Over-voltage and under-voltage protection circuit and lighting lamp

Abstract

The utility model discloses an overvoltage and undervoltage protection circuit and a lighting lamp, comprising a reference voltage module, an undervoltage threshold control module, an undervoltage hysteresis control module, an overvoltage threshold control module, an overvoltage hysteresis control module, a logic control module and a switch control module, the reference voltage module is electrically connected with the under-voltage hysteresis control module and the overvoltage hysteresis control module. The under-voltage threshold control module is electrically connected with an input voltage and the under-voltage hysteresis control module, and the under-voltage hysteresis control module is electrically connected with the logic control module; the overvoltage threshold value control module is electrically connected with the input voltage and the overvoltage hysteresis control module, the overvoltage hysteresis control module is electrically connected with the logic control module, the switch control module is electrically connected with the logic control module and the negative electrode output end, and the input voltage positive electrode is electrically connected with the positive electrode output end. According to the utility model, the phenomenon of frequent output jump caused by fluctuation of input voltage near a threshold value does not exist, and the stability and reliability of a battery power supply system are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of overvoltage and undervoltage protection, and particularly relates to an overvoltage and undervoltage protection circuit and a lighting fixture. Background Art

[0002] Energy storage DC power supply systems are widely used in modern life. These systems typically use batteries as the primary power source to provide power to the load. However, during the charge and discharge process, the voltage of energy storage batteries can experience significant fluctuations, which not only affects the battery life itself but can also damage the power supply system and loads. Therefore, to ensure the stability of battery-powered systems, a detection and protection circuit is used to effectively manage the battery power circuit.

[0003] Currently, common voltage detection and protection circuits typically incorporate a fixed input voltage threshold. This threshold, along with a voltage reference, is fed into a comparator for comparison after passing through a resistor divider network. When the input voltage falls below or rises above the threshold, the comparator outputs a corresponding signal to control the on / off state of the battery-powered circuit, thereby implementing overvoltage and undervoltage protection.

[0004] This design can effectively prevent damage to the power supply system and load caused by abnormal battery voltage to a certain extent. However, when the input voltage fluctuates around the set threshold, the high sensitivity of the comparator can easily trigger frequent output jumps, causing the battery power supply circuit to frequently switch on and off. This frequent switching not only increases circuit power consumption but can also cause unnecessary impact on the power supply system and load, and even cause the protection mechanism to fail. Therefore, a more intelligent and stable overvoltage and undervoltage protection circuit is needed to improve the stability and reliability of battery-powered systems. Utility Model Content

[0005] In view of this, the present invention provides an over-voltage and under-voltage protection circuit and a lighting fixture, the main purpose of which is to solve the problem of frequent on-off of the battery power supply circuit caused by the existing over-voltage and under-voltage protection circuit when the input voltage fluctuates around the set threshold.

[0006] To solve the above problems, the present application provides an over-voltage and under-voltage protection circuit, including a reference voltage module, an under-voltage threshold control module, an under-voltage hysteresis control module, an over-voltage threshold control module, an over-voltage hysteresis control module, a logic control module and a switch control module, wherein:

[0007] The positive input terminal of the reference voltage module is electrically connected to the positive electrode of the power supply, the negative input terminal of the reference voltage module is electrically connected to the negative electrode of the power supply and the negative electrode of the input voltage, and the output terminal of the reference voltage module is electrically connected to the first input terminal of the undervoltage hysteresis control module and the first input terminal of the overvoltage hysteresis control module, respectively; the power input terminal of the undervoltage threshold control module is electrically connected to the positive and negative electrodes of the input voltage, the output terminal of the undervoltage threshold control module is electrically connected to the second input terminal of the undervoltage hysteresis control module, and the output terminal of the undervoltage hysteresis control module is electrically connected to the hysteresis input terminal of the undervoltage threshold control module and the first input terminal of the logic control module, respectively;

[0008] The power input end of the overvoltage threshold control module is electrically connected to the positive and negative poles of the input voltage, the output end of the overvoltage threshold control module is electrically connected to the second input end of the overvoltage hysteresis control module, the first output end of the overvoltage hysteresis control module is electrically connected to the second input end of the logic control module, and the second output end of the overvoltage hysteresis control module is electrically connected to the hysteresis input end of the overvoltage threshold control module; the output end of the logic control module is electrically connected to the input end of the switch control module, and the output end of the switch control module is electrically connected to the negative output end of the protection circuit; the positive pole of the input voltage is electrically connected to the positive output end of the protection circuit.

[0009] In one embodiment of the present invention, optionally, the reference voltage module includes a first resistor, a second resistor, a third resistor and a voltage stabilizing chip, wherein:

[0010] The first end of the third resistor is electrically connected to the positive electrode of the power supply, the second end of the third resistor is electrically connected to the input voltage pin of the voltage stabilizing chip, the ground pin of the voltage stabilizing chip is electrically connected to the negative electrode of the power supply and the negative electrode of the input voltage, the output end of the voltage stabilizing chip is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the first resistor, the first input end of the undervoltage hysteresis control module and the first input end of the overvoltage hysteresis control module respectively, and the second end of the first resistor is electrically connected to the negative electrode of the input voltage.

[0011] In one embodiment of the present invention, optionally, the undervoltage threshold control module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first MOS transistor, wherein:

[0012] A first end of the sixth resistor is electrically connected to the positive electrode of the input voltage, a second end of the sixth resistor is electrically connected to the first end of the fifth resistor and the first end of the seventh resistor, respectively, a second end of the fifth resistor is electrically connected to the first end of the fourth resistor, the source of the first MOS transistor, and the second input end of the undervoltage hysteresis control module, and a second end of the fourth resistor is electrically connected to the negative electrode of the input voltage; a gate of the first MOS transistor is electrically connected to the output end of the undervoltage hysteresis control module, and a drain of the first MOS transistor is electrically connected to the second end of the seventh resistor.

