Overvoltage protection circuit, intrinsic safety circuit and explosion-proof lamp

Abstract

The utility model discloses an overvoltage protection circuit, an intrinsically safe circuit and an explosion-proof lamp, and relates to the technical field of explosion-proof of electric equipment, when the voltage of a power supply is normal, comparators in a first comparison circuit and a second comparison circuit output low-level signals, a first switch and a second switch are conducted, and a load works normally. When the power supply voltage abnormally rises, the comparators in the first comparison circuit and the second comparison circuit output high-level signals, the first switch and the second switch are cut off, and the load stops working. According to the overvoltage protection circuit, when the power supply voltage abnormally rises, the comparison circuit controls the switch to be switched off, the current is not switched on, the function of protecting the circuit is achieved, meanwhile, excessive energy and heat energy are prevented from being generated when the circuit breaks down, and explosion accidents are prevented. The overvoltage protection circuit is applied to the intrinsically safe circuit, so that the rated power required by a voltage stabilizing diode in the intrinsically safe circuit can be reduced, and the power of a single-path load can be increased.

Description

Technical Field

[0001] The utility model relates to the technical field of explosion-proof of electrical equipment, in particular to an overvoltage protection circuit, an intrinsically safe circuit and an explosion-proof lamp. Background Art

[0002] Even if a short circuit or electric spark occurs in the circuit, it is not enough to ignite the surrounding flammable and explosive gases. Such a circuit is called an intrinsically safe circuit, or overvoltage protection circuit for short.

[0003] Due to the presence of flammable gases and dust in special places such as petrochemical platforms, gas stations, oil pump rooms, and coal mines, electrical equipment working in such environments must be explosion-proof. When the energy released in a circuit installed in an explosive gas environment is higher than a certain critical value, it will ignite the surrounding explosive gas. For safety reasons, the equipment in these special places needs to have the specified safety and explosion-proof characteristics, and constrain various electrical parameters in the electronic circuit. At the same time, it is required to adopt necessary protection measures to limit the spark energy and heat energy generated when the circuit fails to prevent the occurrence of explosion accidents. The circuit that meets the requirements is called an overvoltage protection circuit.

[0004] Traditional intrinsically safe circuits only have voltage stabilization and current limiting parts, and the voltage stabilization diodes required in intrinsically safe circuits have relatively high power. If the voltage stabilization and / or current limiting parts fail or the power supply voltage is unstable, the voltage may suddenly rise. Excessive voltage will affect the performance of the circuit and there is a risk of burning out the circuit. The energy and heat released by excessive voltage may also detonate gas and dust in the environment. Utility Model Content

[0005] The purpose of the utility model is to provide an overvoltage protection circuit, an intrinsically safe circuit and an explosion-proof lamp, which are connected in series with a controllable switch of the load. When the power supply voltage rises abnormally, the control switch is cut off, which not only plays a role in protecting the circuit, but also prevents excessive energy and heat from being generated when a circuit fails.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] An aspect of an embodiment of the utility model provides an overvoltage protection circuit, the overvoltage protection circuit comprising: a comparison circuit, the comparison circuit comprising a voltage divider circuit, a first voltage stabilizing circuit and a comparator, the input end of the voltage divider circuit and the input end of the first voltage stabilizing circuit are both connected to the positive pole of a power supply, the output end of the voltage divider circuit is connected to the in-phase input end of the comparator, and the output end of the first voltage stabilizing circuit is connected to the inverting input end of the comparator; a switch, the control end of the switch is connected to the output end of the comparator, the first electrode of the switch is connected to the negative pole of the load, the positive pole of the load is connected to the positive pole of the power supply, and the second electrode of the switch is grounded.

[0008] In some embodiments, the first voltage stabilizing circuit includes a first resistor and a voltage stabilizing device, one end of the first resistor is connected to the positive electrode of a power supply, the other end of the first resistor is connected to a first electrode of the voltage stabilizing device and an inverting input terminal of the comparator, and a second electrode of the voltage stabilizing device is grounded.

