Patent ID: 8022686

Claim:
An apparatus comprising: a reference circuit that is adapted to provide a startup current; a startup circuit that receives the startup current and outputs an output voltage, wherein the startup circuit includes: a current mirror; a first transistor having a first passive electrode, a second passive electrode, and a control electrode, wherein the first passive electrode of the first transistor is coupled to the current mirror, and wherein the control electrode of the first transistor is coupled to the reference circuit; a second transistor having a first passive electrode, a second passive electrode, and a control electrode, wherein the first passive electrode of the second transistor is coupled to the current mirror, and wherein the control electrode of the second transistor is coupled to the reference circuit and to the control electrode of the first transistor; a plurality of diodes coupled between the control electrode of the second transistor and the first passive electrode of the second transistor; a third transistor having a first passive electrode, a second passive electrode, and a control electrode, wherein the control electrode of the third transistor is coupled to the first passive electrode of the second transistor, and wherein the output voltage is provided from the second passive electrode of the third transistor; and a control circuit that is coupled to the second passive electrodes of the first and second transistors.