Patent ID: 7813149

Claim:
A power supply device comprising: a diode bridge including a first terminal coupled to a first voltage reference, a second terminal coupled to a second voltage reference, a third terminal, and a fourth terminal; a transformer including a primary winding having a first terminal coupled to the third terminal of the diode bridge and a second terminal; a transistor including a first current electrode coupled to the second terminal of the primary winding of the transformer, a second current electrode coupled to the fourth terminal of the diode bridge, and a control electrode; and a digital control module including a first input terminal coupled to the third terminal of the diode bridge, and an output terminal coupled to the control electrode of the transistor, the control module adapted to prevent a potential saturation of the transformer by setting a maximum allowable duty cycle and a switching frequency for a control signal transmitted to the transistor, based on an input voltage, the digital control module decreasing the maximum allowable duty cycle in response to a high input voltage level.