Abstract: Increasing strong demand for smaller insulated transformers, an ultra-small transformer has been developed by adopting an insulated hybrid structure with the size of W16.5 x L19.5 x H10.5 mm^3, whose volume is 65 % smaller than conventional insulated transformers. Our new transformer has been improved in terms of noise reduction by 5-15 dB, power efficiency increase by 2 %, and production efficiency by 50 %. Relevant analyses are to be given.

Keywords: AC Adapter, Insulated transformer, Hybrid structure, Small size.