[0013] In one embodiment of the present invention, optionally, the undervoltage hysteresis control module includes an eighth resistor, a ninth resistor and a first comparator, wherein:

[0014] The negative input terminal of the first comparator is electrically connected to the output terminal of the reference voltage module, the positive input terminal of the first comparator is electrically connected to the second end of the fifth resistor, the first end of the fourth resistor, and the source of the first MOS transistor, respectively; the output terminal of the first comparator is electrically connected to the first end of the ninth resistor and the first end of the eighth resistor, respectively; the second end of the eighth resistor is electrically connected to the gate of the first MOS transistor; the output terminal of the first comparator is also electrically connected to the first input terminal of the logic control module through the tenth resistor; the second end of the ninth resistor is electrically connected to the positive electrode of the power supply.

[0015] In one embodiment of the present invention, optionally, the overvoltage threshold control module includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a second MOS transistor, wherein:

[0016] The first end of the thirteenth resistor is electrically connected to the positive electrode of the input voltage, the second end of the thirteenth resistor is electrically connected to the first end of the twelfth resistor and the first end of the fourteenth resistor respectively, the second end of the twelfth resistor is electrically connected to the first end of the eleventh resistor, the source of the second MOS transistor and the second input end of the overvoltage hysteresis control module respectively, and the second end of the eleventh resistor is electrically connected to the negative electrode of the input voltage; the gate of the second MOS transistor is electrically connected to the second output end of the overvoltage hysteresis control module, and the drain of the second MOS transistor is electrically connected to the second end of the fourteenth resistor.

[0017] In one embodiment of the present invention, optionally, the overvoltage hysteresis control module includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a third MOS transistor, and a second comparator, wherein:

[0018] The positive input terminal of the second comparator is electrically connected to the output terminal of the reference voltage module, the negative input terminal of the second comparator is electrically connected to the second end of the twelfth resistor, the first end of the eleventh resistor, and the source of the second MOS transistor respectively, the output terminal of the second comparator is electrically connected to the first end of the seventeenth resistor and the first end of the sixteenth resistor respectively, the second end of the sixteenth resistor is electrically connected to the gate of the third MOS transistor, the drain of the third MOS transistor is electrically connected to the gate of the second MOS transistor and the first end of the fifteenth resistor respectively, and the source of the third MOS transistor is electrically connected to the negative electrode of the input voltage; the output terminal of the second comparator is also electrically connected to the second input terminal of the logic control module through the eighteenth resistor; the second end of the seventeenth resistor and the second end of the fifteenth resistor are both electrically connected to the positive electrode of the power supply.

[0019] In one embodiment of the present invention, optionally, the logic control module includes an AND gate logic unit and an inverter, wherein:

[0020] The first input end of the AND gate logic unit is electrically connected to the output end of the undervoltage hysteresis control module, the second input end of the AND gate logic unit is electrically connected to the output end of the overvoltage hysteresis control module, the power input end of the AND gate logic unit is electrically connected to the positive and negative poles of the power supply, the output end of the AND gate logic unit is electrically connected to the data input end of the inverter, the positive input end of the inverter is electrically connected to the positive pole of the power supply, the negative input end of the inverter is electrically connected to the negative pole of the input voltage, and the output end of the inverter is electrically connected to the input end of the switch control module.

[0021] In one embodiment of the present utility model, optionally, the AND gate logic unit includes a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a fourth MOS transistor and a fifth MOS transistor, wherein:

[0022] The gate of the fourth MOS transistor is electrically connected to the output end of the undervoltage hysteresis control module and the first end of the 20th resistor, respectively; the drain of the fourth MOS transistor is electrically connected to the source of the fifth MOS transistor; the source of the fourth MOS transistor and the second end of the 20th resistor are both electrically connected to the negative electrode of the input voltage; the gate of the fifth MOS transistor is electrically connected to the first output end of the overvoltage hysteresis control module and the first end of the 19th resistor, respectively; the drain of the fifth MOS transistor is electrically connected to the input end of the inverter and the first end of the 21st resistor, respectively; the second end of the 21st resistor is electrically connected to the positive electrode of the power supply; and the second end of the 19th resistor is electrically connected to the negative electrode of the input voltage.

[0023] In one embodiment of the present invention, optionally, the inverter includes a sixth MOS transistor and a seventh MOS transistor, wherein:

[0024] The gate of the sixth MOS transistor is electrically connected to the output end of the AND gate logic unit and the gate of the seventh MOS transistor respectively, the drain of the sixth MOS transistor is electrically connected to the source of the seventh MOS transistor and the input end of the switch control module respectively, the source of the sixth MOS transistor is electrically connected to the negative electrode of the input voltage; and the drain of the seventh MOS transistor is electrically connected to the positive electrode of the power supply.

[0025] In one embodiment of the present invention, optionally, the switch control module includes a twenty-second resistor, a twenty-third resistor, a diode, and an eighth MOS transistor, wherein:

[0026] The first end of the twenty-third resistor is electrically connected to the output end of the logic control module and the cathode of the diode, respectively; the second end of the twenty-third resistor is electrically connected to the anode of the diode, the first end of the twenty-second resistor, and the gate of the eighth MOS transistor, respectively; the drain of the eighth MOS transistor is electrically connected to the negative output end of the protection circuit; the source of the eighth MOS transistor and the second end of the twenty-second resistor are both electrically connected to the negative electrode of the input voltage.

[0027] In addition, the present application also provides a lighting fixture, which includes the above-mentioned over-voltage and under-voltage protection circuit.

[0028] The utility model provides an over-voltage and under-voltage protection circuit and a lighting fixture. The under-voltage hysteresis control module inputs an under-voltage hysteresis signal to the under-voltage threshold control module. When the input voltage is in an under-voltage state, the under-voltage threshold determined by the under-voltage threshold control module increases. Only when the input voltage is less than the increased under-voltage threshold is it determined to be under-voltage, and the state information corresponding to the under-voltage is output, so that the switch control module remains in a continuously disconnected state, and there is no state in which the switch control module frequently jumps. The over-voltage hysteresis control module inputs an over-voltage hysteresis signal to the over-voltage threshold control module. When the input voltage is in an under-voltage state, the under-voltage threshold determined by the under-voltage threshold control module increases. In the overvoltage state, the overvoltage threshold determined by the overvoltage threshold control module is lowered. When the input voltage is higher than the lowered overvoltage threshold, it is determined to be overvoltage, and the status information corresponding to the overvoltage is output, so that the switch control module remains in a continuously disconnected state, and there is no state in which the switch control module frequently jumps. The undervoltage threshold is raised by the undervoltage hysteresis control module, and the overvoltage threshold is lowered by the overvoltage hysteresis control module. There is no phenomenon in which the input voltage fluctuates near the threshold and causes the output to frequently jump, thereby achieving more intelligent and stable over- and undervoltage protection and improving the stability and reliability of the battery-powered system.

