| 摘要 |
PURPOSE:To obtain a constant voltage power source by a DC/DC converter of good temperature characteristic, by making constant the output voltage of a rectification circuit on the secondary side as viewed from the primary side of low potential regardless of the output voltage on the secondary side and by letting the impressing voltage to a detection circuit the value without temperature dependency. CONSTITUTION:A self-oscillation circuit is composed of a control circuit 102 and a transformer 103. The output of this transformer 103 is connected to a rectification circuit 104 and the rectified output is impressed to a detection circuit 101 and at the same time connected to a voltage level shift circuit 106 through a filter circuit 105. If the output of an operation amplifier 124 of a voltage level shift circuit 106 is connected to the low voltage terminal on the primary side, the voltage on high potential side of a Zener diode 108 in a detection circuit 101 as viewed from a terminal G will indicate the difference between the output voltage of the rectification circuit 104 and that of the operation amplifier 124. Consequently, the Zener diode 108 can be selected regardless of the voltage, so that an operating point good at temperature characteristic can be selected.
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