[0009] In some embodiments, the voltage divider circuit includes a second resistor and a third resistor, one end of the second resistor is connected to the positive electrode of a power supply, the other end of the second resistor is connected to one end of the third resistor and the non-inverting input terminal of the comparator, and the other end of the third resistor is grounded.

[0010] In some embodiments, the first voltage stabilizing circuit further includes a fourth resistor and a first capacitor, one end of the fourth resistor is connected to the first electrode of the voltage stabilizing device, the other end of the fourth resistor is connected to the second electrode of the voltage stabilizing device, and the first capacitor is connected in parallel with the fourth resistor.

[0011] In some embodiments, the comparison circuit also includes a first voltage zener diode, a second capacitor and an eleventh resistor, the power supply input terminal of the comparator is connected to one end of the eleventh resistor, the negative electrode of the first voltage zener diode and one end of the second capacitor, the ground terminal of the comparator, the positive electrode of the first voltage zener diode and the other end of the second capacitor are all grounded, and the other end of the eleventh resistor is connected to the positive electrode of the power supply.

[0012] In some embodiments, the switch adopts a first switch, and the first switch includes a PMOS tube, a first NPN transistor, a second NPN transistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor, the source of the PMOS tube and one end of the seventh resistor are connected to the negative electrode of the load, the gate of the PMOS tube is connected to the other end of the seventh resistor and one end of the sixth resistor, the other end of the sixth resistor is connected to the collector of the first NPN transistor, the base of the first NPN transistor is connected to one end of the eighth resistor and the collector of the second NPN transistor, the other end of the eighth resistor is connected to the positive electrode of the power supply, the base of the second NPN transistor is connected to the output end of the comparator through the fifth resistor, and the drain of the PMOS tube, the emitter of the first NPN transistor and the emitter of the second NPN transistor are all grounded.

[0013] In some embodiments, the switch adopts a second switch, the second switch includes an NMOS tube, a first NPN transistor, a fifth resistor and an eighth resistor, the drain of the NMOS tube is connected to the negative electrode of the load, the gate of the NMOS tube is connected to one end of the eighth resistor and the collector of the first NPN transistor, the other end of the eighth resistor is connected to the positive electrode of the power supply, the base of the first NPN transistor is connected to the output end of the comparator through the fifth resistor, and the source of the NMOS tube and the emitter of the first NPN transistor are both grounded.

[0014] One aspect of an embodiment of the utility model provides an intrinsically safe circuit, which includes at least two overvoltage protection circuits as described above, and a second voltage stabilizing circuit; the input end of the second voltage stabilizing circuit is connected to the positive pole of a power supply, the output end of the second voltage stabilizing circuit is respectively connected to at least two overvoltage protection circuits, and the load is connected in series with switches in at least two overvoltage protection circuits.

[0015] In some embodiments, at least two of the overvoltage protection circuits include a first overvoltage protection circuit and a second overvoltage protection circuit, the first overvoltage protection circuit includes a first comparison circuit and a first switch, the second overvoltage protection circuit includes a second comparison circuit and a second switch, the input end of the second voltage stabilizing circuit is connected to the positive pole of the power supply, and the output end of the second voltage stabilizing circuit is respectively connected to the first comparison circuit and the second comparison circuit; the output end of the second voltage stabilizing circuit, the first switch, the second switch, the load and the location are connected in series, the control end of the first switch is connected to the first comparison circuit, and the control end of the second switch is connected to the second comparison circuit.

[0016] In some embodiments, the second voltage stabilizing circuit includes a second voltage stabilizing diode, a third voltage stabilizing diode and a fuse, one end of the fuse is connected to the positive electrode of the power supply, the other end of the fuse is connected to the negative electrode of the second voltage stabilizing diode and the negative electrode of the third voltage stabilizing diode, the positive electrode of the second voltage stabilizing diode and the positive electrode of the third voltage stabilizing diode are grounded, and the other end of the fuse, the negative electrode of the second voltage stabilizing diode and the negative electrode of the third voltage stabilizing diode serve as the output end of the second voltage stabilizing circuit.

