DC-DC converter chips provide a regulated DC voltage output from a different, unregulated input voltage. They are used in power management applications and incorporate several conversion technologies. Buck or step-down converters convert a higher DC input voltage to a lower DC output voltage of the same polarity. Using a transistor as a switch, buck converters alternately connect and disconnect the input voltage to an inductor. Boost or step-up converters convert a lower DC input voltage to a higher DC output voltage of the same polarity. Buck-boost converters can be used for either step-up or step-down conversions, and to reverse or invert voltage polarity. CUK converters use capacitive energy transfers, creating a smooth current at both sides of the converter. Charge pump converters are suitable for voltage step-up or voltage inversion in low power applications. Unlike most other DC-DC converter chips, charge pumps store energy in a capacitor instead of an inductor. Flyback converters are similar to buck-boost converters, but use a transformer to store energy and provide isolation between the input and output. These devices have two distinct phases for energy storage and delivery. Forward converters are similar to flyback converters, but use transformers in a more traditional manner, transferring energy from input to output in a single step.