Patent ID: 8339117

Claim:
Electrical supply apparatus comprising: an output element; and a start-up circuit element coupled to the output element to ensure that the electrical supply apparatus reliably starts operation when first connected to a voltage of power supply rail, said start-up circuit element comprising first and second branches with current mirror coupling therebetween, said first branch comprising first and second transistors of opposite polarities coupled in series between the power supply rail and ground, and at least one leakage path coupled to the ground in parallel with said second transistor of said first branch to generate a start-up current through said first transistor of said first branch in response to an application of the voltage on the power supply rail, said second branch comprising a first transistor coupled between the power supply rail and a node connected to said output element, said current mirror coupling beteen said first and second branches to start up said first transistor of said second branch and to provide the start-up current through said node to the output element in response to the start-up current through said first transistor of said first branch, wherein said leakage path to ground comprises a P-N unction that is reverse biased in operation, and wherein a leakage current conduction area of said P-N junction in said leakage path to ground is greater than leakage current conduction areas of said first transistors.