JPS60163119A - Reset device - Google Patents

Abstract

PURPOSE:To prevent malfunction by providing a delay circuit provided with a charging circuit and a rapid discharge circuit so as to operate an output circuit after a prescribed time at release of reset of a control circuit and stop the output circuit at reset. CONSTITUTION:In throwing a switch 2, a power supply voltage VDD of a CPU1 rises with an impedance of the circuit and a capacitor 3 and reaches a potential of a Zener diode 25. When the power supply voltage VDD reaches a minimum guarantee voltage V1 of the CPU1, a base voltage VB is higher than a voltage VE, a voltage comparison means 5a is conductive, a switching circuit 9 is turned on, the reset terminal voltage of the CPU1 reaches a high level, the operation of the CPU1 is started and also the charging of a capacitor 37 of a delay circuit 36 is started, a transistor (TR) 17 is turned on after a prescribed time and a light emitting diode is lighted by the high level output from an output terminal 1b of the CPU1. When the reset terminal voltage goes to a low level, a TR39 is turned on and rapid charging is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device suitable for use in control circuits such as microcomputer circuits, integrated circuits and the like.

Conventional Structure and Problems Conventionally, cent devices have been used for control circuits such as microcomputer circuits and integrated circuits. The conventional reset device as described above will be described below with reference to the drawings. FIG. 1 shows an electrical circuit diagram of the conventional reset device. In Figure 1, 1 is a microcomputer, 2 is a switch, 3 is a capacitor, and 4
il'lj: DC power supply; 5 is an N P N l-transistor; voltage comparison means 5ai for comparing the reference voltage of the constant voltage diode 6 and the input voltage formed by the voltage divided by the resistors 7 and 8; Configure. 9 is a switching circuit operated by the output signal of this voltage comparison means 5a, and this switching circuit 9 has resistors 10, 11°, 12.13,
14 and a PNP) transistor 13. A resistor 11 and a resistor 14 are connected in series to the collector of the PNP transistor 13 of the switching circuit 9, and the base of an NPN transistor 17 is connected via the n1 resistor 11.

A display circuit operated by the output signal of the 18H microcomputer 1, this display circuit 18 is
9 and NPN) transistor 2o and resistors 21 and 22. The emitter of the NPN transistor 20 of the display circuit 18 is connected to the collector of the NPN transistor 1γ, and the light emitting diode 19 of the display circuit 18 does not emit light unless the NPN transistor 17 is conductive. . Note that 23.24 is the resistance, 25
i'j: a constant voltage diode for producing the power supply voltage DD of the microcomputer 1; 26 is a diode; 27 is a capacitor; FIG. 2 shows the voltage waveform of the capacitor in FIG.
The base voltage of a, ■ E is the voltage of the constant voltage diode 6, ■
DD is the power supply voltage of the microcomputer 1, and RD is the reset terminal voltage of the microcomputer 1. In the above configuration, the operation will be explained with reference to FIG.
increases slowly due to the impedance of the capacitor 3 and the circuit, and stabilizes at the potential of the constant voltage diode 25. At this time, when ■DD becomes equal to or higher than the minimum guaranteed voltage 71 of the microconbeater 1 at time t2,
VB becomes higher than ■E, and the voltage comparison means 6a becomes conductive. When the voltage comparison means 5a becomes conductive, a current flows through the base of the PNP transistor 13 of the switching circuit 9, and the PNP transistor 13 also becomes conductive. Therefore, the reset terminal voltage ■RD of the microcombico-1 is HI.
When the GH level is set, the microcomputer 1 starts operating. At this time, a current flows through the resistor 11 to the source of the NPN transistor 17, and the NPN transistor 17 becomes conductive. At this time, if a HIGH level signal is output from the output terminal 1b of the microcomputer, the NPN
The transistor 20 becomes conductive, current flows through the light emitting diode 19, and the light emitting diode 19 emits light.

