Application note for utilising optocouplers in flyback converters

Würth Elektronik has published its new Application Note, 'Compensating the feedback loop of a current-controlled flyback converter with optocoupler'. The guide is aimed at developers using a DC-DC flyback converter to accomplish greater stability and reliability in power supply design. It might also be useful for those who employ optocouplers for galvanic isolation of the feedback path. Applications include primary and auxiliary power supplies for home appliances, battery chargers for smartphones and tablets, and LED lighting. This Application Note also supplies valuable assistance with power supplies for desktop and laptop computers, industrial power supplies and auxiliary supplies in motor drives or for PoE.

AppNote ANP113 describes in detail how the feedback loop can be compensated by utilising a current-controlled flyback converter with an optocoupler and which aspects require special attention. The CTR influences the control loop of the compensation circuit and, therefore, must be carefully considered in the design stage. It places particular emphasis on design constraints imposed by the optocoupler parameters and on the related solutions. The validation results of a 30W flyback converter prototype are also included in the AppNote.