| 摘要 |
PURPOSE:To prevent the generation of surge currents by linearly fluctuating the reference voltage used for an error amplifier circuit in response to an ambient temperature. CONSTITUTION:The output voltage Vout of a variable resistance means 10 is used as power for driving a motor fan. A proportional-signal generating means 50 fluctuates the reference voltage in direct proportion to a temperature Ta on the basis of the temperature Ta detected by the detecting means 40 of the ambient temperature in the vicinity of an object to be cooled. Regarding a signal clamping circuit 60, the voltage determined by the minimum voltage required for driving the motor fan is used as the reference voltage when the output voltage of the proportional-signal generating means 50 is lower than the first reference voltage Vth1, and the voltage determined by the maximum voltage permitted for driving the motor fan is employed as the reference voltage when the output voltage is higher than the second reference voltage Vth2. An error amplifier circuit 30 compares the output voltage Vout of the variable resistance means 10 and reference voltage, and transmits a control signal over the variable resistance means 10 in the direction that the error is reduced. |
