Improving the End-to-End Efficiency of DC-DC Converters Based on a Supercapacitor-Assisted Low-Dropout Regulator Technique

Approximate efficiency of a linear regulator, if the power consumed by the control circuits is negligible, can be expressed by the ratio of Vo/Vin. A very low frequency supercapacitor circulation technique can be combined with commercial low-dropout (LDO) regulator integrated circuits to achieve significantly high end-to-end efficiency, and the result could be closer to the efficiencies of practical switching regulators. In this technique, supercapacitors are used as lossless voltage droppers, and the energy reuse occurs at very low frequencies such as from few hertz to few hundred hertz only, eliminating any radio-frequency interference/electromagnetic interference issues, compared to the switching regulators which utilize bulky inductors. Also, the technique is not a variation of charge pump converters due to nine clear reasons. Fundamental concepts related to this supercapacitor-assisted LDO regulator technique are discussed with experimental details of 12-5 V and 5-3.3 V versions together with a discussion on fundamental secondary losses associated with this novel technique.