| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable output device which can output 0 V stably even if it is arranged on the primary side of a switching transformer, and is free of breaking at transition of input. SOLUTION: In this variable output device consisting of a DC-DC converter 2 and a fan control IC 3 for controlling the output voltage of the DC-DC voltage based on a control signal, a pull-up resistor 5 is provided between the drive power source Vcc for the fan control IC3 and the non-inversion input terminal of an error amplifier 4 where the voltage divided by resistor form the output voltage of the DC-DC converter 2 is inputted in the above fan control IC equipped with the error amplifier 4 constituted of an operational amplifier, and the voltage of the non-inversion input terminal in the error amplifier 4 is set higher at all times than the voltage of the non-inversion input terminal where the above control signal is inputted, when the control signal is 0 V or outside the control voltage region. |