Next, at time t3, when switch 2 is opened, the base voltage of voltage comparison means 5a becomes the voltage of capacitor 27 divided by resistor 7 and resistor 8, and the supplied voltage is It has been slowly descending ever since. Then, at time t4, the microcomputer 1
When the power supply voltage vDD becomes lower than the minimum guaranteed voltage v1, the base voltage VB of the voltage comparison means 5a becomes the emitter voltage ■
E becomes smaller than E, the voltage comparison means 5a becomes non-conductive, and the base current of the PNP) transistor 13 of the switching circuit 9 does not flow, and the PNP) transistor 1
3 is non-conductive. Therefore, υ of microcomputer 1
The voltage at the terminal terminal ■RD becomes LOW level, the operation of the microcomputer 1 stops, and the base current of the NPN transistor 17 also stops flowing, and the NPN transistor 17 becomes non-conductive, and the light emitting diode 19 becomes NP.
Even if the N transistor 20 is conductive, no light is emitted.

However, in the above configuration, when the reset of the microcomputer 1 is released at time t2 and the microcomputer 1 starts operating, a HIGH level signal is output to the output terminal 1b etc. for a short time due to a problem with the internal configuration of the microcomputer 1. In this case, the display circuit 18 may malfunction. For that purpose, microcomputer 1 started operating several hundred meters from several meters east.
It was necessary to stop the operation of the output circuit during the period c, and to stop the output circuit instantly when the operation of the microcomputer 1 stopped.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention has been developed to solve the problem of controlling the speed of control circuits ranging from several meters to hundreds of meters after a control circuit such as a microcomputer starts operating.
The purpose of the present invention is to provide a reset device that can stop the operation of the output circuit during the period, and can stop the output circuit at the same time as the control circuit stops the operation.

Structure of the Invention To achieve this object, the reset device of the present invention includes a voltage comparing means for comparing a reference voltage and an input voltage, and a first reset device operated by an output signal of the voltage comparing means. a second switching circuit; a control circuit that operates based on the output signal of the first switching circuit; and a delay that operates based on the output signal of the second switching circuit and controls the operation of the output circuit of the control circuit. This delay circuit is composed of a charging circuit using a resistor and a capacitor, a rapid discharging circuit using a transistor, and a switching circuit. With this configuration, the output circuit of the control circuit is stopped when a certain period of time has elapsed since the control circuit started operating, and after the output circuit of the control circuit has started operating, the output circuit is stopped at the same time as the control circuit is stopped. The circuit will also stop.

Description of Leprosy Example Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows an electrical circuit diagram of a reset device in one embodiment of the present invention. In FIG. 3, the same symbols as those in FIG.
1 is a second switching circuit, and this second switching circuit 31 is composed of resistors 32, 33, 34 and a PNP transistor 35. 36 is a delay circuit, and this delay circuit 36 includes a charging circuit consisting of a capacitor 37 and a resistor 38, a rapid discharging circuit consisting of a PNP) transistor 39, and a PNP transistor 39.
It is constituted by a switching circuit including an NP transistor 4o and resistors 41 and 42. 43 is a resistance. FIG. 4 shows the voltage waveform of the capacitor in FIG. 3, where cc is the voltage of the DC power supply 4, VB is the base voltage of the voltage comparison means 5a, and
E is the voltage of the constant voltage diode 6, ■DD is the power supply voltage of the microcomputer 1, ■RD is the terminal voltage of the reset terminal of the microcomputer 1, and ■Ds is the base voltage of the NPN transistor 17.

In the above configuration, the operation will be explained with reference to FIG. 4. If the switch 2 is closed and the DC power supply 4 is turned on at time t1, the power supply voltage of the microcomputer 1 D
D rises slowly due to the impedance of the capacitor 3 and the circuit, and stabilizes at the potential of the constant voltage diode 25. At this time, when the power supply voltage ■DD becomes equal to or higher than the minimum guaranteed voltage 71 of the microcomputer 1 at time t2, the base voltage VB becomes higher than the voltage ■E,
The voltage comparison means 5a becomes conductive. When the voltage comparison means 5a becomes conductive, a current flows to the base of the PNP transistor 13 of the first switching circuit 9, and the PNP transistor 13
It also conducts. Therefore, the reset terminal voltage RD of the microcomputer 1 becomes HIGH level, and the microcomputer 1 starts operating. Further, at the same time as the first switching circuit 9 operates, current also flows to the base of the PNP transistor 35 of the second switching circuit 31, and the PN
P transistor 35 also becomes conductive. PNP) transistor 3
6 becomes conductive, the PNP of the delay circuit 36)
9 becomes non-conductive, and charging of the capacitor 3 starts due to the time constant with the resistor 38. By charging the capacitor 37, the PNP) transistor 4 at time t3
When the voltage between the base and emitter of 0 becomes approximately 0.7V or more, the PNP) transistor 40 becomes conductive and current flows to the base of the NPN) transistor 17 through the resistor 41.
Transistor 17 becomes conductive. Therefore, when a pH-level signal is output from the output terminal 1b of the microcomputer 1, the NPN transistor 20 becomes conductive, current flows through the light emitting diode 19, and the light emitting diode 19 emits light.

