The invention relates to a voltage regulator for the alternator of an automobile, comprising electronic adjustment circuits (10) and means for generating a signal representative of an excitation current supplied to an excitation coil of the alternator. According to the invention, the regulator includes a programmable signal processing interface (11) that receives at the input at least one signal (SS; Sp, SGp, Sexc) representative of the excitation current and supplies at the output a processed signal (Srex) transmitted to an electronic control interface (3) of the vehicle. The interface (11) includes means (111) for applying different forms of processing to the representative signals (SS; Sp, SGp, Sexc) and means (MU130 to MU133) for selecting, based on a programming word (M) a form of processing to be applied to said signal. Typically, the representative signal is a PWM signal.