| 摘要 |
PURPOSE: To reduce the power loss of a final stage by reducing a power supply voltage supplied to a driving circuit to an optimum value. CONSTITUTION: This circuit is provided with a driving part 14 for generating a voltage proportional to an input voltage Vin and driving a load, the switching down part 16 of a power source circuit for supplying power to the power source of the active element 3 for voltage control of the final stage of the driving part 14 and a PWM control part 15 for controlling the power source circuit of the switching down part 16 so as to turn the power supply voltage supplied to the driving circuit of the driving part 14 to a minimum voltage within a range in which an output voltage Vout supplied to the load 5 is not saturated corresponding to the input voltage Vin. |