[0029] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0031] Figure 1 This is a structural block diagram of an over-voltage and under-voltage protection circuit according to an exemplary embodiment of the present invention;

[0032] Figure 2 The figure is a circuit connection diagram of an over-voltage and under-voltage protection circuit according to an exemplary embodiment of the present invention.

[0033] in,

[0034] Figure 1-Figure 2 The numbers are as follows: 11-reference voltage module; 12-undervoltage threshold control module; 13-undervoltage hysteresis control module; 14-overvoltage threshold control module; 15-overvoltage hysteresis control module; 16-logic control module; 161-AND gate logic unit; 162-inverter; 17-switch control module; R1-first resistor; R2-second resistor; R3-third resistor; D1-voltage regulator chip; R4-fourth resistor; R5-fifth resistor; R6-sixth resistor; R7-seventh resistor; Q1-first MOS tube; R8-eighth resistor; R9-ninth resistor; U2A-first comparator; R10-tenth resistor; R11-eleventh resistor; R12-twelfth resistor; R13-thirteenth resistor; R14-fourteenth resistor; Q2 - second MOS tube; R15 - fifteenth resistor; R16 - sixteenth resistor; R17 - seventeenth resistor; U2B - second comparator; R18 - eighteenth resistor; Q3 - third MOS tube; R19 - nineteenth resistor; R20 - twentieth resistor; R21 - twenty-first resistor; Q4 - fourth MOS tube; Q5 - fifth MOS tube; Q6 - sixth MOS tube; Q7 - seventh MOS tube; R22 - twenty-second resistor; R23 - twenty-third resistor; D2 - diode; Q8 - eighth MOS tube; VCC - positive electrode of power supply; GND - negative electrode of power supply; Vi+ - positive input voltage; Vi-- negative input voltage; Vo+ - positive output terminal of protection circuit; Vo-- negative output terminal of protection circuit. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0036] To further illustrate the technical means and effects employed by the present invention to achieve its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0037] The following combination Figures 1 to 2 The over-voltage and under-voltage protection circuits proposed in some embodiments of the present invention are described.

[0038] In one embodiment, Figure 1 As shown, an over-voltage and under-voltage protection circuit includes a reference voltage module 11, an under-voltage threshold control module 12, an under-voltage hysteresis control module 13, an over-voltage threshold control module 14, an over-voltage hysteresis control module 15, a logic control module 16 and a switch control module 17, wherein:

[0039] The positive input terminal of the reference voltage module 11 is electrically connected to the positive electrode VCC of the power supply, the negative input terminal of the reference voltage module 11 is electrically connected to the negative electrode GND of the power supply and the negative electrode Vi- of the input voltage, respectively, and the output terminal of the reference voltage module 11 is electrically connected to the first input terminal of the undervoltage hysteresis control module 13 and the first input terminal of the overvoltage hysteresis control module 15, respectively; the power input terminal of the undervoltage threshold control module 12 is electrically connected to the positive and negative electrodes of the input voltage, the output terminal of the undervoltage threshold control module 12 is electrically connected to the second input terminal of the undervoltage hysteresis control module 13, and the output terminal of the undervoltage hysteresis control module 12 is electrically connected to the hysteresis input terminal of the undervoltage threshold control module 13 and the first input terminal of the logic control module 16, respectively;

[0040] The power input terminal of the overvoltage threshold control module 14 is electrically connected to the positive and negative poles of the input voltage, the output terminal of the overvoltage threshold control module 14 is electrically connected to the second input terminal of the overvoltage hysteresis control module 15, the first output terminal of the overvoltage hysteresis control module 15 is electrically connected to the second input terminal of the logic control module 16, and the second output terminal of the overvoltage hysteresis control module 15 is electrically connected to the hysteresis input terminal of the overvoltage threshold control module 14; the output terminal of the logic control module 16 is electrically connected to the input terminal of the switch control module 17, and the output terminal of the switch control module 17 is electrically connected to the negative output terminal Vo- of the protection circuit; the positive pole Vi+ of the input voltage is electrically connected to the positive output terminal Vo+ of the protection circuit.

[0041] Specifically, the negative pole of the power supply voltage is connected to the negative pole of the input voltage, so that the reference voltage and the sampling voltage have the same negative pole. The reference voltage module provides a reference voltage for the undervoltage hysteresis control module and the overvoltage hysteresis control module. The undervoltage threshold control module samples the input voltage and inputs the sampled voltage to the undervoltage hysteresis control module. The undervoltage hysteresis control module compares the sampled voltage with the reference voltage and outputs the comparison result. The undervoltage threshold is adjusted according to the comparison result, which is equivalent to raising the undervoltage threshold. When the input voltage is between the raised undervoltage threshold and the initial undervoltage threshold, the undervoltage hysteresis control module considers the input voltage to be undervoltage and outputs a low level to the first input terminal of the logic control module. The overvoltage threshold control module samples the input voltage and inputs the sampled voltage to the overvoltage hysteresis control module. The control module compares the sampled voltage with the reference voltage, outputs a comparison result, and adjusts the overvoltage threshold according to the comparison result, which is equivalent to lowering the overvoltage threshold. When the input voltage is between the initial overvoltage threshold and the lowered overvoltage threshold, the overvoltage hysteresis control module considers the input voltage to be overvoltage and outputs a low level to the second input terminal of the logic control module. The logic control module performs logical judgment based on the output results of the undervoltage hysteresis control module and the output results of the overvoltage hysteresis control module, and outputs the result to the switch control module. The switch control module closes or opens the switch according to the input result of the logic control module, so that the negative electrode of the input voltage is disconnected or closed from the output terminal of the protection circuit.

[0042] The utility model is a protection circuit with dual thresholds. When the abnormal input voltage is between the high threshold and the low threshold, the output of the detection circuit is always kept in a high level or low level state. The circuit designed in this way can avoid frequent jumps in the output level and enhance the anti-interference ability of the voltage detection circuit.