Next, at time t4, when the switch 2 is opened, the voltage across the capacitor 27 divided by the resistor 7.8 is applied to the base voltage of the voltage comparison means 6a; It has been slowly descending since then.

Then, at time t5, when the power supply voltage DD becomes equal to or lower than the minimum guaranteed voltage 1, the base voltage VB of the voltage comparator 5a becomes smaller than the emitter voltage E, and the voltage comparator 5a becomes non-conductive and the first switching PN of circuit 9
P) transistor 13 and second switching circuit 31
(PNP) The base current of transistor 35 no longer flows, and PNP transistor 13.35 becomes non-conductive. Therefore, the reset terminal voltage vRD of the microcomputer 1
goes to LOW level, the operation of the microcomputer stops, and at the same time, current flows to the base of the delay circuit 36 via the resistor 34, and the PNP
) The transistor 39 becomes conductive. Therefore, the charging voltage of the capacitor 37 is instantaneously discharged by the rapid discharge circuit formed by the PNP transistor 39, and the base and emitter of the PNP run raster 400 are short-circuited, and the PNP transistor 4Q becomes non-conductive. Therefore, the base current of the NPN transistor 17 stops flowing, and the NPNI transistor 17 becomes non-conductive.

As described above, according to this embodiment, by providing the delay circuit 36, after the reset of the microcomputer 1 is released, the display circuit 18 operates for a certain period of time determined by the time constant of the capacitor 3 and the resistor 38. By stopping the /)-board and software of the microcomputer 1, the output terminal 1b may go high when the power is turned on.
Even if the light emitting diode 19 reaches the IGH level, the light emitting diode 19 will not erroneously emit light. Further, since the voltage of the capacitor 37 is rapidly discharged by the PNP transistor 39 when the power is turned off, malfunction can be reliably prevented even when the power is turned on subsequently.

Effects of the Invention As is clear from the above practical example, according to the present invention, a delay circuit including a charging circuit and a rapid discharging circuit using a resistor and a capacitor is provided, and the output circuit is operated after a certain period of time when the control circuit is released from reset. In this case, when the control circuit is reset, the output circuit is stopped at the same time, thereby preventing the output circuit of the control circuit from malfunctioning.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional reset device, FIG. 2 is a diagram showing voltage waveforms at various parts thereof, FIG. 3 is an electrical circuit diagram of a reset device in an embodiment of the present invention, and FIG. It is a figure which shows the voltage waveform of each part of a figure. 1...Microcomputer, 5a...
Voltage comparison means, 9...first switching circuit, 18...display circuit, 31...second switching circuit, 36...delay circuit. Figure 1 /a, /child 21g Electric power tt2 t3 Lu →Saitama section book rotation

Claims (2)

[Claims] (1) A voltage comparison means for comparing a reference voltage and an input voltage, a first switching circuit and a second switching circuit that operate according to the output signal of the voltage comparison means, and a voltage comparison means that operates according to the output signal of the first switching circuit. A reset device 0 comprising a control circuit that operates and a delay circuit that operates based on an output signal of the second switching circuit, and that operates an output circuit of the control circuit based on the output of the delay circuit. (2) The reset according to claim 1, wherein the delay circuit is constituted by a charging circuit using a resistor and a capacitor, a rapid discharging circuit using a transistor, and a third switching circuit that operates according to the output signal of the charging circuit. Device.