A driver for driving a load unit includes a conversion circuit, a bypass circuit and control circuit. The conversion circuit is configured for converting an input voltage into an output voltage, in which the load unit is coupled to the conversion circuit to receive the output voltage and an output current. The bypass circuit is electrically coupled to the conversion circuit and the load unit. The control circuit controls the output current to flow through the load unit to drive the load unit in a driving mode. The control circuit controls the output current to flow through the bypass circuit in a standby mode, in which the output current in the standby mode is lower than the output current in the driving mode.