Guía Técnica


> Back

2.4. Forward

The forward converter (fig. 9) has an operation principle similar to the one of the buck converter, although, additionally, it is equipped with a transformer. This change allows having an output voltage higher than the input voltage by using an appropriate transformation ratio and, also, it provides electric isolation between input and output. While Q is on, current flows in the secondary through D1, with a waveform identical to the IQ signal in the buck converter. While Q is not on, diode D2 lets the current flow through coil L, in a similar manner to the version without isolation. This diode D2 is called freewheel diode because, together with L, it behaves as a flywheel for the current. The third winding appearing in the figure allows the transformer to be demagnetized through D3 while Q is not on. As in all topologies equipped with a transformer, by adding other windings multiple outputs can be obtained.