Resonant Discontinuous Forward Converter (RDFC) is a novel topology delivering considerable technical and commercial benefits when coupled with CamSemi’s C2470 family of mixed signal controllers.

Advantages include:

• Low cost components, small transformers and simple designs covering a wide power range
• Very high efficiency
• Low standby power
• Soft-switching resonant waveforms
• Easy compliance with EMI regulations – even at high power levels
• Safety features from both the topology and the controller
• Small footprint transformers to reduce the demand for copper, steel and other raw materials consumed during manufacturing

RDFC is aimed primarily at linear replacement in a wide variety of applications such as plug-top adapters, embedded supplies and battery chargers and enables easy, fast compliance with the most demanding energy-efficiency and EMI regulations.  Even at higher power levels, this innovative approach achieves the required EMI regulations with significant margin and without needing expensive, bulky common mode filter components.

Ultra low EMI for AM radios
The majority of today’s hard switching SMPS topologies create EMI that interferes with the AM band radio function, but CamSemi’s unique soft switching resonant waveform approach makes it ideal for audio and other EMI-sensitive applications.  RDFC enables designs that achieve very low EMI of >30 dB quasi-peak margin on conducted emissions to EN550022.

For example: AD-2080 is a highly cost-effective 20 W average (40 W peak) supply for powering audio equipment that contains an AM radio.  The conducted EMI for this design, using simple screening and two low-cost filter components is so low that it cannot even be measured effectively using a commercial EMI set up.