Hysteresis comparator circuit

Abstract

The invention belongs to the technical field of power electronics, and discloses a hysteresis comparator circuit which comprises an input end VI, the input end VI is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end of an R2 and one end of an R4, the other end of the R2 is connected with one end of an R3, one end of a capacitor C2 and a pin 1 of a voltage stabilization source U1, a pin 3 of the U1 is connected with the negative end of an optocoupler OT1, one end of an R5 and one end of an R8, the positive end of the OT1 is connected with one end of an R7, and the negative end of the R7 is connected with one end of a resistor R1. The other end of the R7 is connected with the other end of the R8 and a port VCC, the other end of the R4 is connected with a pin 1 of the switching tube Q1, a pin 3 of the Q1 is connected with the other end of the R5, one end of the C1 and one end of the R6, and the other end of the C1, the other end of the R6, a pin 2 of the Q1, the other end of the R3, the other end of the C2 and a pin 2 of the U1 are connected with a port AGND. The circuit has the advantages of being simple in structure, small in element number, high in comparison precision and capable of being flexibly applied to circuits needing comparison control.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a hysteresis comparator circuit. Background Art

[0002] With the development of the times, electrical equipment has become more intelligent and the circuit structure has become more complex. Circuits often need to control the opening and closing of the circuit by the magnitude of the input voltage to protect the safe and reliable operation of the subsequent circuit and improve the reliability of the equipment. In existing circuits, some have complex structures, high costs, and poor stability. Some circuits do not have a voltage hysteresis effect, and the circuit switches continuously at the input critical voltage, which is likely to damage the subsequent circuit.

[0003] TL431 is a precision voltage regulator. The output voltage can be set to any value within the range of 2.5V to 36V with two resistors. In many applications, it is used to replace the zener diode, such as digital voltmeters, operational amplifier circuits, adjustable power supplies, switching power supplies, etc. The main function of TL431 is to make the circuit obtain a more stable voltage. TL431 is a relatively precise controllable voltage regulator with a relatively special dynamic resistance. In the circuit, TL431 is also used as a shunt voltage regulator circuit.

[0004] Therefore, it is necessary to provide a hysteresis comparator circuit, which has the advantages of simple structure, few components, high comparison accuracy, etc., and can be flexibly applied to various circuits that require comparison and control. Summary of the Invention

[0005] The present invention discloses a hysteresis comparator circuit, which can effectively solve the technical problems involved in the background art.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A hysteresis comparator circuit includes an input terminal VI. One end of the input terminal VI is connected to one end of a resistor R1. The other end of the resistor R1 is connected to one end of a resistor R2 and one end of a resistor R4. The other end of the resistor R2 is connected to one end of a resistor R3, one end of a capacitor C2, and pin 1 of a voltage regulator U1. Pin 3 of the voltage regulator U1 is connected to the negative end of an optocoupler OT1, one end of a resistor R5, and one end of a resistor R8. The positive end of the optocoupler OT1 is connected to one end of a resistor R7. The other end of the resistor R7 is connected to the other end of the resistor R8 and port VCC. The other end of the resistor R4 is connected to pin 1 of a switching transistor Q1. Pin 3 of the switching transistor Q1 is connected to the other end of the resistor R5, one end of a capacitor C1, and one end of a resistor R6. The other end of the capacitor C1, the other end of the resistor R6, pin 2 of the switching transistor Q1, the other end of the resistor R3, the other end of the capacitor C2, and pin 2 of the voltage regulator U1 are connected to port AGND.

[0008] As a preferred improvement of the present invention: The emitter and collector of the optocoupler OT1 are connected to the circuit to be controlled.

[0009] As a preferred improvement of the present invention: The circuit to be controlled includes a power protection circuit.

[0010] As a preferred improvement of the present invention: The voltage regulator U1 is TL431, where pin 1 is the sampling terminal, pin 2 is the positive terminal, and pin 3 is the negative terminal.

[0011] As a preferred improvement of the present invention: The switching transistor Q1 is a MOS transistor, where pin 1 is the drain, pin 2 is the source, and pin 3 is the gate.

[0012] As a preferred improvement of the present invention: The port VCC is connected to a DC power supply.

[0013] As a preferred improvement of the present invention: The input terminal VI is connected to a detection voltage terminal.

[0014] The beneficial effects of the present invention are as follows:

[0015] It is mainly composed of a TL431 chip, resistors, capacitors, an optocoupler, and a switching MOS. It is used in application scenarios that require switching control according to the magnitude of voltage or current. It accurately controls the conduction and cutoff of the optocoupler OT1 according to the input voltage VI, and there is an adjustable range between the conduction voltage and the cutoff voltage, that is, the hysteresis voltage, which can be flexibly applied to various circuits that require comparison control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0017] Figure 1 It is a schematic diagram of a hysteresis comparator circuit of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0020] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "fixed", etc. should be understood in a broad sense. For example, "fixed" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0023] Please refer to Figure 1As shown, the present invention provides a hysteresis comparator circuit, including an input terminal VI, wherein the input terminal VI is connected to one end of a resistor R1, the other end of the resistor R1 is connected to one end of a resistor R2 and one end of a resistor R4, the other end of the resistor R2 is connected to one end of a resistor R3, one end of a capacitor C2 and a pin 1 of a voltage stabilizing source U1, the pin 3 of the voltage stabilizing source U1 is connected to the negative end of an optical coupler OT1, one end of a resistor R5 and one end of a resistor R8, the positive end of the optical coupler OT1 is connected to one end of a resistor R7, the other end of the resistor R7 is connected to the other end of the resistor R8 One end of the resistor R4 is connected to the port VCC, the other end of the resistor R4 is connected to the pin 1 of the switch tube Q1, the pin 3 of the switch tube Q1 is connected to the other end of the resistor R5, one end of the capacitor C1 and one end of the resistor R6, the other end of the capacitor C1, the other end of the resistor R6, the pin 2 of the switch tube Q1, the other end of the resistor R3, the other end of the capacitor C2 and the pin 2 of the voltage regulator U1 are connected to the port AGND, which has the advantages of simple structure, small number of components, high comparison accuracy, etc., and can be flexibly applied to various circuits that require comparison control.

