Pololu 5V Step-Up Voltage Regulator U1V10F5 Overview This 5 V boost (step-up) voltage regulator generates higher output voltages from input voltages as low as 0.5 V, and it also automatically switches to a linear down-regulation mode when the input voltage exceeds the output. This makes it great for powering 5 V electronics projects from 1 to 3 NiMH, NiCd, or alkaline cells or from a single lithium-ion cell. When boosting, this module acts as a switching regulator (also called switched-mode power supplies (SMPS) or DC-to-DC converters) and has a typical efficiency between 70% to 90%. The available output current is a function of the input voltage, output voltage, and efficiency (see Typical Efficiency and Output Current section below), but the input current can typically be as high as 1.2 A. This regulator is also available with a fixed 3.3 V output, and very similar 3.3V, 5V, and adjustable-output versions are available with a true shutdown option that turns off power to the load. The regulators thermal shutdown engages at around 140C and helps prevent damage from overheating, but it does not have short-circuit or reverse-voltage protection. Features Input voltage: 0.5 V to 5.5 V Fixed 5 V output with 4% accuracy Automatic linear down-regulation when the input voltage is greater than the output voltage 1.2 A switch allows for input currents up to 1.2 AGood efficiency at light load: <1 mA typical no-load quiescent current, though it can exceed 1 mA for very low input voltages Integrated over-temperature shutoff Small size: 0.35 0.45 0.1 (9 11.5 2.5 mm) Using the Regulator Connections The boost regulator has three connections: input voltage (VIN), ground (GND), and output voltage (VOUT). The input voltage, VIN, must be at least 0.5 V for the regulator to turn on. However, once the regulator is on, the input voltage can drop as low as 0.3 V and the 5 V output voltage will be maintained on VOUT. Unlike standard boost regulators, this regulator has an additional linear down-regulation mode that allows it to convert input voltages as high as 5.5 V down to 5 V for small to moderate sized loads. When the input voltage exceeds 5 V, the regulator automatically switches to this down-regulation mode. The input voltage should not exceed 5.5 V. Please be wary of destructive LC spikes that might cause the input voltage to surpass 5.5 V (see below for more information). The three connections are labeled on the back side of the PCB, and they are arranged with a 0.1 spacing along the edge of the board for compatibility with solderless breadboards, connectors, and other prototyping arrangements that use a 0.1 grid. You can solder wires directly to the board or solder in either the 31 straight male header strip or the 31 right-angle male header strip that is included. Typical Efficiency and Output Current The efficiency of a voltage regulator, defined as (Power out)/(Power in), is an important measure of its performance, especially when battery life or heat are concerns. As shown in the graphs below, this switching regulator typically has an efficiency of 70 to 90%.