| 摘要 |
PURPOSE:To protect a device from an abnormal operation due to a transient state just after the application of a power supply, by constituting a titled circuit so that a transistor (TR) of the driver stage is turned off during a low voltage in the course of power supply voltage increasing just after the application of power supply. CONSTITUTION:The power supply voltage is increased gradually just after the application of power supply. In this case, a voltage higher than the Zener voltage of a Zener diode 2 is not applied to an inverting input terminal (-) of a comparator 7 because of a constant voltage supply comprising a resistor 1 and the Zener diode 2. Further, a power supply voltage divided at resistors 3 and 6 is applied to a noninverting input (+) of the comparator 7. The comparator 7 is inverted when the voltage at the terminal (+) is increased more than the voltage at the terminal (-) and the output goes to a voltage being the high potential of the power supply voltage. Since the output voltage of the comparator 7 is higher than the sum between the Zener voltage of a Zener diode 9 and a base-emitter voltage of a TR11, the TR11 is conductive. A TR14 is conductive through the conduction of the TR11, and the base current of the TR of the driver stage is brought into a state possible for supply. |
