| 摘要 |
PURPOSE:To compensate the variation in the environmental temperature by controlling the duty ratio of a drive pulse constant in response to the temperature change of a storage time of a switching element. CONSTITUTION:A DC voltage is converted by a switching element to pulse, rectified and smoothed to obtain the prescribed output voltage. Thus, the output voltage and a reference voltage are compared by a comparator 9 to obtain an error voltage, which is applied to a comparator 10. The output of a CR oscillator 7 for deciding the oscillating frequency by external resistor 7-1 and a capacitor 7-2 is converted to a triangular wave by a triangular wave generator 8 and applied to the comparator 10. A drive pulse varied in the width corresponding to the error voltage is obtained from the output of the comparator 10. In this case, a posistor having a temperature change corresponding to the temperature change of the storage time of a switching element is used as the resistor 7-1. Thus, even if the environmental temperature varies, the duty can be maintained constant. |
