The power supply device comprises a supply transistor commanded by a command signal and providing electric power to a lighting module, and a driving means configured to selectively generate, depending on an instruction signal representative of the structure of said at least one lighting module, a first command signal able to command the supply transistor into an ohmic regime, a second command signal able to command the supply transistor into a pulse width modulation regime involving an alternation of ohmic regimes and blocked regimes, and a third command signal able to command the supply transistor into a saturated regime.