The goal of this paper is to present a design example of a 5.0 W rated AC−DC adapter for consumer products like the mobile phone, walkman, walkie−talkie, MPEG players, digital camera, various battery chargers, etc. This sort of adapter is specified at very low cost to not hamper the selling price of the above products. However, this does not imply that an adapter designer has to sacrifice safety, precision and standby performance.