DRIVE CIRCUIT OF A MOTOR VEHICLE ALTERNATOR, VOLTAGE REGULATOR AND ALTERNATOR INCLUDING SAME

The excitation circuit according to the invention controls an excitation current (lexc) in an excitation winding (2) of an alternator by means of a control loop of an on-board network voltage (Vbat+, 3) of the vehicle, and comprises a first MOS power transistor (9) connected between a first positive supply terminal Vbat+ (6) and a first excitation terminal (7) and controlled by the control loop by means of a first control circuit (10), and a second MOS power transistor (11) connected between the first excitation terminal and a second excitation terminal (8) connected to a ground terminal (5) and functioning as a freewheel diode by being controlled by means of a second control circuit (12). In accordance with the invention, the circuit further comprises a servo loop (15) of a drain-source voltage (Vds) of the second transistor.