Patent ID: 7265529

Claim:
A start-up circuit, comprising: a current mirror; a start-up voltage reference coupled to a first output of the current mirror and to ground, the startup voltage reference comprising a plurality of coupled BJT transistors, a plurality of PN junction diodes, a plurality of Schottky diodes, a plurality of diodes, a plurality of diode connected metal oxide semiconductor (MOS) transistors, a plurality of diode connected field effect transistors (FET), a plurality of resistors, or a resistor voltage divider; and an output transistor coupled between a second output of the current mirror and an output of the start-up circuit, wherein an input of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference and where the output transistor is controlled by the voltage difference between a voltage output of the start-up voltage reference and a voltage of the output of the start-up circuit; wherein the start-up circuit is adapted to turn off when the voltage of the output of the start-up circuit is greater than the start-up voltage reference.