Implementation aspects of a new linear regulator topology based on low frequency supercapacitor circulation

Abstract

Point of load (POL) powering concepts are used in modern portable products where low dropout regulators (LDO) are mixed with switching regulators. However, LDOs are efficient only when the input to output differential voltage is small. When the input to output differential voltage is large, this efficiency limitation can be overcome by applying a supercapacitor circulation technique at the input side of the LDO. With the commercial LDOs available with output current ratings up to 10A, and, thin profile supercapacitors with DC voltage ratings from 2.3V to 5.5V, this patented technique can be easily configured for common DC-DC converters such as 12 to 5V, 5 to 3.3V and 5 to 1.5V. This novel topology helps increasing the end-to-end efficiency of LDO based linear converters closer to the efficiency benchmarks of modern switch mode power supplies, maintaining the superior output specifications of a linear regulator. Paper provides practical implementation details of different cases discussing the important design aspects, and how this novel topology could assist increasing the end-to-end efficiency of a linear regulator, with a view to get the best out of linear regulator based DC-DC converters.