The TinySwitch family uses a breakthrough design to provide the lowest cost, high efficiency, off-line switcher solution in the 0 to 10 W range. These devices integrate a 700 V power MOSFET, oscillator, high voltage switched current source, current limit and thermal shutdown circuitry. They start-up and run on power derived from the DRAIN voltage, eliminating the need for a transformer bias winding and the associated circuitry. And yet, they consume only about 80 mW at no load, from 265VAC input. A simple ON/OFF control scheme also eliminates the need for loop compensation.
The TNY255 uses a switching rate of 130kHz to deliver up to 10 W from the same low cost EE16 core for applications such as PC standby supply. An EE13 or EF13 core with safety spaced bobbin can be used for applications under 2.5W. Absence of a bias winding eliminates the need for taping/margins in most applications, when triple insulated wire is used for the secondary. This simplifies the transformer construction and reduces cost.
