Generate dual supply rails using a high-efficiency SEPIC-Cuk converter

摘要

Even with the eidespread use of single-supply rail-to-rail op amps, dual rails (for example, ±15 V) must often be generated from a single (positive) input rail to power other parts of the analog signal chain. These are often low current (such as 10 mA to 500 mA), with relatively well-matched loads on the positive and negative supplies. One solution to this problem is to use two different dc-to-dc converters; one to provide the positive rail and one to provide the negative rail. This can be expensive and, as this article shows, unnecessary. Another solution uses a flyback, but the supplies don't track each other very well with differential loading, a large, expensive transformer is required, and efficiency tends to be low.