A hysteresis comparator circuit

Abstract

The application belongs to the technical field of power electronics, and discloses a hysteresis comparator circuit, which comprises an input end VI, one end of a resistor R1 connected to the input end VI, one end of a resistor R2 and one end of a resistor R4 connected to the other end of the resistor R1, one end of a resistor R3, one end of a capacitor C2 and a pin 1 of a voltage stabilizer U1 connected to the other end of the resistor R2, a pin 3 of the U1 connected to a negative end of an optical coupler OT1, one end of a resistor R5 and one end of a resistor R8, one end of the R7 connected to a positive end of the OT1, the other end of the R7 connected to the other end of the R8 and a port VCC, one end of a resistor R6, one end of a capacitor C1 and the other end of the R5 connected to a pin 3 of a switch tube Q1, 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 connected to a port AGND. The application has the advantages of simple structure, small number of components, high comparison accuracy and flexible application in circuits requiring comparison control.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more particularly to a hysteresis comparator circuit. Background Technology

[0002] With the development of technology, electrical equipment is becoming more intelligent and circuit structures are becoming more complex. Circuits often need to control the switching on and off of the circuit based on the input voltage to protect the safe and reliable operation of downstream circuits and improve equipment reliability. However, some existing circuits are structurally complex, costly, and have poor stability. Some circuits lack voltage hysteresis, causing them to switch on and off continuously when the input voltage reaches a critical point, which can easily damage downstream circuits.

[0003] The TL431 is a controllable precision voltage regulator, whose output voltage can be set to any value from 2.5V to 36V using only two resistors. It is used in many applications to replace Zener diodes, such as in digital voltmeters, operational amplifier circuits, adjustable power supplies, and switching power supplies. The main function of the TL431 is to provide a more stable voltage to the circuit. It is a relatively precise controllable voltage regulator with unique dynamic impedance. In circuits, the TL431 is also used as a parallel voltage regulator.

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

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

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

[0007] A hysteresis comparator circuit includes an input terminal VI, which 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 terminal of an optocoupler OT1, one end of a resistor R5, and one end of a resistor R8. The positive terminal 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 a 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 a TL431, wherein 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, wherein 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 VCC port is connected to a DC power supply.

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

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

[0015] It mainly consists of TL431 chip, resistors, capacitors, optocouplers and switching MOS, and is used in applications that require switching control based on voltage or current magnitude. It can precisely control the conduction and cutoff of optocoupler OT1 according to the input voltage VI, and there is an adjustable range between the conduction voltage and the cutoff voltage, namely the hysteresis voltage, which can be flexibly applied to various circuits that require comparison control. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0017] Figure 1 This is a schematic diagram of a hysteresis comparator circuit according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within 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, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0020] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] Please see Figure 1As shown, this invention provides a hysteresis comparator circuit, including an input terminal VI. The input terminal VI is connected to one end of resistor R1. The other end of resistor R1 is connected to one end of resistor R2 and one end of resistor R4. The other end of resistor R2 is connected to one end of resistor R3, one end of capacitor C2, and pin 1 of a voltage regulator U1. Pin 3 of the voltage regulator U1 is connected to the negative terminal of optocoupler OT1, one end of resistor R5, and one end of resistor R8. The positive terminal of optocoupler OT1 is connected to one end of resistor R7. The other end of resistor R7 is connected to the other end of resistor R8. One end of the resistor R4 is connected to the VCC port. The other end of the resistor R4 is connected to pin 1 of the switching transistor Q1. Pin 3 of the switching transistor 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, 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 the AGND port. This design has the advantages of simple structure, few components, and high comparison accuracy, and can be flexibly applied to various circuits that require comparison control.

[0024] In one implementation, the emitter and collector of the optocoupler OT1 are connected to the circuit to be controlled, which includes a power protection circuit. The voltage regulator U1 is a TL431, with pin 1 as the sampling terminal, pin 2 as the positive terminal, and pin 3 as the negative terminal. The switching transistor Q1 is a MOSFET, with pin 1 as the drain, pin 2 as the source, and pin 3 as 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 noted that any other components used to achieve the above effects should fall within the inventive concept of this invention and should be protected within the scope of this invention. This circuit is designed based on the TL431 chip, providing a comparator circuit with hysteresis function. This circuit has the advantages of simple structure, few components, and high comparison accuracy, and can be flexibly applied to various circuits requiring comparison control.

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

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

[0027]

[0028] When the voltage Vc is greater than the reference voltage of U1 (2.5V), U1 conducts, the voltage at point Va is pulled low to the saturation conduction voltage of U1, Q1 is cut off, and the voltage at point Vc is:

[0029]

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

[0031] State 2: The circuit is operating normally. The input voltage VI decreases from high to low. Because U1 is conducting, the voltage at point Va is pulled low, reaching the saturation conduction voltage of U1. Q1 is in the off state, and the voltage at point Vc is:

[0032]

[0033] When the voltage at point Vc is lower than 2.5V, U1 is cut off, the voltage at point Va rises back to the voltage at point Vcc, Q1 turns on, resistor R4 is reconnected to the voltage divider circuit, the circuit returns to state 1, OT1-B is cut off, and switch OT1-A is opened.

[0034] Because the voltage at point Uc is different in the two states of the circuit, there is a voltage difference. By changing the resistance values ​​of resistors R1, R2, R3, and R4, the voltage hysteresis can be set according to the designer's needs, avoiding the phenomenon of the circuit constantly switching when the critical voltage of input VI is reached, and ensuring the stability and reliability of the circuit.

[0035] Working principle: This invention provides a comparator circuit with hysteresis function, which precisely controls the conduction and cutoff of optocoupler OT1 according to the input voltage VI. The conduction voltage and cutoff voltage have an adjustable range, namely the hysteresis voltage. It is used in scenarios that require switching control based on voltage or current magnitude. It has the advantages of simple structure, few components, and high comparison accuracy, and can be flexibly applied to various circuits that require comparison control.

[0036] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A hysteresis comparator circuit, characterized in that: The circuit includes an input terminal VI, which is connected to one end of resistor R1. The other end of resistor R1 is connected to one end of resistor R2 and one end of resistor R4. The other end of resistor R2 is connected to one end of resistor R3, one end of capacitor C2, and pin 1 of voltage regulator U1. Pin 3 of voltage regulator U1 is connected to the negative terminal of optocoupler OT1, one end of resistor R5, and one end of resistor R8. The positive terminal of optocoupler OT1 is connected to one end of resistor R7. The other end of resistor R7 is connected to the other end of resistor R8 and port VCC. The other end of resistor R4 is connected to pin 1 of switching transistor Q1. Pin 3 of switching transistor Q1 is connected to the other end of resistor R5, one end of capacitor C1, and one end of resistor R6. The other end of capacitor C1, the other end of resistor R6, pin 2 of switching transistor Q1, the other end of resistor R3, the other end of capacitor C2, and pin 2 of voltage regulator U1 are connected to port AGND. The voltage regulator U1 is a TL431, where pin 1 is the sampling terminal, pin 2 is the positive terminal, and pin 3 is the negative terminal; the switching transistor Q1 is a MOSFET, where pin 1 is the drain, pin 2 is the source, and pin 3 is the gate.

2. The hysteresis comparator circuit according to claim 1, characterized in that: 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, characterized in that: The circuit to be controlled includes a power protection circuit.

4. A hysteresis comparator circuit according to claim 1, characterized in that: The VCC port is connected to a DC power supply.

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

Images