the company's switching PowerPath manager, a stand-alone battery charger, an ideal diode, an I2C control, a synchronous buck-boost regulator, two synchronous buck regulators plus an always-on LDO -- all in a compact, low-profile 4 x 5-mm QFN package. It seamlessly manages power flow between multiple input sources such as a wall adapter or USB port and the lithium battery while preferentially providing power to the system load. In addition, its instant-on operation ensures system load power even with a dead or missing battery.

The switching input stage converts nearly all of the 2.5 W available from the USB port to charging current, enabling up to 700 mA from a 500-mA USB supply or up to 1.5 A when wall powered. An internal 180-mΩ ideal diode and optional external ideal diode controller provide a low-loss power path. The onboard synchronous buck-boost regulator can deliver up to 1 A continuously and is suited for regulating a 3.3-V output voltage over the full lithium battery voltage range, down to 2.75-V input. The LTC3556 features USB-compatible programmable current limiting to 100 mA/500 mA/1 A. It draws 44 µA in suspend mode. The charger is compatible with inputs up to 5.5 V. (From $4.80 ea/1,000 -- stock.)

Linear Technology, Milpitas, CA
Information 408-432-1900
http://www.linear.com