Some electronic applications require an isolated auxiliary power supply that must be generated from a low-voltage AC adapter. Examples of such applications include isolated MOSFET drive circuits and relay controls. Finding an isolated power-supply controller that will operate at such low voltages can prove difficult. Fortunately, it is possible to configure some low-power boost converters, such as the Texas Instruments (TI) TPS61175, to operate and control a flyback power stage. This article explains how to use the TPS61175 in an isolated flyback application.