USB Power Manager Integrates Buck Regulators

The LTC3557 from Linear Technology is a multi-function power management solution for Li-ion or Li-polymer battery applications that integrates a linear PowerPath manager, a standalone battery charger, ideal diode, an always-on LDO, and three high-efficiency synchronous buck regulators. Standalone autonomous operation simplifies design, eliminating the need for an external microprocessor for charge termination.

The three buck regulators feature 100%-duty-cycle operation and can deliver output currents of 600 mA, 400 mA and 400 mA, respectively. The PowerPath manager seamlessly manages the transition between multiple input sources and power to the load; for fast charging the linear battery charger delivers up to 1.5 A from a wall adapter, or up to 500 mA from a USB port, with adjustable output voltages down to 0.8 V. The switching frequency is 2.25 MHz, and efficiency reaches 95%. The LTC3557 is available now in a 0.75-mm profile, 4 mm x 4 mm QFN-28 package. Pricing starts at $3.95 each for 1000-piece quantities.