| 摘要 |
PURPOSE:To keep a far higher stabilized voltage and to simplify the entire circuit by allowing the 2nd constant voltage element to generate a constant voltage different from a constant voltage generated from a constant current source via a switching element. CONSTITUTION:A series circuit comprising a resistor 1 and constant voltage elements 12, 14 is connected inn parallel with a power supply, and a base of a transistor (Tr)3 is connected to a connecting point between the elements 14 and 12. A base of a Tr13 is connected to a connection point between a the resistor 1 and the element 14, a collector of the Tr13 is connected to a terminal A of the power supply and an emitter is used as a output terminal C generating a reference voltage to constitute a startup circuit. Through the constitution above, the Tr3 generates a reference voltage to a terminal B, and a constant voltage being a subtraction of a base-emitter voltage VBE of the TR13 from the sum of Zener voltages of the elements 12, 14 is generated from the terminal C at the same time. The voltage is higher than the reference voltage at the terminal B and used as the other power supply, and in using the voltage as a power supply for constant current source, a stable constant voltage is generated against to a wide power supply input voltage change. |
