Patent ID: 7365996
Filing Date: 2008-04-29
Classification: H02M

Abstract:
1. A switched-mode power supply for converting a DC input voltage into an output voltage having a trigger circuit for triggering at least one controlled switch that periodically applies the input voltage to at least one primary winding of a transformer, it being possible to switch off an auxiliary voltage for the trigger circuit using an auxiliary semiconductor switch when the input voltage drops below a given minimum value, the auxiliary voltage being, on the one hand, a first auxiliary supply voltage derived from the input voltage and, on the other hand, a second auxiliary supply voltage derived from an auxiliary winding of the transformer via rectification wherein the gate electrode of the auxiliary switch is connected on the one hand with a reference voltage output of a reference voltage produced internally in the trigger circuit and on the other hand with a divider point of an input voltage divider, so when the trigger circuit is operative the gate electrode of the auxiliary switch receives an additional voltage in the sense of a forced tripping of the auxiliary switch.