[0017] In some embodiments, the intrinsically safe circuit also includes a ninth resistor and a tenth resistor, one end of the tenth resistor is connected to one end of the ninth resistor and the output end of the second voltage stabilizing circuit, the other end of the tenth resistor is connected to the other end of the ninth resistor and the first electrode of the first switch, the second electrode of the first switch is connected to the positive electrode of the load, the negative electrode of the load is connected to the first electrode of the second switch, and the second electrode of the second switch is connected to the ground.

[0018] One aspect of an embodiment of the utility model provides an explosion-proof lamp, which includes the intrinsically safe circuit as described above.

[0019] According to an overvoltage protection circuit, an intrinsically safe circuit and an explosion-proof lamp according to the embodiment of the utility model, there are at least the following beneficial effects: the present application connects a controllable switch in series with a load. When the power supply voltage is normal, the comparison circuit controls the switch to be turned on, and the load works normally; when the power supply voltage rises abnormally, the comparison circuit controls the switch to be turned off, which not only plays a role in protecting the circuit, but also prevents excessive energy and heat energy from being generated when a circuit fails, thereby preventing the occurrence of explosion accidents. By adopting the overvoltage protection circuit of the present application, the traditional function of using a voltage regulator diode for overvoltage protection is replaced, thereby reducing the rated power required by the voltage regulator diode, and no longer needing to use a high-power voltage regulator diode, increasing the power that can be carried by a single channel, and greatly reducing the number of wiring connections of the explosion-proof lamp.

[0020] It is to be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a schematic diagram of an overvoltage protection circuit in some embodiments of the present application;

[0023] Figure 2 This is a schematic diagram of an intrinsically safe circuit according to some embodiments of the present application.

[0024] The description of the reference numerals is as follows: 1. comparison circuit; 11. first comparison circuit; 12. second comparison circuit; 101. voltage divider circuit; 102. first voltage stabilizing circuit; 2. switch; 21. first switch; 22. second switch; 3. second voltage stabilizing circuit. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] The terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present disclosure will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0029] When the voltage suddenly increases, the excessive voltage will affect the performance of the circuit and there is a risk of burning out the circuit.

[0030] In order to solve the above technical problems, the present application provides an overvoltage protection circuit, which disconnects the power supply when the voltage is too high to prevent the electronic components in the circuit from burning out.

[0031] The overvoltage protection circuit of the embodiment of the present application is briefly described below:

[0032] According to some embodiments, Figure 1 As shown, the present application provides an overvoltage protection circuit, the overvoltage protection circuit comprising:

[0033] Comparison circuit 1, the comparison circuit 1 includes a voltage divider circuit 101, a first voltage stabilizing circuit 102 and a comparator U, the input end of the voltage divider circuit 101 and the input end of the first voltage stabilizing circuit 102 are both connected to the positive electrode of the power supply, the output end of the voltage divider circuit 101 is connected to the non-inverting input end of the comparator U, and the output end of the first voltage stabilizing circuit 102 is connected to the inverting input end of the comparator U;

[0034] Switch 2, the control end of switch 2 is connected to the output end of comparator U, the first electrode of switch 2 is connected to the negative electrode of the load, the positive electrode of the load is connected to the positive electrode of the power supply, and the second electrode of switch 2 is grounded.

[0035] The switch 2 is configured to be turned on when the control end of the switch 2 receives a low-level signal, and to be turned off when the control end of the switch 2 receives a high-level signal.

