Flyback architecture for reduced low-power AC/DC losses

The new QuarEgg PSR (Primary Side Regulation) high-performance flyback solution significantly improves the efficiency and reduces the size of AC/DC converters that would traditionally have used active clamp flyback (ACF) and quasi-resonant (QR) topologies.

Built around Eggtronic’s patented and proven forced zero voltage switching (ZVS) architecture, QuarEgg PSR delivers a very flat idle-to-full-load efficiency curve ranging from 91% at low load to over 94.5% at maximum power. By using the architecture, designers can significantly reduce total operational losses when compared to conventional ACF and QR techniques. Target applications for QuarEgg PSR include routers, set-top-boxes, white goods and other low-power applications where efficiency and power density are key criteria but power factor correction (PFC) is not required.

At the heart of the new approach is Eggtronic’s EPIC QuarEgg PSR IC, a mixed-signal, low-power controller with multi-mode operation and synchronous rectification control that provides all the necessary primary side regulation without the need for an optocoupler. This highly integrated, miniature 5 x 5 mm device incorporates an optimised low-power mode for enhancing performance at zero and light loads and provides built-in protection against overvoltage, overcurrent, brownout and extreme temperatures.

“Designers of low-power applications are demanding ever-smaller, higher density power conversion architectures,” comments Igor Spinella, Eggtronic’s CEO and founder. “We developed the QuarEgg forced ZVS concept to address these demands by providing engineers with a solution that enables high-efficiency low- to high-load operation while reducing overall component count. In our first iteration we created a PD concept that eliminated the need for a high-voltage, high-side clamping MOSFET, and now we have extended this concept to fixed-voltage solutions that allow us to place an EPIC controller on the primary side and further drive down BoM.”