The MCP1665 device is a compact, high-efficiency, fixed-frequency, non-synchronous step-up DC-DC converter that integrates a 36V, 100 mΩ NMOS switch. It provides a space-efficient high-voltage step-up power supply solution for applications powered by either three-cell alkaline, Ultimate Lithium, NiCd, NiMH, one-cell Li-Ion or Li-Polymer batteries. The integrated switch is protected by the typical 3.6A cycle-by-cycle inductor peak current limit operation. There is an output overvoltage protection and an open-load protection that turn off switching if the feedback resistors are accidentally disconnected, the feedback pin is short-circuited to GND or the output is exposed to excessive voltage. Pulse-Frequency Modulation (PFM) switching mode used for power saving is implemented, and it is selectable by the dedicated MODE pin. MCP1665 is easy to use and allows creating classic boost, SEPIC or flyback DC-DC converters within a small Printed Circuit Board (PCB) area. All compensation and protection circuitry are integrated to minimize the number of external components.