Patent ID: 8184419

Claim:
A method for a current limiting function in a power supply, comprising; providing a first current limiting circuit which comprises: a resistor, a PWM control, a MOSFET, a shunt regulator, and a first transistor and further comprising, providing a second current limiting circuit on the secondary side of a transformer, located within the power supply, using a PCB copper trace as a current sensing element, further comprising the steps of: (a) providing a resistor, a zener diode, and operational amplifiers; (b) sensing a voltage from said PCB copper trace; (c) comparing said voltage sensed with voltage developed from said zener diode; (d) providing a second shunt regulator and an opto-coupler comprising a primary LED and a secondary transistor; and (e) causing the power supply to initiate a shut down sequence when the output of said operational amplifiers increases to a high level thereby causing said secondary transistor to turn on fully and forcing current flow through said opto-coupler causing said PWM control to stop the gate drive to said MOSFET resulting in the shut down of the power supply to a latch-off condition.