Constant voltage circuit

Abstract

Abstract PURPOSE:To stably and surely perform a start up operating an to migrate to a stationary state in a short time of start up, by providing an energizing means which permits a current to flow to an output terminal at the time of applying a power source. CONSTITUTION:Transistors Tr1-Tr4 constitute a differential amplifier circuit, and transistors Tr5 and Tr6 constituted the output means of the differential amplifier circuit, and Tr7-Tr11 constitute a current mirror circuit. A voltage comparator COMP which compares the base-emitter voltage VBE of the transistor Tr6 with a forward directional voltage VF at a time when a forward directional current I5 flows on the series circuit of a diode D1 connected to a circuit power source Vcc and a resistor R4 is attached, and when VBE>VF is detected at the voltage comparator COMP, a voltage is applied on the base of the transistor Tr5. In such a way, a start up characteristic can be improved, and the start up of a system can be performed surely at the time of applying the power source, and also, a rise time can be shortened.

Inventors

• 👤 Kazuhiro Izukawa

Bibliographic Details