DESCRIPTION
The LTC®3555 family are highly integrated USB compatible power management and battery charger ICs for Li-Ion/Polymer battery applications. They include a high effi ciency current limited switching PowerPath manager with automatic load prioritization, a battery charger, an ideal diode and three general purpose synchronous step-down switching regulators.
The LTC3555 family limits input current to either 100mA or 500mA for USB applications or 1A for adapter-powered applications. Unlike linear chargers, the LTC3555 family’s switching architecture transmits nearly all of the power avail able from the USB port to the load with minimal loss and heat which eases thermal constraints in small spaces.

FEATURES
Power Manager
■ High Effi ciency Switching PowerPath™ Controller with Bat-Track™ Adaptive Output Control
■ Programmable USB or Wall Current Limit (100mA/500mA/1A)
■ Full Featured Li-Ion/Polymer Battery Charger
■ 1.5A Maximum Charge Current
■ Internal 180mΩ Ideal Diode + External Ideal Diode Controller Powers Load in Battery Mode
■ Low No-Load Quiescent Current when Powered from BAT (<32μA)

DC/DCs
■ Triple High Effi ciency Step-Down DC/DCs (1A/400mA/400mA IOUT)
■ All Regulators Operate at 2.25MHz
■ Dynamic Voltage Scaling on Two Outputs
■ I2C or Independent Enable, VOUT Controls
■ Low No-Load Quiescent Current: 20μA
■ 28-Pin (4mm × 5mm × 0.75mm) QFN Package

APPLICATIONS
■ HDD-Based MP3 Players, PDAs, GPS, PMPs
■ Portable Medical Products
■ Handheld Instrumentation
■ Other USB-Based Handheld Products