[0043] The supply voltage VCC of the control loop is separated from the input voltage Vi, that is, the supply voltage VCC is not directly taken from the input voltage Vi, but the negative pole of the supply voltage and the negative pole of the input voltage are connected together. The input voltage Vi will not be affected by the low withstand voltage of the control loop, so the input voltage Vi can reach a very high voltage value.

[0044] Compared with the prior art, the over / undervoltage protection circuit of the present application uses an undervoltage hysteresis control module to input an undervoltage hysteresis signal to an undervoltage threshold control module. When the input voltage is in an undervoltage state, the undervoltage threshold determined by the undervoltage threshold control module is increased. Only when the input voltage is less than the increased undervoltage threshold is an undervoltage condition determined, and status information corresponding to the undervoltage condition is output. This ensures that the switch control module remains in a continuously disconnected state, eliminating the switch control module from frequently switching. The overvoltage hysteresis control module uses an overvoltage hysteresis signal to input an overvoltage threshold control module. When the input voltage is in an overvoltage state, the overvoltage threshold determined by the overvoltage threshold control module is lowered. As long as the input voltage is above the lowered overvoltage threshold, an overvoltage condition is determined, and status information corresponding to the overvoltage condition is output. This ensures that the switch control module remains in a continuously disconnected state, eliminating the switch control module from frequently switching. The undervoltage hysteresis control module raises the undervoltage threshold, and the overvoltage hysteresis control module lowers the overvoltage threshold. This eliminates the phenomenon of frequent output switching caused by input voltage fluctuations near the threshold, achieving more intelligent and stable over / undervoltage protection and improving the stability and reliability of the battery-powered system.

[0045] In one embodiment, Figure 2 As shown, the reference voltage module includes a first resistor R1, a second resistor R2, a third resistor R3 and a voltage stabilizing chip, wherein:

[0046] A first end of the third resistor R3 is electrically connected to the positive electrode VCC of the power supply, a second end of the third resistor R3 is electrically connected to the input voltage pin of the voltage regulator chip D1, a ground pin of the voltage regulator chip D1 is electrically connected to the negative electrode GND of the power supply and the negative input voltage electrode Vi-, an output end of the voltage regulator chip D1 is electrically connected to the first end of the second resistor R2, a second end of the second resistor R2 is electrically connected to the first end of the first resistor R1, the first input end of the undervoltage hysteresis control module 13, and the first input end of the overvoltage hysteresis control module 15, respectively, and a second end of the first resistor R1 is electrically connected to the negative input voltage electrode Vi-.

[0047] In this embodiment, the reference voltage uses a voltage regulator chip, the positive power pin of the voltage regulator chip is connected to the positive pole of the power supply, the negative power pin of the voltage regulator chip is connected to the negative pole of the power supply and the negative pole of the input voltage, the voltage regulator chip outputs a voltage of 2.5V, and the reference voltage Vref is set: Vref = R1 / (R1+R2)*2.5V; the 2.5V voltage is divided by the first resistor R1 and the second resistor R2 to obtain more reference voltages Vref, which can make the design parameters of the subsequent threshold protection circuit more convenient.

[0048] In one embodiment, Figure 2 Therefore, the undervoltage threshold control module 12 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and a first MOS transistor Q1, wherein:

[0049] A first end of the sixth resistor R6 is electrically connected to the positive electrode Vi+ of the input voltage. A second end of the sixth resistor R6 is electrically connected to the first end of the fifth resistor R5 and the first end of the seventh resistor R7, respectively. A second end of the fifth resistor R5 is electrically connected to the first end of the fourth resistor R4, the source of the first MOS transistor Q1, and the second input end of the undervoltage hysteresis control module 13, respectively. A second end of the fourth resistor R4 is electrically connected to the negative electrode Vi- of the input voltage. A gate of the first MOS transistor Q1 is electrically connected to the output end of the undervoltage hysteresis control module 13, and a drain of the first MOS transistor Q1 is electrically connected to the second end of the seventh resistor R7.

[0050] The circuit of the utility model uses resistor voltage division to sample undervoltage detection. The undervoltage detection is divided into an upper resistor for undervoltage detection and a lower resistor for undervoltage detection. The equivalent resistor in the circuit composed of the fifth resistor, the sixth resistor, and the seventh resistor is the upper resistor, and the fourth resistor is the lower resistor. The voltage value of the input voltage Vi is sampled through the fourth resistor, the fifth resistor, and the sixth resistor. After resistor voltage division, the voltage value is input to the positive input terminal of the first comparator. The negative input terminal of the first comparator is the reference voltage. The first comparator outputs a comparison result, and the comparison result controls the conduction and shutdown of the first MOS transistor. When the first MOS transistor is turned on, the seventh resistor is effective and connected in parallel with the fifth resistor. The upper resistor of the voltage divider circuit changes, thereby changing the undervoltage threshold. When the first MOS transistor is turned off, the seventh resistor is ineffective and open-circuited, and the resistance of the voltage divider circuit remains unchanged.

[0051] The circuit of the utility model is provided with a controllable switch to protect the state of one of the upper resistors in the circuit being connected in parallel with another resistor, thereby changing the effective value of the upper resistor; the effective value of the upper resistor is changed while the lower resistor remains unchanged, so that the divided voltage of the input voltage under different states can be obtained.

[0052] In one embodiment, Figure 2 As shown, the undervoltage hysteresis control module 13 includes an eighth resistor R8, a ninth resistor R9 and a first comparator U2A, wherein:

[0053] The negative input terminal of the first comparator U2A is electrically connected to the output terminal of the reference voltage module 11, the positive input terminal of the first comparator U2A is electrically connected to the second end of the fifth resistor R5, the first end of the fourth resistor R4, and the source of the first MOS transistor Q1, respectively; the output terminal of the first comparator U2A is electrically connected to the first end of the ninth resistor R9 and the first end of the eighth resistor R8, respectively; the second end of the eighth resistor R8 is electrically connected to the gate of the first MOS transistor Q1; the output terminal of the first comparator U2A is also electrically connected to the first input terminal of the logic control module 16 via the tenth resistor R10; the second end of the ninth resistor R9 is electrically connected to the positive electrode VCC of the power supply.