[0036] The working principle based on the above embodiment is as follows: Figure 1 As shown, the load and the comparison circuit 1 are connected to the positive pole of the same power supply, and the comparison circuit 1 and the switch 2 are connected to the same power supply. When the power supply voltage is normal, the voltage output by the first voltage stabilizing circuit 102 is higher than the voltage output by the voltage divider circuit 101, resulting in the voltage at the inverting input terminal of the comparator U being higher than the voltage at the non-inverting input terminal of the comparator U, the comparator U outputs a low-level signal, the switch 2 is turned on, the current passes, and the load works normally. When the power supply voltage rises abnormally, the voltage output by the first voltage stabilizing circuit 102 is lower than the voltage output by the voltage divider circuit 101, resulting in the voltage at the inverting input terminal of the comparator U being lower than the voltage at the non-inverting input terminal of the comparator U, the comparator U outputs a high-level signal, the switch 2 is turned off, the current does not pass, and the load stops working.

[0037] When the power supply voltage of the overvoltage protection circuit of the present application rises abnormally, the comparison circuit 1 controls the switch 2 to be cut off, and the current does not flow, which not only protects the circuit, but also prevents the generation of excessive energy and heat energy when a circuit fails, thereby preventing the occurrence of explosion accidents.

[0038] The following is combined with the appendix of this manual Figure 1 to Figure 2 , the overvoltage protection circuit of the present application is further elaborated in detail.

[0039] According to some embodiments, Figure 1 As shown, the voltage at the inverting input terminal of the comparator U should be stabilized within a range as a reference voltage, so the first voltage stabilizing circuit 102 of the present application is used for voltage stabilization. The first voltage stabilizing circuit 102 includes a first resistor R1 and a voltage stabilizing device. One end of the first resistor R1 is connected to the positive electrode of the power supply, and the other end of the first resistor R1 is connected to the first electrode of the voltage stabilizing device and the inverting input terminal of the comparator U. The second electrode of the voltage stabilizing device is grounded.

[0040] In some preferred embodiments, the voltage stabilizing device is TL431, and in other embodiments, the voltage stabilizing device may also be a voltage stabilizing diode, which is not limited in the present application.

[0041] The voltage regulator uses TL431, such as Figure 1As shown, one end of the first resistor R1 is connected to the positive electrode of the power supply, the other end of the first resistor R1 is connected to the cathode of the voltage stabilizing device, the reference end of the voltage stabilizing device and the inverting input end of the comparator U, and the anode of the voltage stabilizing device is grounded.

[0042] Further, such as Figure 1 As shown, the first voltage stabilizing circuit 102 further includes a fourth resistor R4 and a first capacitor C1, one end of the fourth resistor R4 is connected to the cathode of TL431, the other end of the fourth resistor R4 is connected to the anode of TL431, and the first capacitor C1 is connected in parallel with the fourth resistor R4.

[0043] The first resistor R1 is used for current limiting, TL431 is used for voltage stabilization, and the fourth resistor R4 and the first capacitor C1 are used for resistance-capacitance filtering.

[0044] According to some embodiments, Figure 1 As shown, the voltage divider circuit 101 includes a second resistor R2 and a third resistor R3, one end of the second resistor R2 is connected to the positive electrode of the power supply, the other end of the second resistor R2 is connected to one end of the third resistor R3 and the non-inverting input terminal of the comparator U, and the other end of the third resistor R3 is grounded. The voltage value of the non-inverting input terminal of the comparator U can be changed by changing the resistance value of the second resistor R2 and / or the third resistor R3.

[0045] According to some embodiments, Figure 1 As shown, the comparison circuit 1 also includes a first voltage zener diode Z1, a second capacitor C2 and an eleventh resistor R11, the power input end of the comparator U is connected to one end of the eleventh resistor R11, the cathode of the first voltage zener diode Z1 and one end of the second capacitor C2, the ground end of the comparator U, the anode of the first voltage zener diode Z1 and the other end of the second capacitor C2 are all grounded, and the other end of the eleventh resistor R11 is connected to the positive electrode of the power supply.

[0046] The first voltage stabilizing diode Z1 is used to stabilize the voltage input to the VDD pin of the comparator U, and the second capacitor C2 is used to filter the voltage input to the VDD pin of the comparator U.