[0024] As an implementation mode, the emitter and collector of the optical coupler OT1 are connected to the circuit to be controlled, and the circuit to be controlled includes a power protection circuit. The voltage regulator U1 is TL431, wherein pin 1 is the sampling terminal, pin 2 is the positive terminal, and pin 3 is the negative terminal. The switch tube Q1 is a MOS tube, wherein pin 1 is the drain, pin 2 is the source, and pin 3 is the gate. The port VCC is connected to a DC power supply, and the input terminal VI is connected to the detection voltage terminal. It should be further explained that the use of other components to achieve the above-mentioned effects should all belong to the inventive concept of the present invention and should belong to the protection scope of the present invention. This circuit is designed based on the TL431 chip, and provides a comparator circuit with hysteresis function. This circuit has the advantages of simple structure, small number of components and high comparison accuracy, and can be flexibly applied to various circuits that require comparison control.

[0025] As shown in the figure, VI is the input voltage, VCC is the power supply for this circuit, R1, R2, R3 are input voltage divider resistors, C2 is the filter capacitor for comparison voltage, U1 is the TL431 chip, OT1 is an optocoupler, R7 and R8 are current limiting resistors for the power supply circuit, and R5, R6, R4, C1, and Q1 form a hysteresis control circuit.

[0026] State 1: When the circuit is working, VCC supplies power, and the input voltage VI increases from 0V. Because U1 is not conducting, Va is the VCC voltage, Q1 is in the conducting state, and the voltage at point Vc is:

[0027]

[0028] When the Vc voltage is greater than the reference voltage of U1, which is 2.5V, U1 conducts, and the voltage at point Va is pulled down to the saturation conduction voltage of U1. Q1 is in the cut-off state, and the voltage at point Vc is:

[0029]

[0030] At this time, OT1-B is in the saturation conduction state, and the OT1-A switch conducts.

[0031] State 2: The circuit is working normally. The input voltage VI starts to decrease from high to low. Since U1 conducts, the voltage at point Va is pulled down to the saturation conduction voltage of U1. Q1 is in the cut-off state, and the voltage at point Vc is:

[0032]

[0033] When the voltage at point Vc is lower than 2.5V, U1 cuts off, the voltage at point Va rises back to the Vcc voltage, Q1 conducts, and the resistor R4 is reconnected to the voltage division circuit. The circuit returns to state 1, OT1-B cuts off, and the OT1-A switch disconnects.

[0034] Because the voltage at point Uc is different in the two states of the circuit, there is a voltage difference. As long as the resistance values of the resistors R1, R2, R3, and R4 are changed, the voltage hysteresis can be set according to the designer's requirements, avoiding the phenomenon that the circuit continuously switches at the critical voltage of VI input, and ensuring the stable and reliable operation of the circuit.

[0035] Working principle: Provide a comparator circuit with a hysteresis function, accurately control the conduction and cut-off of the optocoupler OT1 according to the input voltage VI, and there is an adjustable range between the conduction voltage and the cut-off voltage, that is, the hysteresis voltage. It is applied in scenarios where switching control is required according to the magnitude of voltage or current, and has the advantages of simple structure, few components, and high comparison accuracy. It can be flexibly applied to various circuits that require comparison control.

[0036] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples shown here.

Claims

1. A hysteresis comparator circuit, characterized in that: It includes an input terminal VI, the input terminal VI is connected to one end of a resistor R1, the other end of the resistor R1 is connected to one end of a resistor R2 and one end of a resistor R4, the other end of the resistor R2 is connected to one end of a resistor R3, one end of a capacitor C2 and pin 1 of a voltage regulator U1, pin 3 of the voltage regulator U1 is connected to the negative end of an optocoupler OT1, one end of a resistor R5 and one end of a resistor R8, the positive end of the optocoupler OT1 is connected to one end of a resistor R7, the other end of the resistor R7 is connected to the other end of the resistor R8 and port VCC, the other end of the resistor R4 is connected to pin 1 of a switching transistor Q1, pin 3 of the switching transistor Q1 is connected to the other end of the resistor R5, one end of a capacitor C1 and one end of a resistor R6, the other end of the capacitor C1, the other end of the resistor R6, pin 2 of the switching transistor Q1, the other end of the resistor R3, the other end of the capacitor C2 and pin 2 of the voltage regulator U1 are connected to port AGND.

2. The hysteresis comparator circuit according to claim 1, wherein: The emitter and collector of the optocoupler OT1 are connected to the circuit to be controlled.

3. The hysteresis comparator circuit according to claim 2, wherein: The circuit to be controlled includes a power protection circuit.

4. A hysteresis comparator circuit according to claim 1, characterized in that: The voltage regulator U1 is TL431, where pin 1 is the sampling terminal, pin 2 is the positive terminal, and pin 3 is the negative terminal.

5. A hysteresis comparator circuit according to claim 1, characterized in that: The switching transistor Q1 is a MOS transistor, where pin 1 is the drain, pin 2 is the source, and pin 3 is the gate.

6. The hysteresis comparator circuit according to claim 1, wherein: The port VCC is connected to a DC power supply.

7. A hysteresis comparator circuit according to claim 1, characterized in that: The input terminal VI is connected to the detected voltage terminal.

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