Current limit protection circuit for a voltage regulator

A voltage regulator comprising:

• an output terminal;
• an error amplifier having an input connected to the output terminal, and an output providing a drive current;
• a power transistor connected to the output of said error amplifier for receiving the drive current;
• and
• a current limit protection circuit connected to said power transistor and comprising
• a first resistance connected to said power transistor for sensing an output current,
• a limit switch transistor connected to said power transistor and to said first resistance, and
• a current generator and second resistance connected thereto for biasing said limit switch transistor to divert drive current from said power transistor based upon the output current through said first resistance exceeding a threshold, and said first resistance having a value less than a value of said second resistance.

A voltage regulator comprising:

• an NPN bipolar power transistor receiving a drive current;
• and
• a current limit protection circuit connected to said NPN bipolar power transistor and comprising
• a first resistance connected to said NPN bipolar power transistor for sensing an output current,
• an NPN bipolar limit switch transistor connected to said NPN bipolar power transistor and to said first resistance,
• a current source and at least one NPN transistor connected thereto for generating a biasing current for biasing said NPN bipolar limit switch transistor, and
• a second resistance connected to said at least on NPN bipolar transistor and said first resistance so that biasing of said NPN bipolar limit switch transistor diverts drive current from said NPN bipolar power transistor based upon the output current through said first resistance exceeding a threshold.

A method for limiting output current from a voltage regulator comprising:

• providing a drive current to a power transistor connected to the voltage regulator;
• sensing the output current using a first resistance connected to the power transistor;
• generating a biasing current using a current generator and a second resistance connected thereto;
• and
• biasing a limit switch transistor connected to the power transistor and the first resistance with the biasing current for diverting the drive current from the power transistor based upon the output current through the first resistance exceeding a threshold.