[0047] In some embodiments, Figure 2As shown, the switch 2 adopts a first switch 21, and the first switch 21 includes a PMOS tube QP, a first NPN transistor NPN1, a second NPN transistor NPN2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8. The source of the PMOS tube QP and one end of the seventh resistor R7 are connected to the negative electrode of the load, the gate of the PMOS tube QP is connected to the other end of the seventh resistor R7 and one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to the collector of the first NPN transistor NPN1, the base of the first NPN transistor NPN1 is connected to one end of the eighth resistor R8 and the collector of the second NPN transistor NPN2, the other end of the eighth resistor R8 is connected to the positive electrode of the power supply, the base of the second NPN transistor NPN2 is connected to the output end of the comparator U through the fifth resistor R5, and the drain of the PMOS tube QP, the emitter of the first NPN transistor NPN1 and the emitter of the second NPN transistor NPN2 are all grounded.

[0048] Among them, Figure 2 As shown, the other end of the eighth resistor R8 is connected to one end of the eleventh resistor R11, the cathode of the first voltage zener diode Z1 and one end of the second capacitor C2.

[0049] Based on the working principle of the above embodiment, when the power supply voltage is normal, the voltage output by the first voltage stabilizing circuit 102 is higher than the voltage output by the voltage divider circuit 101, resulting in the voltage at the inverting input terminal of the comparator U being higher than the voltage at the non-inverting input terminal of the comparator U, and the comparator U outputs a low-level signal. The base of the second NPN transistor NPN2 receives the low-level signal, and the second NPN transistor NPN2 is cut off. The base of the first NPN transistor NPN1 receives a high-level signal through the eighth resistor R8, and the first NPN transistor NPN1 is turned on. The gate of the PMOS tube QP receives a low-level signal through the first NPN transistor NPN1, and the PMOS tube QP is turned on.

[0050] When the power supply voltage rises abnormally, the voltage output by the first voltage stabilizing circuit 102 is lower than the voltage output by the voltage divider circuit 101, causing the voltage at the inverting input terminal of the comparator U to be lower than the voltage at the non-inverting input terminal of the comparator U. The comparator U outputs a high-level signal, the base of the second NPN transistor NPN2 receives the high-level signal, the second NPN transistor NPN2 is turned on, the base of the first NPN transistor NPN1 receives a low-level signal through the second NPN transistor NPN2, the first NPN transistor NPN1 is turned off, the gate of the PMOS tube QP receives a high-level signal through the seventh resistor R7, and the PMOS tube QP is turned off.

[0051] In other embodiments, Figure 2As shown, in addition to the first switch 21, the switch 2 may also use a second switch 22, the second switch 22 includes an NMOS tube QN, a first NPN transistor NPN1, a fifth resistor R5 and an eighth resistor R8, the drain of the NMOS tube QN is connected to the negative electrode of the load, the gate of the NMOS tube QN is connected to one end of the eighth resistor R8 and the collector of the first NPN transistor NPN1, the other end of the eighth resistor R8 is connected to the positive electrode of the power supply, the base of the first NPN transistor NPN1 is connected to the output end of the comparator U through the fifth resistor R5, and the source of the NMOS tube QN and the emitter of the first NPN transistor NPN1 are both grounded.

[0052] Among them, Figure 2 As shown, the other end of the eighth resistor R8 is connected to one end of the eleventh resistor R11, the cathode of the first voltage zener diode Z1 and one end of the second capacitor C2.

[0053] Based on the working principle of the above embodiment, when the power supply voltage is normal, the voltage output by the first voltage stabilizing circuit 102 is higher than the voltage output by the voltage divider circuit 101, resulting in the voltage at the inverting input terminal of the comparator U being higher than the voltage at the non-inverting input terminal of the comparator U, and the comparator U outputs a low-level signal. The base of the first NPN transistor NPN1 receives the low-level signal, the first NPN transistor NPN1 is turned off, and the gate of the NMOS tube QN receives a high-level signal through the eighth resistor R8, and the NMOS tube QN is turned on.

