JPS5984167A - Voltage detecting circuit - Google Patents

Abstract

PURPOSE:To obtain a stable voltage detecting circuit which detects abnormality of the voltage of a DC power source regardless of its variation in direction and speed, by interposing a DC/DC converter between the DC power source and a load. CONSTITUTION:The DC/DC converter 4 is constituted by adding a constant voltage function which holds a + or -5% output voltage even when load current fluctuation is added, to >=+ or -10% level input voltage fluctuation. Therefore, a threshold value is set within a range of + or -5-10% abnormal voltages at a point, e.g. + or -6% and a power supply cutoff preannouncement signal Vpf is outputted: the D/D converter 5 holds <=+ or -5% voltage range of the voltage at a point D continuously until the voltage at the point A deviates from + or -6% and attains to + or -10%, so a comparing circuit 3 sends out the secure power supply cutoff preannouncement signal Vpf in an enough margin time.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement in an abnormal voltage detection circuit in a 1n current power supply used in electrical equipment.

(+)1 Technology background In recent years, especially with the development of electronic technology, many electrical devices are using logic circuits based on integrated semiconductor circuits and microprocessors to make their control functions smaller and more reliable. Control means have become widely used. These electronic circuits usually use power sources for their operation, such as l)(,
'5V±10% is the recommended standard, and users usually allow for fluctuations in the power supply voltage and set the power supply to
It is often used by setting the voltage to V±5.

(cl. Prior Art and Problems) Conventionally, the control function of electronic circuits in first-class electrical equipment is usually composed of many combinations and sequential circuits such as registers, flip-flops, or memory and microcontrollers consisting of registers, flip-flops, or sets of these. During the operation of the process, there is an abnormal condition in which the power supply voltage mentioned above randomly deviates from 10V, for example, in the event of a power outage or power failure, the electronic circuit may be destroyed or run out of control, or it may easily malfunction due to noise. A non-volatile memory that continues to retain its lI8 data even when an abnormal operating state occurs or when the power is cut off, such as a bubble memory, may also lose its memory due to the occurrence of an abnormal voltage in its power supply during its convolution/read operation. There are cases where data is destroyed and the characteristics of non-volatile memory are not fully utilized, causing serious damage to the inside and outside of electrical equipment that uses the non-volatile memory.

For this reason, electrical equipment has conventionally been controlled by electronic circuits to detect the occurrence of a normal sacrificial IF that deviates from a preset threshold value from the power supply (no. 5 is received as a power cutoff warning signal). 1,% 0）
For example, a means is provided for preventing damage to the primary equipment outside the gate by causing an emergency stop by the control function in a short period of 10 μs.

m 11'Y]l+l, (bl, tel) Shows a Brookock diagram of a voltage detection circuit for a '1'' power supply that can be carried conventionally. In the figure, 1 is a DC power supply, and 2 is a load 1.3, 3a.
is a comparison circuit, J) is a diode, C is a capacitor, and L is a coil. In order to maintain DCBV ±5% regardless of AC input voltage fluctuations, changes in load current consumption, and changes in the environment such as environmental temperature, it is equipped with a constant voltage function in addition to an AC/DC conversion function.The DC power supply 1 is of a floating type. Batteries such as batteries may also be used.

The load 2 is a power supply load including a control function as described above.

Although the comparison circuit 3 is not shown in the figure, its main component is a differential amplifier circuit consisting of one or more operational amplifiers and a plurality of resistors that set their operating levels. Vref is compared with the input signal voltage vi, and when the input signal voltage i deviates from one or more threshold values preset by the plurality of resistors, the output voltage of the comparator circuit 3 is lowered from the normal potential. The comparator circuit 3a whose input signal voltage Viac is AC is further equipped with an AC/DC conversion function or a phase difference detection function. It is assumed that a power cutoff notice signal Vpf is sent out. Figure 1 Fa) supplies current through diode D, and even if the voltage at point A suddenly drops, the voltage drop at point B is temporarily suppressed by the backflow prevention function of diode D and the charge accumulated in the capacitance of capacitor C. To prevent. This temporary B
Power cutoff notice No. 411 V while the voltage at the point is maintained
Upon receiving the pf, the load 2 takes countermeasures, for example, by urgently stopping its function.

