Figure 13. Constant output voltage control principle: internal schematic and pin configuration

Figure 14. Burst-mode operation

5.6

Line voltage feed-forward block

The power that a QR flyback converter with a fixed overcurrent set point can deliver changes considerably with

the input voltage.

In wide-range mains applications, the deliverable power at high line can be more than twice than at minimum

voltage. This is a problem because it means that at high line the system could be operated at a power level much

higher than that which triggers overload at low lines, thus requiring an overrating of the power components.

The VIPERGAN50 implement a feed-forward function able to solve this issue: the voltage across the auxiliary

winding is monitored and the information is used to compensate the converter (see Figure 15).

VIPERGAN50

Line voltage feed-forward block

DS13888 - Rev 2

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