[0054] When the power supply voltage rises abnormally, the voltage output by the first voltage stabilizing circuit 102 is lower than the voltage output by the voltage divider circuit 101, causing the voltage at the inverting input terminal of the comparator U to be lower than the voltage at the non-inverting input terminal of the comparator U. The comparator U outputs a high-level signal, the base of the first NPN transistor NPN1 receives the high-level signal, the first NPN transistor NPN1 is turned on, the gate of the NMOS transistor QN receives the low-level signal through the first NPN transistor NPN1, and the NMOS transistor QN is turned off.

[0055] Furthermore, in addition to the first switch 21 and the second switch 22 in the above-mentioned embodiment, the switch 2 may also adopt a circuit switching device with power-on and power-off functions or an electronic component with power-on and power-off functions, such as a relay, an IGBT, a thyristor, etc., which is not limited in the present application.

[0056] Traditional intrinsically safe circuits only have voltage stabilization and current limiting parts. However, if the voltage stabilization and / or current limiting parts fail or the power supply voltage is unstable, the voltage may suddenly rise. Excessive voltage will affect the performance of the circuit and there is a risk of burning out the circuit. In addition, the energy and heat released by excessive voltage may detonate gas and dust in the environment.

[0057] In order to solve the above technical problems, the present application provides an intrinsically safe circuit, which not only plays the role of protecting the circuit, but also prevents the generation of excessive energy and heat energy when the circuit fails, thereby preventing the occurrence of explosion accidents.

[0058] The intrinsically safe circuit of the embodiment of the present application is described below:

[0059] According to some embodiments, Figure 2 As shown, the present application provides an intrinsically safe circuit, which includes at least two overvoltage protection circuits as described above, and a second voltage stabilizing circuit 3;

[0060] The input end of the second voltage stabilizing circuit 3 is connected to the positive electrode of the power supply, the output end of the second voltage stabilizing circuit 3 is respectively connected to at least two overvoltage protection circuits, and the load is connected in series with switches in at least two overvoltage protection circuits.

[0061] Among them, Figure 2 As shown, in some embodiments, at least two overvoltage protection circuits include a first overvoltage protection circuit and a second overvoltage protection circuit, and the first overvoltage protection circuit and the second overvoltage protection circuit both include a comparison circuit 1 with the same structure, and then the first overvoltage protection circuit and the second overvoltage protection circuit can be provided with a first switch 21 with the same structure, or a second switch 22 with the same structure, or a first switch 21 and a second switch 22 with different structures can be provided in the first overvoltage protection circuit and the second overvoltage protection circuit respectively. The load is connected in series with the switches in the first overvoltage protection circuit and the second overvoltage protection circuit.

[0062] In some specific embodiments, Figure 2 As shown, the first overvoltage protection circuit includes a first comparison circuit 11 and a first switch 21, the second overvoltage protection circuit includes a second comparison circuit 12 and a second switch 22, the input end of the second voltage stabilizing circuit 3 is connected to the positive electrode of the power supply, and the output end of the second voltage stabilizing circuit 3 is connected to the first comparison circuit 11 and the second comparison circuit 12 respectively;

[0063] The output end of the second voltage stabilizing circuit 3 , the first switch 21 , the second switch 22 , the load and the ground are connected in series. The control end of the first switch 21 is connected to the first comparison circuit 11 , and the control end of the second switch 22 is connected to the second comparison circuit 12 .

[0064] The structures of the comparison circuit 1 , the first comparison circuit 11 and the second comparison circuit 12 are the same.

[0065] Based on the working principle of the above embodiment, when the power supply voltage is normal, the comparators U in the first comparison circuit 11 and the second comparison circuit 12 both output low-level signals, the first switch 21 and the second switch 22 are both turned on, and the load works normally.

[0066] When the power supply voltage increases abnormally, the comparators U in the first comparison circuit 11 and the second comparison circuit 12 both output high-level signals, the first switch 21 and the second switch 22 are both turned off, and the load stops working.