[0054] Specifically, (1) when the input voltage is within the normal range, the positive input terminal voltage Vp of the first comparator is greater than the negative input terminal voltage Vn. After comparison, the first comparator outputs a high level, the first MOS transistor Q1 is turned on, and the fifth resistor R5 and the seventh resistor R7 are connected in parallel. At this time, the undervoltage low threshold value Vi(L1) can be set. According to circuit analysis, it can be obtained that: Vi(L1) = (R4 + R5 / / R7 + R6) / R4 * Vref.

[0055] (2) When the input voltage Vi is undervoltage, the positive input voltage Vp of the first comparator is less than the negative input voltage Vn. The first comparator outputs a low level after comparison, the first MOS transistor Q1 is turned off, the fifth resistor R5 is enabled, and the seventh resistor R7 is open. At this point, the undervoltage high threshold Vi(H1) can be set. According to circuit analysis, we can obtain: Vi(H1) = (R4 + R5 + R6) / R4 * Vref.

[0056] According to the circuit analysis, it can be obtained that: undervoltage input hysteresis voltage = undervoltage high threshold - undervoltage low threshold,

[0057] That is, ΔVi1=Vi(H1)-Vi(L1)=(R5-R5 / / R7) / R4*Vref.

[0058] The present invention can achieve dual-threshold control. When the voltage input is within the normal voltage range, the undervoltage threshold is the initial undervoltage low threshold: Vi(L1) = (R4+R5 / / R7+R6) / R4*Vref. When the undervoltage input is undervoltage, the undervoltage threshold is adjusted to the raised undervoltage high threshold: Vi(H1) = (R4+R5+R6) / R4*Vref. Since the undervoltage high threshold is higher than the undervoltage low threshold, when the input voltage is between the undervoltage high threshold and the undervoltage low threshold, the input voltage is considered to be undervoltage, and the undervoltage hysteresis control module outputs a low level and maintains the low level state to avoid frequent tripping when fluctuating near the normal threshold. In this way, the circuit can achieve the function of undervoltage buffering. When the input voltage is higher than the undervoltage high threshold, the input voltage is considered to be normal, and the undervoltage hysteresis control module outputs a high level.

[0059] In one embodiment, Figure 2 As shown, the overvoltage threshold control module 14 includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a second MOS transistor Q2, wherein:

[0060] A first end of the thirteenth resistor R13 is electrically connected to the positive electrode Vi+ of the input voltage. A second end of the thirteenth resistor R13 is electrically connected to the first end of the twelfth resistor R12 and the first end of the fourteenth resistor R14, respectively. A second end of the twelfth resistor R12 is electrically connected to the first end of the eleventh resistor R11, the source of the second MOS transistor Q2, and the second input end of the overvoltage hysteresis control module 15, respectively. A second end of the eleventh resistor R11 is electrically connected to the negative electrode Vi- of the input voltage. A gate of the second MOS transistor Q2 is electrically connected to the second output end of the overvoltage hysteresis control module 15, and a drain of the second MOS transistor Q2 is electrically connected to the second end of the fourteenth resistor R14.

[0061] In this embodiment, the circuit of the present invention uses resistor voltage division to sample overvoltage detection. The overvoltage detection is divided into an upper resistor for overvoltage detection and a lower resistor for overvoltage detection. The equivalent resistor in the circuit composed of the twelfth, thirteenth, and fourteenth resistors is the upper resistor, and the eleventh resistor is the lower resistor. The voltage value of the input voltage Vi is sampled through the eleventh, twelfth, and thirteenth resistors, and after resistor voltage division, is input to the negative input terminal of the second comparator. The positive input terminal of the second comparator serves as the reference voltage. The second comparator outputs a comparison result, which controls the conduction and shutdown of the second MOS transistor. When the second MOS transistor is on, the fourteenth resistor is effective and connected in parallel with the twelfth resistor, and the upper resistor of the voltage divider circuit changes, thereby changing the overvoltage threshold. When the second MOS transistor is off, the fourteenth resistor is ineffective and open-circuited, and the resistance of the voltage divider circuit remains unchanged.

[0062] The circuit of the utility model is provided with a controllable switch to protect the state of one of the upper resistors in the circuit being connected in parallel with another resistor, thereby changing the effective value of the upper resistor; the effective value of the upper resistor is changed while the lower resistor remains unchanged, so that the divided voltage of the input voltage under different states can be obtained.

[0063] The circuit of the utility model adopts a 2-way output comparator to compare the divided voltage of the input voltage in different states with the reference voltage Vref, and then outputs high and low levels to control the controllable switch, which in turn controls the effective value of the upper resistor, thus forming a closed-loop control.

[0064] In one embodiment, Figure 2 As shown, the overvoltage hysteresis control module 15 includes a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, a third MOS transistor Q3 and a second comparator U2B, wherein:

[0065] The positive input terminal of the second comparator U2B is electrically connected to the output terminal of the reference voltage module 11. The negative input terminal of the second comparator U2B is electrically connected to the second terminal of the twelfth resistor R12, the first terminal of the eleventh resistor R11, and the source of the second MOS transistor Q2. The output terminal of the second comparator U2B is electrically connected to the first terminal of the seventeenth resistor R17 and the first terminal of the sixteenth resistor R16. The second terminal of the sixteenth resistor R16 is electrically connected to the gate of the third MOS transistor Q3. The drain of the third MOS transistor Q3 is electrically connected to the gate of the second MOS transistor Q2 and the first terminal of the fifteenth resistor R15. The source of the third MOS transistor Q3 is electrically connected to the negative input voltage Vi-. The output terminal of the second comparator U2B is also electrically connected to the second input terminal of the logic control module 16 via the eighteenth resistor R18. The second terminal of the seventeenth resistor R17 and the second terminal of the fifteenth resistor R15 are both electrically connected to the positive terminal VCC of the power supply.

[0066] Specifically, (1) when the input voltage Vi is within the normal range, the negative input terminal voltage Vq in the second comparator is less than the positive input terminal voltage Vm. The second comparator outputs a high level after comparison, the third MOS transistor Q3 is turned on, the second MOS transistor Q2 is turned off, the fourteenth resistor R14 is open, and the twelfth resistor R12 is effective. At this time, the overvoltage high threshold Vi(H2) can be set. According to circuit analysis, it can be obtained that: Vi(H2) = (R11 + R12 + R13) / R11 * Vref.