In this circuit, current is constantly supplied through diode D, so in addition to the need to increase the power supply voltage by m due to the forward resistance of diode D and voltage drop Vf, the voltage drop V
As the load current changes due to the current dependence of f, the voltage fluctuation rate with respect to the load increases. Furthermore, since the overvoltage function of the diode D cannot be obtained at the time of overvoltage, there is a drawback that the detection performance is relatively inferior to the detection performance of undervoltage.

Figure 1 [bl is the diode D in Figure 1 + al and the coil L
However, if an abnormal voltage occurs in the DC power supply and the change is gradual, there will be no voltage difference between points A and C, so detection may become impossible.

Figure 1 (cl is a circuit that directly detects A and C, which are the inputs of the DC power supply l. Since the object to be detected is AC, the method of converting it to DC level takes too much detection time and is not practical. The comparator circuit that directly detects the phase of current transformation has a complicated structure, and has the disadvantage that failures in the DC power supply 1 cannot be detected.

(di) Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to detect abnormal operation of a DC power supply as an excess or shortage of voltage without depending on the voltage drop rate of the DC power supply, and to detect deviations from preset threshold values. The purpose of the present invention is to provide a smart voltage detection circuit that is independent of the direction and speed of change, whether excessive or insufficient, and is free from current dependence.

tel Structure of the Invention The purpose of this invention is to provide a current power supply system that supplies a standard voltage to one or more loads, which is configured to supply a standard voltage to the load via a DC-1JC converter, and to supply a standard voltage to the load via a DC-1JC converter. Reference voltage and 1)e-1)(,1
It is characterized by comprising means for comparing and detecting the output voltage of the DC power source input to the converter, and configured to send and notify the power cut-off notice signal to the load when the comparing and detecting means detects an abnormal voltage of the DC power source. This can be achieved by providing a voltage detection circuit that does this.

[f+ Embodiment of the Invention An embodiment of the invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a toleration detection 1iS circuit in one embodiment of the present invention.

In the figure, 1 is a DC power supply, 2 is a load, 3 is a comparison circuit, and 4
is a DC-DC converter and C is a capacitor. Components having the same reference numerals as those in Figure 1 (ai, (bl, (cl)) have the same functions as the conventional common reference numerals. 4 is usually configured with a constant voltage function that maintains an output voltage of ±5- even if load current fluctuations are added to the input voltage fluctuation of ±10-chi level or more. If the voltage abnormality threshold value is set to ±5 to 10%, for example ±6%, and the power cutoff notice signal Vpf is sent, the voltage at point A will deviate from ±6% and reach ±10%. Since the voltage at point D is maintained within ±5% by the converter 4, the comparator circuit 3 can send out the reliable power cutoff warning signal Vpf within a sufficient margin of time. The comparison detection operation by the octopus comparator circuit 3 operates without depending on the fluctuation speed of point A. Also, since the voltage retention at point D can be set arbitrarily without depending on the capacitance value of capacitor C,
DC power supply or DC-
1) A secondary effect of preventing a decrease in response speed in constant voltage stable operation and unstable operation due to ringing that occurs in a C converter can also be obtained. Although the above description is based on a power source supplied to a single load hole, the present invention can be implemented in the same manner with a power source provided through a plurality of load holes or a mutual combination thereof.

tgl DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention is useful because it eliminates the drawbacks of conventional voltage detection circuits and provides a stable voltage detection circuit that is independent of the direction and speed of voltage variation.

[Brief explanation of the drawing]

11'';/1 [al, lbl, (cl is a conventional circuit, pressure detection 1st line 1st path; block diagram; Fig. 2 is a block diagram of a voltage detection circuit in an embodiment of the invention) 0 In the figure, 1 is the DC power supply, 2 is the load, 3.3
A4 is a comparison circuit and 4 is a 1)e-L)C converter. 407- ノU ♂Vref 2nd (d

Claims (1)

[Claims] In a direct current source supply system that supplies a standard voltage to one or more 9 loads, 1) If the standard voltage is supplied to the load via a C-DC converter, a separately preset group Qk is used. It is equipped with a means for comparing and detecting the voltage and the output voltage of the DC power supply input to the #DC-DC converter, and when the comparing and detecting means detects an abnormal voltage of the DC power supply, the power cutoff notice number is issued as mentioned above. A voltage/pressure detection circuit configured to send out a notification to the load.