[0067] When the power supply voltage of the overvoltage protection circuit of the present application rises abnormally, the comparison circuit controls the switch to be cut off and the current does not flow, which not only protects the circuit, but also prevents the generation of excessive energy and heat energy when a circuit fails, thereby preventing the occurrence of explosion accidents.

[0068] According to some embodiments, Figure 2 As shown, the second voltage stabilizing circuit 3 includes at least two voltage stabilizing diodes and a fuse F. In some embodiments, the at least two voltage stabilizing diodes include a second voltage stabilizing diode Z2 and a third voltage stabilizing diode Z3. One end of the fuse F is connected to the positive electrode of the power supply, and the other end of the fuse F is connected to the negative electrode of the second voltage stabilizing diode Z2 and the negative electrode of the third voltage stabilizing diode Z3. The positive electrode of the second voltage stabilizing diode Z2 and the positive electrode of the third voltage stabilizing diode Z3 are grounded. The other end of the fuse F, the negative electrode of the second voltage stabilizing diode Z2 and the negative electrode of the third voltage stabilizing diode Z3 serve as the output end of the second voltage stabilizing circuit 3.

[0069] The fuse F is used to fuse and cut off the current when the current abnormally rises to a certain height and temperature, so as to protect the safe operation of the circuit. The second voltage stabilizing diode Z2 and the third voltage stabilizing diode Z3 are used to stabilize the voltage.

[0070] After the first overvoltage protection circuit and the second overvoltage protection circuit are adopted in the present application, the traditional function of using a Zener diode for overvoltage protection is replaced, so that a high-power Zener diode is not needed in the second voltage stabilizing circuit 3. By adopting the overvoltage protection circuit of the present application, the rated power required for the Zener diode is reduced, the power that a single channel can carry is increased, and the number of wiring connections of the explosion-proof lamp is greatly reduced.

[0071] According to some embodiments, Figure 2 As shown, the intrinsically safe circuit also includes a ninth resistor R9 and a tenth resistor R10, one end of the tenth resistor R10 is connected to one end of the ninth resistor R9 and the output end of the second voltage stabilizing circuit 3, the other end of the tenth resistor R10 is connected to the other end of the ninth resistor R9 and the first electrode of the first switch 21, the second electrode of the first switch 21 is connected to the positive electrode of the load, the negative electrode of the load is connected to the first electrode of the second switch 22, and the second electrode of the second switch 22 is connected to the ground.

[0072] The ninth resistor R9 and the tenth resistor R10 are used for current limiting protection.

[0073] According to some embodiments, Figure 2As shown, the present application provides an explosion-proof lamp, which includes the intrinsically safe circuit as described above, and an LED lamp. The load can be replaced by an LED lamp.

[0074] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0075] Although the present disclosure has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present disclosure can be implemented in a variety of forms without departing from the spirit or essence of the present application, it should be understood that the above-mentioned embodiments are not limited to any of the foregoing details, but should be widely interpreted within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An overvoltage protection circuit, characterized in that: The overvoltage protection circuit comprises: A comparison circuit, wherein the comparison circuit comprises a voltage divider circuit, a first voltage stabilizing circuit and a comparator, wherein an input end of the voltage divider circuit and an input end of the first voltage stabilizing circuit are both connected to a positive electrode of a power supply, an output end of the voltage divider circuit is connected to a non-inverting input end of the comparator, and an output end of the first voltage stabilizing circuit is connected to an inverting input end of the comparator; A switch, wherein the control end of the switch is connected to the output end of the comparator, the first electrode of the switch is connected to the negative electrode of the load, the positive electrode of the load is connected to the positive electrode of the power supply, and the second electrode of the switch is grounded.

2. The overvoltage protection circuit according to claim 1, characterized in that: The first voltage stabilizing circuit includes a first resistor and a voltage stabilizing device, one end of the first resistor is connected to the positive electrode of a power supply, the other end of the first resistor is connected to the first electrode of the voltage stabilizing device and the inverting input end of the comparator, and the second electrode of the voltage stabilizing device is grounded.

