A power supply device (200; 200A; 200B) for supplying power to an electrical load system, the power supply device (200; 200A; 200B) comprising at least: - a first power supply, the first power supply providing a first input voltage; - a second power supply, the second power supply providing a second input voltage, the second input voltage being lower than the first voltage; - a third power supply, the third power supply providing a third input voltage, the third input voltage being lower than the second input voltage; - a first input, the first input being electrically connected to the first power supply; - a second input, the second input being electrically connected to the second power supply; - a third input, the third input being electrically connected to the third power supply; - a first output, the first output being electrically connected, on the one hand, to the first input and, on the other hand, to the second input, the first output being configured to electrically supply a first part of the electrical load system with a first output voltage (VOUT1) supplied by the first input or by the second input; - a protection diode (D4, D5), the protection diode (D4, D5) being electrically connected on the one hand to the first input and on the other hand to the second input; - a second output, the second output being configured to electrically supply a second part of the electrical load system with a second output voltage (VOUT2), the second output voltage (VOUT2) being lower than the third input voltage; - a first voltage regulator, an input (U1_IN) of the first voltage regulator being connected to the second input, the third input being electrically connected to an output (U1_OUT) of the first voltage regulator, and - a second voltage regulator, an input (U2_OUT) of the second voltage regulator being electrically connected to the output (U1_OUT) of the first voltage regulator, an output (U2_OUT) of the second voltage regulator being electrically connected to the second output in order to supply electrical power to the second part of the electrical load system. - a first power supply, the first power supply providing a first input voltage; - a second power supply, the second power supply providing a second input voltage, the second input voltage being lower than the first voltage; - a third power supply, the third power supply providing a third input voltage, the third input voltage being lower than the second input voltage; - a first input, the first input being electrically connected to the first power supply; - a second input, the second input being electrically connected to the second power supply; - a third input, the third input being electrically connected to the third power supply; - a first output, the first output being electrically connected, on the one hand, to the first input and, on the other hand, to the second input, the first output being configured to electrically supply a first part of the electrical load system with a first output voltage (VOUT1) supplied by the first input or by the second input; - a protection diode (D4, D5), the protection diode (D4, D5) being electrically connected on the one hand to the first input and on the other hand to the second input; - a second output, the second output being configured to electrically supply a second part of the electrical load system with a second output voltage (VOUT2), the second output voltage (VOUT2) being lower than the third input voltage; - a first voltage regulator, an input (U1_IN) of the first voltage regulator being connected to the second input, the third input being electrically connected to an output (U1_OUT) of the first voltage regulator, and - a second voltage regulator, an input (U2_OUT) of the second voltage regulator being electrically connected to the output (U1_OUT) of the first voltage regulator, an output (U2_OUT) of the second voltage regulator being electrically connected to the second output in order to supply electrical power to the second part of the electrical load system.