[0067] (2) When the input voltage Vi is overvoltage, the voltage Vq at the negative input terminal of the second comparator is greater than the voltage Vm at the positive input terminal. The second comparator outputs a low level after comparison, turning on the second MOS transistor Q2 and turning off the third MOS transistor Q3. The twelfth resistor R12 and the fourteenth resistor R14 are connected in parallel, and the upper resistance changes. At this time, the overvoltage low threshold Vi(L2) can be set. According to circuit analysis, it can be obtained that: Vi(L2) = (R11 + R12 / / R14 + R13) / R11 * Vref.

[0068] According to the circuit analysis, it can be obtained that: overvoltage input hysteresis voltage = overvoltage high threshold - overvoltage low threshold,

[0069] That is, ΔVi2=Vi(H2)-Vi(L2)=(R12-R12 / / R14) / R11*Vref.

[0070] The present invention can achieve dual-threshold control. When the voltage input is within the normal voltage range, the overvoltage threshold is the initial overvoltage high threshold: Vi(H2) = (R11 + R12 + R13) / R11 * Vref. When the overvoltage input is overvoltage, the overvoltage threshold is the lowered overvoltage low threshold: Vi(L2) = (R11 + R12 / / R14 + R13) / R11 * Vref. Since the overvoltage high threshold is higher than the overvoltage low threshold, when the input voltage is between the overvoltage high threshold and the overvoltage low threshold, the input voltage is considered to be overvoltage, and the overvoltage hysteresis control module outputs a low level and maintains the low level state, avoiding frequent jumps when fluctuating near the normal threshold. In this way, the circuit can achieve the function of overvoltage buffering. When the input voltage is lower than the overvoltage low threshold, the input voltage is considered to be normal, and the overvoltage hysteresis control module outputs a high level.

[0071] In one embodiment, the logic control module 16 includes an AND gate logic unit 161 and an inverter 162, wherein:

[0072] A first input terminal of the AND gate logic unit 161 is electrically connected to the output terminal of the undervoltage hysteresis control module 13, a second input terminal of the AND gate logic unit 161 is electrically connected to the output terminal of the overvoltage hysteresis control module 15, a power input terminal of the AND gate logic unit 161 is electrically connected to the positive and negative poles of the power supply, an output terminal of the AND gate logic unit 161 is electrically connected to the data input terminal of the inverter 162, a positive input terminal of the inverter 162 is electrically connected to the positive pole VCC of the power supply, a negative input terminal of the inverter 162 is electrically connected to the negative input voltage Vi-, and an output terminal of the inverter 162 is electrically connected to the input terminal of the switch control module 17.

[0073] Specifically, the AND gate logic unit performs a logical judgment on the voltage levels output by the undervoltage hysteresis control module and the overvoltage hysteresis control module. The AND gate logic unit outputs inverted logic. The signal output by the AND gate logic unit is then inverted by an inverter and output to the switch control module. The circuit's operating logic is as follows:

[0074] When undervoltage input occurs, the undervoltage hysteresis control module outputs a low level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, it outputs a high level, and after processing by the inverter, it outputs a low level;

[0075] When overvoltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a low level; after judgment by the AND gate logic unit, it outputs a high level, and after processing by the inverter, it outputs a low level;

[0076] When normal voltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, it outputs a low level, and after processing by the inverter, it outputs a high level.

[0077] In one embodiment, Figure 2 As shown, the AND gate logic unit 161 includes a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a fourth MOS transistor Q4 and a fifth MOS transistor Q5, wherein:

[0078] The gate of the fourth MOS transistor Q4 is electrically connected to the output end of the undervoltage hysteresis control module 13 and the first end of the 20th resistor R20, respectively. The drain of the fourth MOS transistor Q4 is electrically connected to the source of the fifth MOS transistor Q5. The source of the fourth MOS transistor Q4 and the second end of the 20th resistor R20 are both electrically connected to the negative input voltage electrode Vi-. The gate of the fifth MOS transistor Q5 is electrically connected to the first output end of the overvoltage hysteresis control module 15 and the first end of the nineteenth resistor R19, respectively. The drain of the fifth MOS transistor Q5 is electrically connected to the input end of the inverter 162 and the first end of the twenty-first resistor R21, respectively. The second end of the twenty-first resistor R21 is electrically connected to the positive electrode VCC of the power supply. The second end of the nineteenth resistor R19 is electrically connected to the negative input voltage electrode Vi-.

[0079] Specifically, the AND gate logic unit makes a logical judgment on the output level of the undervoltage hysteresis control module and the output level of the overvoltage hysteresis control module. The AND gate logic unit outputs inverted logic, that is: (1) the level of both input signals is "1", the level of the output signal is "0"; (2) the level of one input signal is "0", the level of the output signal is "1". The working logic of the circuit is as follows:

[0080] When undervoltage input occurs, the undervoltage hysteresis control module outputs a low level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, the output is a high level;

[0081] When overvoltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a low level; after judgment by the AND gate logic unit, the output is a high level;

[0082] When normal voltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, it outputs a low level.

[0083] In one embodiment, Figure 2 As shown, the inverter 162 includes a sixth MOS transistor Q6 and a seventh MOS transistor Q7, wherein:

[0084] The gate of the sixth MOS transistor Q6 is electrically connected to the output end of the AND gate logic unit 161 and the gate of the seventh MOS transistor Q7, respectively. The drain of the sixth MOS transistor Q6 is electrically connected to the source of the seventh MOS transistor Q7 and the input end of the switch control module 17, respectively. The source of the sixth MOS transistor Q6 is electrically connected to the negative electrode of the input voltage Vi-; the drain of the seventh MOS transistor Q7 is electrically connected to the positive electrode VCC of the power supply.

[0085] Specifically, such as Figure 2 As shown, the inverter circuit is composed of an upper P-MOS tube and a lower N-MOS tube. The level of the output signal of this circuit is inversely proportional to the level of the input signal. The relationship is as follows: the high-level signal output by the AND gate logic unit is processed by the inverter and outputs a low-level signal; the low-level signal output by the AND gate logic unit is processed by the inverter and outputs a high-level signal.

