The LTC3555 family are highly integrated USB compatible power management and battery charger ICs for Li-Ion/Polymer battery applications. They include a high efficiency 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 available from the USB port to the load with minimal loss and heat which eases thermal constraints in small spaces.Two of the three general purpose switching regulators can provide up to 400mA and the third can deliver 1A. The entire product can be controlled via I2C or simple I/O. The LTC3555-1/LTC3555-3 versions offer "instant-on" power delivery to the portable product even with a very low battery voltage. The LTC3555-3 version also has a reduced charger float voltage of 4.100V for battery safety and longevity.The LTC3555 family is available in the low profile 28-pin (4mm × 5mm × 0.75mm) QFN surface mount package.ApplicationsHDD-Based MP3 Players, PDAs, GPS, PMPsPortable Medical ProductsHandheld InstrumentationOther USB-Based Handheld Products