AN1514

Off-line double output converters

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1

Off-line double output converters

In these circuits the first output is obtained using the standard buck or buck-boost topology,

while the second output is obtained by means of a second winding on the main inductor.

This output is directly coupled with the first one in flyback mode and its value is given by the

turns ratio n. The inductor is still low cost since a drum core can be used and the coupling

between the two windings is not as critical as in a flyback converter. The electrical

schematics of both configurations are shown in Figure 1 and Figure 2.

2

VIPer application examples

In this section two VIPerX2A-E application examples are introduced:

1.

Double output buck converter 24 V at 30 mA, 5 V at 50 mA

2.

Double output buck-boost converter (-24 V) at 250 mA, (-5 V) at 70 mA.

Figure 1.

Double output buck topology

Figure 2.

Double output buck-boost topology