[0086] In one embodiment, Figure 2 As shown, the switch control module includes a twenty-second resistor R22, a twenty-third resistor R23, a diode D2 and an eighth MOS transistor Q8, wherein:

[0087] A first end of the twenty-third resistor R23 is electrically connected to the output end of the logic control module 16 and the cathode of the diode D2, respectively. A second end of the twenty-third resistor R23 is electrically connected to the anode of the diode D2, the first end of the twenty-second resistor R22, and the gate of the eighth MOS transistor Q8, respectively. A drain of the eighth MOS transistor Q8 is electrically connected to the negative output end of the protection circuit. A source of the eighth MOS transistor Q8 and a second end of the twenty-second resistor R22 are both electrically connected to the negative input voltage electrode Vi-.

[0088] Specifically, battery-powered systems typically operate at low voltage and high current. To control a MOS transistor that carries high current, it's crucial to quickly turn the MOS transistor on and off to reduce switching losses and heat generation. To achieve this, a protection circuit is required to quickly charge and discharge the MOS transistor's gate. The eighth MOS transistor of the present invention is an N-MOS transistor, whose on and off are controlled by high and low-level signals output by an inverter.

[0089] The working state is as follows: the signal output from the inverter is high level, which controls the conduction of the N-MOS tube, so that the negative output terminal of the protection circuit is connected to the negative terminal of the input voltage, that is, the DC power supply system is powered;

[0090] The signal output by the inverter is low level, which controls the closure of the N-MOS tube, disconnecting the negative output terminal of the protection circuit from the negative pole of the input voltage, that is, the DC power supply system is powered off.

[0091] This invention uses a novel method to realize fast charging and discharging of the gate of the eighth MOS tube in the switch control module, realizes fast conduction and shutdown of the MOS tube, reduces system loss, and improves conversion efficiency. In addition, the circuit structure is simple, convenient to design, and easy to debug. By using conventional devices to design the circuit, input overvoltage and undervoltage protection control can be achieved, which has great advantages in cost and application.

[0092] In summary, the working logic of the under-voltage and over-voltage protection circuit is as follows:

[0093] (1) When undervoltage is input, the undervoltage hysteresis control module outputs a low level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, it outputs a high level; after processing by the inverter, it outputs a low level signal; it controls the N-MOS tube in the switch control module to be closed, which will disconnect the negative output terminal of the protection circuit from the negative pole of the input voltage, that is, the DC power supply system is powered off.

[0094] (2) When overvoltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a low level; after judgment by the AND gate logic unit, it outputs a high level; after processing by the inverter, it outputs a low level signal; it controls the closure of the N-MOS tube in the switch control module, which will disconnect the negative output terminal of the protection circuit from the negative pole of the input voltage, that is, the DC power supply system is powered off.

[0095] (3) When normal voltage is input, the undervoltage hysteresis control module outputs a high level, and the overvoltage hysteresis control module outputs a high level; after judgment by the AND gate logic unit, it outputs a low level; after processing by the inverter, it outputs a high level signal; it controls the conduction of the N-MOS tube in the switch control module, which will connect the negative output terminal of the protection circuit to the negative pole of the input voltage, that is, the DC power supply system is powered.

[0096] In addition, the present application also provides a lighting fixture, which includes the over-voltage and under-voltage protection circuit described above.

[0097] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

[0098] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0099] These and other characteristics of the present application will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0100] It should also be understood that although the present application has been described with reference to certain specific examples, those skilled in the art will readily be able to implement many other equivalent forms of the present application.

[0101] The above and other aspects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0102] Specific embodiments of the present application will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments described are merely examples of the present application and may be implemented in a variety of ways. Familiar and / or repetitive functions and structures are not described in detail to avoid obscuring the present application with unnecessary or redundant details. Therefore, the specific structural and functional details described herein are not intended to be limiting, but rather serve merely as a basis and representative basis for the claims to teach those skilled in the art to variously utilize the present application with substantially any suitable detailed structure.

[0103] This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," which may all refer to one or more of the same or different embodiments according to the present application.

[0104] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.

Claims

1. An overvoltage and undervoltage protection circuit, characterized in that: It includes a reference voltage module, an undervoltage threshold control module, an undervoltage hysteresis control module, an overvoltage threshold control module, an overvoltage hysteresis control module, a logic control module and a switch control module, wherein: The positive input terminal of the reference voltage module is electrically connected to the positive electrode of the power supply, the negative input terminal of the reference voltage module is electrically connected to the negative electrode of the power supply and the negative electrode of the input voltage, and the output terminal of the reference voltage module is electrically connected to the first input terminal of the undervoltage hysteresis control module and the first input terminal of the overvoltage hysteresis control module, respectively; the power input terminal of the undervoltage threshold control module is electrically connected to the positive and negative electrodes of the input voltage, the output terminal of the undervoltage threshold control module is electrically connected to the second input terminal of the undervoltage hysteresis control module, and the output terminal of the undervoltage hysteresis control module is electrically connected to the hysteresis input terminal of the undervoltage threshold control module and the first input terminal of the logic control module, respectively; The power input end of the overvoltage threshold control module is electrically connected to the positive and negative poles of the input voltage, the output end of the overvoltage threshold control module is electrically connected to the second input end of the overvoltage hysteresis control module, the first output end of the overvoltage hysteresis control module is electrically connected to the second input end of the logic control module, and the second output end of the overvoltage hysteresis control module is electrically connected to the hysteresis input end of the overvoltage threshold control module; the output end of the logic control module is electrically connected to the input end of the switch control module, and the output end of the switch control module is electrically connected to the negative output end of the protection circuit; the positive pole of the input voltage is electrically connected to the positive output end of the protection circuit.

2. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: The reference voltage module includes a first resistor, a second resistor, a third resistor and a voltage stabilizing chip, wherein: The first end of the third resistor is electrically connected to the positive electrode of the power supply, the second end of the third resistor is electrically connected to the input voltage pin of the voltage stabilizing chip, the ground pin of the voltage stabilizing chip is electrically connected to the negative electrode of the power supply and the negative electrode of the input voltage, the output end of the voltage stabilizing chip is electrically connected to the first end of the second resistor, the second end of the second resistor is electrically connected to the first end of the first resistor, the first input end of the undervoltage hysteresis control module and the first input end of the overvoltage hysteresis control module respectively, and the second end of the first resistor is electrically connected to the negative electrode of the input voltage.

3. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: The undervoltage threshold control module includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and a first MOS transistor, wherein: A first end of the sixth resistor is electrically connected to the positive electrode of the input voltage, a second end of the sixth resistor is electrically connected to the first end of the fifth resistor and the first end of the seventh resistor, respectively, a second end of the fifth resistor is electrically connected to the first end of the fourth resistor, the source of the first MOS transistor, and the second input end of the undervoltage hysteresis control module, and a second end of the fourth resistor is electrically connected to the negative electrode of the input voltage; a gate of the first MOS transistor is electrically connected to the output end of the undervoltage hysteresis control module, and a drain of the first MOS transistor is electrically connected to the second end of the seventh resistor.

4. The over-voltage and under-voltage protection circuit according to claim 3, characterized in that: The undervoltage hysteresis control module includes an eighth resistor, a ninth resistor and a first comparator, wherein: The negative input terminal of the first comparator is electrically connected to the output terminal of the reference voltage module, the positive input terminal of the first comparator is electrically connected to the second end of the fifth resistor, the first end of the fourth resistor, and the source of the first MOS transistor, respectively; the output terminal of the first comparator is electrically connected to the first end of the ninth resistor and the first end of the eighth resistor, respectively; the second end of the eighth resistor is electrically connected to the gate of the first MOS transistor; the output terminal of the first comparator is also electrically connected to the first input terminal of the logic control module through the tenth resistor; the second end of the ninth resistor is electrically connected to the positive electrode of the power supply.

5. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: The overvoltage threshold control module includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor and a second MOS transistor, wherein: The first end of the thirteenth resistor is electrically connected to the positive electrode of the input voltage, the second end of the thirteenth resistor is electrically connected to the first end of the twelfth resistor and the first end of the fourteenth resistor respectively, the second end of the twelfth resistor is electrically connected to the first end of the eleventh resistor, the source of the second MOS transistor and the second input end of the overvoltage hysteresis control module respectively, and the second end of the eleventh resistor is electrically connected to the negative electrode of the input voltage; the gate of the second MOS transistor is electrically connected to the second output end of the overvoltage hysteresis control module, and the drain of the second MOS transistor is electrically connected to the second end of the fourteenth resistor.

6. The over-voltage and under-voltage protection circuit according to claim 5, characterized in that: The overvoltage hysteresis control module includes a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a third MOS transistor and a second comparator, wherein: The positive input terminal of the second comparator is electrically connected to the output terminal of the reference voltage module, the negative input terminal of the second comparator is electrically connected to the second end of the twelfth resistor, the first end of the eleventh resistor, and the source of the second MOS transistor respectively, the output terminal of the second comparator is electrically connected to the first end of the seventeenth resistor and the first end of the sixteenth resistor respectively, the second end of the sixteenth resistor is electrically connected to the gate of the third MOS transistor, the drain of the third MOS transistor is electrically connected to the gate of the second MOS transistor and the first end of the fifteenth resistor respectively, and the source of the third MOS transistor is electrically connected to the negative electrode of the input voltage; the output terminal of the second comparator is also electrically connected to the second input terminal of the logic control module through the eighteenth resistor; the second end of the seventeenth resistor and the second end of the fifteenth resistor are both electrically connected to the positive electrode of the power supply.

7. The over-voltage and under-voltage protection circuit according to claim 1, characterized in that: The logic control module includes an AND gate logic unit and an inverter, wherein: The first input end of the AND gate logic unit is electrically connected to the output end of the undervoltage hysteresis control module, the second input end of the AND gate logic unit is electrically connected to the output end of the overvoltage hysteresis control module, the power input end of the AND gate logic unit is electrically connected to the positive and negative poles of the power supply, the output end of the AND gate logic unit is electrically connected to the data input end of the inverter, the positive input end of the inverter is electrically connected to the positive pole of the power supply, the negative input end of the inverter is electrically connected to the negative pole of the input voltage, and the output end of the inverter is electrically connected to the input end of the switch control module.

8. The over-voltage and under-voltage protection circuit according to claim 7, characterized in that: The AND gate logic unit includes a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a fourth MOS transistor and a fifth MOS transistor, and the inverter includes a sixth MOS transistor and a seventh MOS transistor, wherein: The gate of the fourth MOS transistor is electrically connected to the output end of the undervoltage hysteresis control module and the first end of the 20th resistor, respectively; the drain of the fourth MOS transistor is electrically connected to the source of the fifth MOS transistor; the source of the fourth MOS transistor and the second end of the 20th resistor are both electrically connected to the negative electrode of the input voltage; the gate of the fifth MOS transistor is electrically connected to the first output end of the overvoltage hysteresis control module and the first end of the 19th resistor, respectively; the drain of the fifth MOS transistor is electrically connected to the gate of the sixth MOS transistor, the gate of the seventh MOS transistor, and the first end of the 21st resistor, respectively; the second end of the 21st resistor is electrically connected to the positive electrode of the power supply; and the second end of the 19th resistor is electrically connected to the negative electrode of the input voltage. The drain of the sixth MOS transistor is electrically connected to the source of the seventh MOS transistor and the input end of the switch control module respectively, the source of the sixth MOS transistor is electrically connected to the negative electrode of the input voltage; the drain of the seventh MOS transistor is electrically connected to the positive electrode of the power supply.

9. The over-voltage and under-voltage protection circuit according to any one of claims 1 to 8, characterized in that: The switch control module includes a twenty-second resistor, a twenty-third resistor, a diode and an eighth MOS tube, wherein: The first end of the twenty-third resistor is electrically connected to the output end of the logic control module and the cathode of the diode, respectively; the second end of the twenty-third resistor is electrically connected to the anode of the diode, the first end of the twenty-second resistor, and the gate of the eighth MOS transistor, respectively; the drain of the eighth MOS transistor is electrically connected to the negative output end of the protection circuit; the source of the eighth MOS transistor and the second end of the twenty-second resistor are both electrically connected to the negative electrode of the input voltage.

10. A lighting fixture, characterized in that: The lighting fixture includes the over-voltage and under-voltage protection circuit according to any one of claims 1 to 9.

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