The LTC1473L provides reliable and efficient switching between two DC power sources. This device drives two external sets of back-to-back N-channel MOSFET switches to route power to the input of a low voltage system. An internal boost regulator provides the voltage to fully enhance the logic-level N-channel MOSFET switches while an internal undervoltage lock-out circuit keeps the system alive down to 2.8V.The LTC1473L senses current to limit inrush between the batteries and the system supply capacitor during switch-over transitions or during fault conditions. A user-programmable timer monitors the time the MOSFET switches are in current limit and latches them off when the programmed time is exceeded.A unique "2-diode" logic mode ensures system start-up regardless of which input receives power first.ApplicationsPortable ComputersPortable InstrumentsFault Tolerant ComputersBattery-Backup Systems3.3V/5V Power Management