JPH0223059A - Input/output monitoring circuit for stabilized power supply device - Google Patents

Abstract

PURPOSE:To accurately detect a potential difference between input and output voltages of a voltage stabilization circuit and to protect it by providing a potential difference detection circuit for detecting the potential difference. CONSTITUTION:An input/output potential difference detection circuit 10 for detecting a potential difference of input and output voltages is provided between an input terminal 1a and an output terminal 1c of a voltage stabilization circuit 1. The detection circuit 10 is composed of a series circuit of a Zener diode 11 and a photocoupler 12. Accordingly, when the potential difference of the input and output voltage of the stabilization circuit 1 increases to exceed the breakdown voltage of a Zener diode 11, a light emitting diode 12D is lit. Thus, all malfunctions such as an overvoltage of the input, a low voltage of the output and no voltage of the output can be accurately detected by the sole detection circuit 10 having the photocoupler 12 and the diode 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stabilized power supply device, and particularly to an input/output monitoring circuit that monitors input overvoltage, output no-voltage, and the like.

"Prior Art" Conventionally, a stabilized power supply device has been used to convert a DC voltage that includes pulsating current components into a stable DC voltage.
A switching regulator is an example of such a stabilized power supply device. FIG. 2 shows the configuration of the voltage stabilizing circuit 1 of the switching regulator.

In FIG. 2, an input DC voltage is switched on and off through a switching element 2, smoothed through a smoothing circuit 3, converted into a DC voltage, and output.

This output DC voltage is given to the error voltage amplification circuit 4,
It is compared with a reference voltage, and the difference between the output voltage and the desired value is amplified and taken out, and is applied to the pulse width control drive circuit 5. The pulse width control drive circuit 5 controls the conduction period of the switching element 2 according to the applied error signal, thus stabilizing the output voltage at a predetermined value.

Here, the error voltage amplification circuit 4 has mt!, for example, as shown in FIG. has been done. That is, the operational amplifier 1 divides the output voltage Vo by resistors R1 and R2, and the output terminal and the inverting input terminal are connected via the resistor R3.
The differential voltage between the reference voltage VR applied to the inverting input terminal of the operational amplifier 1 and the divided voltage applied to the non-inverting input terminal of the operational amplifier 41 is output. and How to Use Power Devices” (Seibundo Shinkosha, written by Susumu Hakusho and Jiro Toyo).

Such an error voltage is used to control the conduction period of the switching element 2 as described above. In addition, for example, when this error voltage exceeds a predetermined value, it can be applied to a display device to be driven, thereby making it possible to use it for monitoring the output voltage.

That is, in the conventional stabilized power supply device, when the output voltage drops beyond the allowable range or becomes non-voltage, the error voltage amplification circuit 4 can detect this.

[Problems to be Solved by the Invention] However, the error voltage amplification circuit 4 only monitors abnormalities in the output voltage, and cannot monitor abnormalities in the input voltage.

Therefore, an input/output monitoring circuit shown in FIG. 4 has been proposed which can monitor abnormalities in both the voltage stabilizing circuit voltage and the output voltage. In this circuit, a protective fuse 6 is inserted in series on one supply line to the voltage stabilization circuit 1, and an input voltage detection relay 7 is connected in parallel between the input terminals 1a and 1b of the voltage stabilization circuit 1. to monitor input voltage abnormalities. That is, when the input voltage is within the normal range, the input current is supplied to the voltage stabilizing circuit 1 and the relay 7, and the relay 7 is energized to keep the display device, etc. in one state, and prevent overvoltage. When fuse 6 blows, there is no current to relay 7,
The relay 7 is demagnetized and the display device takes on the other state to detect and notify an abnormality.

Further, an output voltage detection relay 8 is connected in parallel between the output terminals 1c and 1d of the voltage stabilizing circuit 1, and when the output voltage is at a predetermined value, the relay 8 is excited to put the display device etc. in one state and the other When the output voltage becomes low or no voltage due to a short circuit in the voltage stabilizing north circuit il, the relay 8 is demagnetized and the display device etc. are set to the other state to detect and notify an abnormality.

However, since it is necessary to provide relays 7.8 as voltage detection means on each of the input side and output side, the configuration becomes complicated and large. In particular, the relays 7 and 8 have a large configuration among electronic components that have been miniaturized, and a configuration using a plurality of relays increases the size of the device. Also, the relay
The accuracy of the operating voltage is low, and it is difficult to accurately detect how low the output voltage has become to cause the activation, and if you try to increase the detection accuracy to avoid this, you will have to spend a lot of time making adjustments. It takes.

The present invention was made in consideration of the following points, and it monitors input voltage and output voltage with a single circuit without using relays, and detects input overvoltage, output undervoltage, and output no voltage. I/O monitoring of stabilized power supply equipment that can perform
It is intended to provide a Ti''l path.

[Means for solving the problem] In order to solve the problem, the present invention detects the potential difference between the input voltage and the output voltage of the voltage stabilizing circuit, and when the detected potential difference exceeds a predetermined value, An input/output potential difference detection means for generating a signal representing .

[Operation 1] When the input terminal becomes overvoltage and the potential difference between the input voltage and the output voltage exceeds a predetermined value, a signal indicating this is output from the input/output potential difference detection means.

