The LTC3401 is a high efficiency, fixed frequency, stepup DC/DC converter that operates from an input voltage below 1V. The device includes a 0.16 N-channel MOSFET switch and a 0.18 P-channel synchronous rectifier. Switching frequencies up to 3MHz are programmed with an external timing resistor and the oscillator can be synchronized to an external clock. An external Schottky diode is optional but will slightly improve efficiency.