The invention relates to a control and power module for an alternator-starter for a motor vehicle, connected between the alternator-starter (3), an on-board wiring network (Ua) and a ground line (GND) of the vehicle, and comprising: a transistor bridge with several branches (B1 B3), and a control unit for comparing a phase voltage (.psi.) of the machine with a reference voltage (Ua, GND) and for controlling the transistors as a function of the result of the comparison, the control unit comprising: a driver (10, 20, 30) for each branch of the transistor bridge, the driver being connected close to the transistors of the branch, and a control circuit for controlling the drivers.