The DC-DC converter is a voltage converter that effectively outputs a fixed voltage after converting the input voltage. DC to DC converters are divided into three categories: step up DC-DC converters, step down DC- DC converters, and buck-boost DC-DC converters. Three types of controls can be used according to requirements. At present, DC to DC converters are widely used in products such as mobile phones, MP3s, digital cameras, and portable media players.