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Fairchild Semiconductor's Resonant Controller Simplifies Power Design for Applications up to 600W


Highly Integrated Approach Reduces Components and Bill of Materials

Fairchild Semiconductor brings power designers of LCD and PDP TVs, servers, game consoles and LED lighting applications the FAN7621. This resonant controller simplifies design, reduces bill of materials and provides advanced protection functions. The FAN7621 integrates a high-side gate-drive circuit, a current-controlled oscillator, frequency- limit circuit, soft start and numerous protection functions in a 16-pin SOP/DIP package. This highly integrated device eliminates the need for expensive external circuitry such as pulse transformers to conserve not only board space but to reduce the cost of the overall design. The FAN7621’s internal high side gate-drive circuit offers an added benefit of common-mode noise cancellation, ensuring excellent noise immunity, enabling the application to meet stringent EMI specifications. For further noise immunity, the FAN7621 offers designers a zero voltage switching (ZVS) technique that reduces switching noise and allows the use of a smaller and less expensive EMI filter.

The FAN7621 is designed with robust protection features such as over voltage protection (OVP), over current protection (OCP), abnormal over current protection (AOCP) and internal thermal shutdown. Other solutions require additional components to achieve the same level of protection, which adds to design time and overall system costs.

The FAN7621’s ZVS technique dramatically reduces switching losses in MOSFETs and rectifiers. Compared to conventional hard-switching converter topologies, efficiency is improved by 10 percent and for applications such as PDP-TVs, efficiency reaches 97 percent. An added advantage of this ZVS technique is the dramatic reduction in switching noise – at least 5dB – compared to hard-switching techniques.