Supercapacitor assisted LDO (SCALDO) techniquean extra low frequency design approach to high efficiency DC-DC converters and how it compares with the classical switched capacitor converters

Supercapacitor assisted low dropout regulators (SCALDO) were proposed as an alternative design approach to DC-DC converters, where the supercapacitor circulation frequency (switching frequency) is in the order of few Hz to few 10s of Hz, with an output stage based on a low dropout regulator stage. For converters such as 12–5V, 5–3.3V and 5–1.5V, the technique provides efficiency improvement factors of 2, 1.33 and 3 respectively, in compared to linear converters with same input-output combinations. In a 5–1.5V SCALDO regulator, using thin profile supercapacitors in the range of fractional farads to few farads, this translates to an approximate end to end efficiency of near 90%. However, there were concerns that this patented technique is merely a variation of well-known switched capacitor (charge pump) converters. This paper is aimed at providing a broad overview of the capability of SCALDO technique with generalized theory, indicating its capabilities and limitations, and comparing the practical performance with a typical switched capacitor converter of similar current capability

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

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

A low frequency supercapacitor circulation technique to improve the efficiency of linear regulators based on LDO ICs

Linear regulators have output specifications far superior to switch-mode techniques, except for the overall efficiency. This efficiency limitation can be overcome by applying a very low frequency supercapacitor circulation technique at the input side of a low dropout regulator IC. The technique was proven in 12V to 5 V versions, and, can be easily applied to other power supplies such as 5 to 3.3V or 5 to 1.5V versions required by various processors. The paper outlines the concepts and experimental results related to this technique. With the commercial LDO chips available with output current ratings up to 10A, and, thin profile supercapacitors available are with DC voltage ratings from 2.3V to 5.5V, the technique assists developing medium current linear regulators which could compete with present day switch-mode power supplies in efficiency and compactness, maintaining the superior output specifications of a linear regulator

Very low frequency supercapacitor techniques to improve the end-to-end efficiency of DC-DC converters based on commercial off the shelf LDOs

Given the advantages of linear regulator techniques, low dropout regulator ICs are frequently used in portable consumer electronics. Only disadvantage in linear regulators, low efficiency, can be overcome by a very low frequency supercapacitor energy recovery technique to achieve efficiencies similar to common switching regulator techniques. This technique was successfully applied in a 12 V to 5 V regulator. The article provides some generalized theoretical background and different supercapacitor circulating options which can be applied to different cases of linear regulators

Laplace transform-based theoretical foundations and experimental validation: low-frequency supercapacitor circulation for efficiency improvements in linear regulators

Supercapacitor circulation techniques can be used to improve the end-to-end efficiency of linear regulators based on commercial low drop-out regulators (LDO). In this approach, one or more supercapacitors are used in series and parallel to the input of an LDO IC, and circulated at a very low frequency to increase the end-to-end efficiency by a multiplication factor compared with the efficiency of a linear regulator circuit with the same input–output voltages. This study presents the essential theory of supercapacitor circulation, together with analytical results and comparisons with experimental measurements from a practical 12–5 V implementation. The new technique achieved overall end-to-end efficiencies in the range of 70 to 80%, compared with the maximum theoretical efficiency of 42% for a 12–5 V linear regulator