Deutsch  |  Français  |  Italiano  |   简体中文  |  繁體中文  |  日本語  |  한국어

Linear USB Power Manager Handles Power Selection, Battery Charging & Integrates Three Buck Regulators

MILPITAS, CA - July 5, 2007 - Linear Technology Corporation announces the LTC3557, a multi-function power management solution for Li-Ion/Polymer battery applications. The LTC3557 integrates a linear PowerPath™ manager, a standalone battery charger, ideal diode, three high efficiency synchronous buck regulators and an always-on LDO in a low-profile 4mm x 4mm QFN package. The powerpath manager seamlessly manages the transition between multiple input sources and power to the load, while for fast charging the linear battery charger delivers up to 1.5A charge current from a wall adapter supply or up to 500mA charge current from a USB port. The LTC3557's three integrated synchronous buck regulators feature 100% duty cycle operation and are capable of delivering output currents of 600/400/400mA respectively, with adjustable output voltages down to 0.8V. The high 2.25MHz switching frequency allows the use of tiny low cost capacitors and inductors less than 1mm in height. The internal low RDS(ON) switches enable efficiencies as high as 95%, maximizing battery run time. In addition, pin-selectable Burst Mode® operation optimizes efficiency at light loads with a quiescent current of only 35uA per regulator (

The LTC3557's standalone autonomous operation simplifies design, eliminating the need for an external microprocessor for charge termination. To preserve battery energy, the IC draws

The LTC3557 is available from stock in a compact, low-profile (0.75mm) 4mm x 4mm QFN-28 package. Pricing starts at $3.95 each for 1,000-piece quantities.

Summary of Features: LTC3557 •  Complete Multi-Function ASSP: Linear Power Manager, Li-Ion/Polymer Battery Charger & Three Synchronous Buck Regulators •  Thermally Enhanced, Low Profile (0.75mm) 28-Lead 4mm x 4mm QFN Package POWER MANAGER & BATTERY CHARGER •  Charge Current Programmable up to 1.5A from Wall Adapter Input •  Seamless Transition Between Input Power Sources: Li-Ion Battery, USB, 5V Wall Adapter or High Voltage Buck Regulator with Bat-Track Adaptive Output Control •  200mOhm Internal Ideal Diode Plus Optional External Ideal Diode Controller Provides Low Loss Power Path from Battery to Load •  Standalone Autonomous Operation DC/DCs •  Three High Efficiency Synchronous Buck Regulators with Pin Selectable Burst Mode Operation •  Buck Regulator Adjustable Output Voltage Range: 0.8V to VBAT •  Buck Regulator Output Currents: 600mA, 400mA, 400mA •  Always-On 25mA/3.3V LDO

Multi-Function Linear Power Manager + Battery Charger + Triple Sync Buck Click Photo for High-Res Image