Further, when the output voltage becomes a low voltage or no voltage and the potential difference between the input voltage and the output voltage exceeds a predetermined value, a similar signal is output from the input/output potential difference detection means. That is, detection of input overvoltage and output undervoltage or no output voltage can be performed with a single input/output monitoring circuit.

“Example” An example of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a connection diagram showing the configuration of this embodiment, in which parts corresponding to those in FIG. 21 are given the same reference numerals. In FIG. 1, an input/output potential difference detection circuit 10 is provided between an input terminal 1a and an output terminal 1c of a voltage stabilizing circuit 1 for detecting a potential difference between an input voltage and an output voltage.

In this embodiment, the potential difference detection circuit 10 is composed of a series circuit of a Zener diode 11 and a photocoupler 12. That is, the input terminal 1a of the voltage stabilizing circuit 1
is connected to the anode of the light emitting diode 12D of the photocoupler 12, the cathode of the diode 12D is connected to the cathode of the Zener diode 11, and the anode of the Zener diode 11 is connected to the output terminal IC of the voltage stabilizing circuit 1. Therefore, the potential difference between the input voltage and the output voltage of the voltage stabilizing circuit 1 is
When the breakdown voltage of the light emitting diode 12 exceeds
D is now lit.

In this embodiment, this input/output potential difference detection circuit 10
The detection signal (light beam from the light emitting diode 12D) is used for blowing control of the protective fuse 6 connected in series to the input terminal 1a of the voltage stabilizing circuit 1. Photo coupler 1
A resistor R4 is connected in series to the second phototransistor 12T for light reception, and this series circuit is connected in parallel between the re-input terminals 1a and 1.5 of the voltage stabilizing circuit 1.

When the phototransistor 12T receives the light beam from the light emitting diode 12D, it becomes conductive and causes a current to flow through this series circuit, thereby increasing the current flowing to the protective fuse 6 and promoting the blowing of the protective fuse 6. There is.

In such a configuration, when the input voltage to the voltage stabilizing circuit 4 becomes an overvoltage and increases, and becomes larger than the output voltage from the voltage stabilizing circuit 4 by exceeding the reference potential difference, the Zener diode becomes conductive and the light emitting diode 12D emits light. As a result, the phototransistor 12T becomes conductive, increases the current flowing through the protective fuse, blows the protective fuse, and supplies the overvoltage input voltage to the voltage stabilizing circuit, destroying the inside of the voltage stabilizing circuit. prevent.

In addition, if a short-circuit abnormality or the like occurs inside the voltage stabilizing circuit 4 and the output voltage of the voltage stabilizing circuit drops significantly below a predetermined value or becomes non-voltage, the potential difference between the input voltage and the output voltage will be lower than the predetermined value. The Zener diode becomes conductive and the light emitting diode emits light. Therefore, even when the output voltage is abnormal, the protective fuse 6 blows to stop supplying the input voltage, thereby preventing destruction of electronic components other than the cause of the abnormality in the voltage stabilizing circuit 1.

Therefore, according to the embodiment described above, all abnormalities such as input overvoltage, output low voltage, and no output voltage can be detected with high precision by the single input/output potential difference detection circuit 10 consisting of the photocoupler 12 and the Zener diode 11. can be detected. In addition, since the input voltage monitoring configuration and the output voltage monitoring configuration can be executed by a single circuit 10 without having to provide separate configurations, this combined with not using a relay simplifies the overall configuration. can be taken as a thing.

It should be noted that the input/output potential difference detection circuit 10 is not limited to that of the above-mentioned embodiment. It may be something.

Further, in the above-described embodiment, the detection output of the input/output potential difference detection circuit 10 is used to control the blowing of the protective fuse 6, but it may be used for other purposes. For example, it may be used to notify of an abnormality.

Furthermore, the configuration of the voltage stabilizing circuit 1 is not limited to the switching regulator configuration as shown in FIG. It may have any configuration.

[Effects of the Invention] As described above, according to the present invention, a potential difference detection circuit that detects the potential difference between the input and output voltages of the voltage stabilizing circuit is provided, so that even when the input voltage increases, a single circuit can be used. Both abnormalities when the output voltage drops can be accurately detected with a simple configuration, and this detection output can be used to protect the voltage stabilizing circuit, notify abnormalities, etc.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram showing one embodiment of the input/output monitoring circuit of the stabilized power supply according to the present invention, Fig. 2 is a block diagram showing an example of the voltage stabilizing circuit, and Fig. 3 is the error voltage of Fig. 2. A connection diagram showing the basic configuration of an amplifier circuit, and FIG. 4 is a block diagram showing a conventional input/output monitoring circuit. 1... Voltage stabilization circuit, 6... Depth fuse, 1
．． 0...Input/output potential difference detection circuit, 11...Zener diode, 12...For 1 coupler, R4...
··resistance. Patent applicant Oki Electric Industry Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] In a stabilized power supply device equipped with a voltage stabilization circuit that is supplied with a DC input voltage and generates a stabilized output voltage, a potential difference between the input voltage and the output voltage of the voltage stabilization circuit is provided. An input/output power supply device characterized in that an input/output potential difference detection means for detecting the detected potential difference is provided, and when the detected potential difference exceeds a predetermined value, the input/output potential difference detection means generates a signal representing this fact. monitoring circuit.