Zero bridge loss design enhances thermal efficiency

The company claims that they virtually eliminate the bridge rectifier losses in AC/DC power supplies and adapters, to increase efficiency and thermal performance in products and power supplies, particularly in data centres. They are used for high power - 100W and above - adapters used for high-end laptops and televisions as well as power supplies for desktops, game consoles, servers, and telecomms.

Initial family members are the AOZ7200 controller and the AOZ7270. The controller is in a SOT-23 package while the AOZ7270 integrates a 600V, 190mΩ MOSFET in a DFN 5.0 x 7.0mm package. The AOZ7200 can be paired with the company’s super junction MOSFETs to optimise performance and cost, while the AOZ7270 reduces component count and design time. Both products are self-powered from the AC line and do not require external circuitry.

The proprietary self-biasing scheme takes minimal power from the AC line making it very efficient in light load or standby mode of operation. In a typical 100W application, the AOZ7270DI delivers efficiency improvements of 0.89% at 115V AC and 0.44% at 230V AC over a diode bridge. Both products exceed lightning surge requirements for AC/DC applications.

“Today’s data centres strive for improved efficiency and thermals,” said Colin Huang, Power IC Marketing Manager at Alpha and Omega Semiconductor. A condundrum faced by power system designers is that cooling the data centre can take as much - if not more power - than the servers themselves, said Huang, explaining the need for thermal performance. The AlphaZBL products can be used in power supplies to achieve Titanium-grade efficiency, Huang advised. In addition, high power adapters face thermal challenges as power density increases. “Active bridge rectification enabled by AOZ7200 and AOZ7270 offer the simplest path to reducing power losses,” said Huang.

The AOZ72xx series is now available in production quantities and with a lead-time of 12 weeks.