DESCRIPTION
The LTC®3456 is a complete power management system IC optimized for a variety of portable applications. The device generates two separate power rails: a 3.3V (fixed) Main supply and a 1.8V (adjustable) Core supply. In addition, the LTC3456 contains a USB power manager, a Hot Swap output, a low-battery indicator and an always-alive VMAX output. The LTC3456 takes power from one of three sources: a Wall adapter, a USB port or a 2-cell Alkaline/NiCd/NiMH battery, in that order of priority. Current drawn from the USB port is accurately limited to 100mA or 500mA based on the state of the USBHP pin.

FEATURES
■ Seamless Transition Between 2-Cell Battery, USB
   and AC Wall Adapter Input Power Sources
■ Main Output: Fixed 3.3V Output
■ Core Output: Adjustable from 0.8V to VBATT(MIN)
■ Hot SwapTM Output for Memory Cards
■ All Outputs Discharged to Ground During Shutdown
■ Power Supply Sequencing: Main and Hot Swap
   Outputs Come Up After Core Output
■ Accurate USB Current Limiting
■ High Frequency Operation: 1MHz
■ High Efficiency: Up to 92%
■ Small (4mm × 4mm × 0.75mm) 24-Pin QFN Package

APPLICATIONS
■ GPS Portable Navigators
■ MP3 Players
■ Digital Cameras
■ Handheld Computers