Linear power regulator with current limiting and thermal shutdown and recycle

Claim 1

A power supply having an input terminal and an output terminal for connection between an input voltage source and a load to provide an output voltage and an output current to the load, said power supply comprising: (a) a MOSFET having a source, a gate and a drain, said source and drain being arranged for connection between the input voltage source and the load; (b) means connected to said gate of said MOSFET for applying a bias voltage at least equal to the desired output voltage to said gate of said MOSFET to place said MOSFET in a conductive state; (c) means connected to said bias voltage applying means for providing a reference voltage; and (d) difference amplifier means, connected to said drain and gate of said MOSFET, to said reference voltage providing means, and to said output terminal, for maintaining a fixed ratio between said reference voltage and the output voltage, said difference amplifier means including (i) first and second amplifiers each having first and second terminals and a base, (ii) a first resistor connected between said output terminal and said base of said first amplifier, (iii) a second resistor connected between a ground and said base of said first amplifier, (iv) said first amplifier at said first terminal being connected to said gate of said MOSFET, (v) a third resistor connected between a ground and said second terminals of said respective first and second amplifiers, (vi) said second amplifier at said first terminal being connected to said drain of said MOSFET, and (vii) said second amplifier at said base being connected to said reference voltage providing means such that said difference amplifier means controls the output voltage by maintaining the voltage at said base of said second amplifier substantially equal to the voltage at said base of said first amplifier.