General Description
The MAX1538 selector provides power-source control for dual-battery systems. The device selects between an AC adapter and dual batteries based on the presence of the three power sources and the state of charge of each battery.

Features
♦ Automatically Detects and Responds to
   Low-Battery Voltage Condition
   Battery Insertion and Removal
   AC-Adapter Presence
   Airline-Adapter Presence
♦ Step-Down and Step-Up Charger Compatibility
♦ Fast Break-Before-Make Selection
   Allows Hot Swapping of Power Sources
   No External Schottky Diodes Needed
♦ 50µA Maximum Battery Quiescent Current
♦ Implements Battery Capacity Relearning
♦ Allows Usage of Aircraft Supply
♦ Direct Drive of P-Channel MOSFETs
♦ Simplifies Power-Management µP Firmware
♦ 4.75V to 28V AC-Adapter Input Voltage Range
♦ Small 28-Pin Thin QFN Package (5mm x 5mm)