The S7V7F5 switching step-up/step-down regulator efficiently produces 5 V from input voltages between 2.7 V and 11.8 V. Its ability to convert both higher and lower input voltages makes it useful for applications where the power supply voltage can vary greatly, as with batteries that start above but discharge below 5 V. The very compact (0.35″ × 0.475″) module has a typical efficiency of over 90% and can supply up to 1 A when stepping down and about 500 mA when stepping up.
The Pololu step-up/step-down voltage regulator S7V7F5 is a switching regulator (also called a switched-mode power supply (SMPS) or DC-to-DC converter) that uses a buck-boost topology. It takes an input voltage from 2.7 V to 11.8 V and increases or decreases the voltage to a fixed 5 V output with a typical efficiency of over 90%.
This flexibility in input voltage is especially well-suited for battery-powered applications in which the battery voltage begins above 5 V and drops below as the battery discharges. Without the typical restriction on the battery voltage staying above the required voltage throughout its life, new battery packs and form factors can be considered. For instance, a 4-cell battery holder, which might have a 6 V output with fresh alkalines but a 4.8 V nominal voltage with NiMH cells and a 4.0 V output with partially discharged cells, can now be used for a 5 V circuit. In another typical scenario, a disposable 9V battery powering a 5 V circuit can be discharged to under 3 V instead of cutting out at 6 V, as with typical linear or step-down regulators.
In typical applications, this regulator can deliver about 1 A continuous when the input voltage is higher than 5 V (stepping down) and 500 mA continuous when the input is lower than 5 V (stepping up); please see the graphs at the bottom of this page for a more detailed characterization. The regulator has short-circuit protection, and thermal shutdown prevents damage from overheating; the board does not have reverse-voltage protection.
More technical information at Pololu.