Power Electronics

Self-Contained Synchronous Rectifier for Power Switching Applications

ON Semiconductor has introduced a self-contained synchronous rectifier that helps designers achieve higher power density in switching power supply designs that previously required discrete solutions. This chip is a member of the Better Efficiency Rectification System (BERS) family of devices.

“Achieving acceptable efficiency levels in today’s demanding synchronous rectification designs is hard work,” said Sue Nee, ON Semiconductor product marketing manager for Application Specific Products. “Typical designs require many discrete components and usually an extended design time to get the system just right. With the introduction of the NIS6111, designers can overcome these hurdles quickly and easily. The simplicity and flexibility of the NIS6111 allows it to be dropped into existing power supply designs with only minor layout changes.”

The patented NIS6111 is a high-speed, high-efficiency hybrid rectifier that couples a high-speed comparator and MOSFET driver with a power MOSFET to create a diode with the same forward-drop characteristics as a MOSFET. The low forward drop and fast switching of the NIS6111 improve efficiency and eliminate bulky heat sinks by lowering junction temperatures for secondary rectification in flyback or resonant topology switching power supplies. Furthermore, because it does not have to be ground referenced, it can easily be used as a simple, two terminal replacement for lossy rectifiers in switching power supplies.

The NIS6111 is capable of blocking up to 24 V and has a typical forward voltage drop of 0.1 V at a forward current of 20 A. Versions that offer 60-V and 100-V blocking will be added to the BERS family later in 2005.

In addition to switching power supply designs, the NIS6111 will do equally well as an ORing diode. It provides a solution much less susceptible to pc board layout problems, such as oscillations or slower fault recovery speeds, than a discrete ORing controller and MOSFET. Also, additional MOSFETs can be added to the NIS6111 to increase its power handling capability.

The NIS6111 is offered in a 9-mm × 9-mm QFN package and is priced at is $2.99 per unit in 10,000-unit quantities.

For more information, visit www.onsemi.com.

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