Microchip MCP1643 1MHz Synchronous Boost LED Constant Current Regulator is optimized to drive one LED with constant current that operates from one and two-cell alkaline and NiMH/NiCd batteries. This Microchip device can also drive two red/green/yellow series connection LEDs. Low-voltage technology allows the regulator to start up without high-output voltage and load-current overshoot from a low 0.65V input. The device features a typical peak input current limit of 1.5A. High efficiency is accomplished by integrating the low resistance N-Channel Boost switch and synchronous P-Channel switch. All compensation and protection circuitry are integrated to minimize external components. MCP1643 features an output overvoltage protection that limits the output voltage to 5.0V typical, in case the LED fails or output load is disconnected. MCP1643 is ideal for use in a variety of applications, including one- and two-cell Alkaline and NiMH/NiCd portable LED lighting products, LED flashlight and head lamps, rechargeable flashlights, wall LED lamps with motion detectors, and more.