Patent ID: 7652462

Claim:
A constant current regulator, comprising: a switch unit having a first terminal connected to an input voltage and a second terminal connected via an inductor to an output voltage; a gate driver circuit connected to a gate of the switch unit; a pulse width modulation controller connected to the gate driver circuit and having an error signal input terminal; a current sensing circuit loop connected to the switch unit to detect a current flowing through the switch unit and generate a detection current that is in proportion to the current flowing through the switch unit by a given ratio, the detection current being applied through a detection resistor to induce a detection voltage; and a differential amplifier having a set voltage input terminal, a detection voltage input terminal, and a differential signal output terminal, the set voltage input terminal being connected to a set voltage, the detection voltage input terminal being connected to the detection resistor to receive the detection voltage; wherein the differential amplifier bases on the set voltage and the received detection voltage to generate an error voltage at the differential signal output terminal thereof, the error voltage being applied to the pulse width modulation controller, which in turn causes the gate driver circuit to generate a switching control signal to control the switch unit, thereby supplying a constant current to a load connected to the output voltage.