Micrel’s MIC2571 is a micropower boost switching regulator that operates from one alkaline, nickel-metal-hydride cell, or lithium cell. The MIC2571 accepts a positive input voltage between 0.9V and 15V. Its typical no-load supply current is 120μA. The MIC2571 is available in selectable fixed output or adjust- able output versions. The MIC2571-1 can be configured for 2.85V, 3.3V, or 5V by connecting one of three separate feedback pins to the output. The MIC2571-2 can be config- ured for an output voltage ranging between its input voltage and 36V, using an external resistor network. The MIC2571 has a fixed switching frequency of 20kHz. An external SYNC connection allows the switching frequency to be synchronized to an external signal. The MIC2571 requires only four components (diode, induc- tor, input capacitor and output capacitor) to implement a boost regulator. A complete regulator can be constructed in a 0.3 in2 area. All versions are available in an 8-lead MSOP with an operat- ing range from –40°C to +85°.