Electronic device incorporating system power supply unit and method for supplying power supply voltage

A power supply unit for use with a system unit including a load to supply an operational voltage to the load, the system unit including a memory circuit storing a set value for setting the operational voltage, and a first communication circuit adapted to read the set value from the memory circuit to transmit the set value to the power supply unit after an initial operational voltage is supplied, the power supply unit comprising:

• a second voltage generation circuit adapted to supply the memory circuit and the first communication circuit with the initial operational voltage for operating the memory circuit and the first communication circuit:
• a second communication circuit adapted to receive the set value from the first communication circuit;
• and
• a first voltage generation circuit adapted to supply the system unit with a voltage corresponding to the set value as the operational voltage.

A method for supplying an operational voltage from a power supply unit to a load of a system unit connected to the power supply unit, the method comprising:

• storing a set value for setting an operational voltage in a memory circuit of the system unit;
• supplying from a second voltage generation circuit of the power supply unit to the memory circuit and a first communication circuit of the system unit with an initial operational voltage for operating the memory circuit and the first communication circuit;
• reading the set value stored in the memory circuit to transmit the set value via the first communication circuit to a second communication circuit of the power supply unit;
• receiving the set value at the second communication circuit of the power supply unit;
• supplying a voltage corresponding to the set value as the operational voltage from the power supply unit;
• and
• decreasing supply of the initial voltage to the memory circuit and the first communication circuit of the system unit after the power supply unit receives the set value from the system unit.