Controller supports both Fixed-Frequency and quasi-resonant modes

Geneva—STMicroelectronics announced a flexible and cost-saving controller for high-performance flyback power converters, which can operate in either the FixedFrequency (FF) or the Quasi-Resonant (QR) mode—the two principal operating modes used in flyback SMPS—selectable by connection of a single pin.

According to ST, this design enables manufacturers to stock and qualify a single component to meet the requirements of different applications.

The chip integrates many protection capabilities commonly implemented with external components, and energy-saving features that help the designer to meet the most severe energy regulations.

The L6566 selectable multi-mode controller is suitable in applications such
as flyback AC/DC adapters, TV and LCD monitors, small size LCD TVs, high end chargers, and in other consumer equipment such as DVD players and set-top boxes.

Under very light load conditions, in both operating modes, the chip enters a
controlled burst-mode state at low frequency (a few hundred Hertz) with
constant peak current, in order to minimize total power requirements and to
comply with world-wide energy saving recommendations. The controller provides quiescent current (less than 3mA) and on-board non-dissipative start-up

The IC is available in two orderable versions, L6566A and L6566B. The L6566A is designed specifically for converters supplied through a front-end Power Factor Corrector (PFC) circuit; it provides an interface to the PFC to turn off the regulator under light or no-load conditions and during all the fault conditions. The L6566B version is intended for applications where a
front-end PFC is not used, and it includes an oscillator frequency
modulation input to reduce EMI (electromagnetic interference) emissions,
saving cost and size of the line filter when FF operation is selected.

Pricing: $0.50 in quantities of 2500 pieces.
Availability: In volume now, in an SO-16 package.
Datasheets: L6566A and L6566B.

STMicroelectronics Inc., 1-781-861-2650,

0 comments on “Controller supports both Fixed-Frequency and quasi-resonant modes

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.