Patent ID: 7848119

Claim:
A direct current (DC) to DC converter comprising: a transistor comprising a gate electrode, a drain electrode, and a source electrode; a first rectifying and filtering circuit configured for transforming an external alternating current (AC) voltage to a first DC voltage; a transformer comprising a primary winding, an assistant winding connected with the primary winding in a flyback mode, and a secondary winding, the first DC voltage being connected to ground via the primary winding, the drain electrode and the source electrode of the transistor in series; a pulse generating circuit comprising a controlling terminal, a diode, a resistor, and a capacitor, one terminal of the assistant winding being connected to ground, the other terminal of the assistant winding being connected to the anode of the diode, the cathode of the diode being connected to ground via the resistor and the capacitor in series, a node between the resistor and the capacitor being defined as the control terminal and being connected to the gate electrode of the transistor; and a zener diode connected between the capacitor and ground, the anode of the zener diode being connected to ground.