USB Power Solution Includes Switching Power Manager,Battery Charger, Three Synchronous Buck Regulators and LDLinear Technology offers a variety of parts to simplify the
task of extracting power from a battery or a USB cable. These
devices seamlessly manage the power fl ow between an
AC adapter, USB cable and Li-Ion battery, all while maintaining
USB power specifi cation compliance. As battery
capacities rise, battery chargers must keep pace by
steadily improving effi ciency to minimize thermal concerns
and charge times. A USB-based battery charger must
squeeze as much power from the USB as possible, and
do it effi ciently to meet the stringent space and thermal
constraints of today’s power-intensive applications.
The LTC?3555 combines a USB switching power manager
and battery charger with three synchronous buck regulators
and an LDO to provide a complete power supply
solution in one small (4mm × 5mm) package (Figure 1).
The constant-current, constant-voltage Lithium-Ion/Polymer
charger utilizes a Bat-Track? feature to maximize the
effi ciency of the battery charger by generating an input
voltage that automatically tracks the battery voltage
(described below). An I2C serial interface affords the
system designer complete control over the charger and
the DC/DC bucks for ultimate adaptability to changing
operating modes in a wide range of applications.