| 摘要 |
PURPOSE:To improve the efficiency and stability and to attain small sized power supply, by making use of merits of a switching power supply and a series dropper power supply and compensating demerits of them through combination. CONSTITUTION:An error detection circuit 25 detects a voltage difference between a reference voltage terminal 28 and an error detecting terminal 9 connected to an output 17. A voltage of a base 18 of a transistor (TR)3 is changed in response to this error voltage and the base bias voltage of the TR3 is controlled so that the error voltage is about zero. In a switching power supply 1, the switching operation of a switching circuit 19 is controlled via a modulation circuit 20 so that an error voltage detected at an error detection circuit 23 is about zero, in other words, an output terminal 4 and a reference voltage terminal 7 have almost the same voltage. The output terminal 4 and the base 18 of the Tr are kept to almost the same voltage. |