3. The overvoltage protection circuit according to claim 1, characterized in that: The voltage divider circuit includes a second resistor and a third resistor, one end of the second resistor is connected to the positive electrode of the power supply, the other end of the second resistor is connected to one end of the third resistor and the non-inverting input end of the comparator, and the other end of the third resistor is grounded.

4. The overvoltage protection circuit according to claim 2, characterized in that: The first voltage stabilizing circuit also includes a fourth resistor and a first capacitor, one end of the fourth resistor is connected to the first electrode of the voltage stabilizing device, the other end of the fourth resistor is connected to the second electrode of the voltage stabilizing device, and the first capacitor is connected in parallel with the fourth resistor.

5. The overvoltage protection circuit according to claim 1, characterized in that: The comparison circuit also includes a first voltage-stabilizing diode, a second capacitor and an eleventh resistor. The power supply input terminal of the comparator is connected to one end of the eleventh resistor, the negative electrode of the first voltage-stabilizing diode and one end of the second capacitor. The ground terminal of the comparator, the positive electrode of the first voltage-stabilizing diode and the other end of the second capacitor are all grounded. The other end of the eleventh resistor is connected to the positive electrode of the power supply.

6. The overvoltage protection circuit according to claim 1, characterized in that: The switch adopts a first switch, which includes a PMOS tube, a first NPN transistor, a second NPN transistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor. The source of the PMOS tube and one end of the seventh resistor are connected to the negative electrode of the load, the gate of the PMOS tube is connected to the other end of the seventh resistor and one end of the sixth resistor, the other end of the sixth resistor is connected to the collector of the first NPN transistor, the base of the first NPN transistor is connected to one end of the eighth resistor and the collector of the second NPN transistor, the other end of the eighth resistor is connected to the positive electrode of the power supply, the base of the second NPN transistor is connected to the output end of the comparator through the fifth resistor, and the drain of the PMOS tube, the emitter of the first NPN transistor and the emitter of the second NPN transistor are all grounded.

7. The overvoltage protection circuit according to claim 1, characterized in that: The switch adopts a second switch, and the second switch includes an NMOS tube, a first NPN transistor, a fifth resistor and an eighth resistor. The drain of the NMOS tube is connected to the negative electrode of the load, the gate of the NMOS tube is connected to one end of the eighth resistor and the collector of the first NPN transistor, the other end of the eighth resistor is connected to the positive electrode of the power supply, the base of the first NPN transistor is connected to the output end of the comparator through the fifth resistor, and the source of the NMOS tube and the emitter of the first NPN transistor are both grounded.

8. An intrinsically safe circuit, characterized in that: The intrinsically safe circuit comprises at least two overvoltage protection circuits as claimed in any one of claims 1 to 7, and a second voltage stabilization circuit; The input end of the second voltage stabilizing circuit is connected to the positive electrode of the power supply, the output end of the second voltage stabilizing circuit is respectively connected to at least two overvoltage protection circuits, and the load is connected in series with switches in the at least two overvoltage protection circuits.

9. The intrinsically safe circuit according to claim 8, characterized in that: At least two of the overvoltage protection circuits include a first overvoltage protection circuit and a second overvoltage protection circuit, the first overvoltage protection circuit includes a first comparison circuit and a first switch, the second overvoltage protection circuit includes a second comparison circuit and a second switch, the input end of the second voltage stabilizing circuit is connected to the positive electrode of the power supply, and the output end of the second voltage stabilizing circuit is connected to the first comparison circuit and the second comparison circuit respectively; The output end of the second voltage stabilizing circuit, the first switch, the second switch, a load and a location are connected in series, the control end of the first switch is connected to the first comparison circuit, and the control end of the second switch is connected to the second comparison circuit.

10. The intrinsically safe circuit according to claim 8, characterized in that: The second voltage stabilizing circuit includes a second voltage stabilizing diode, a third voltage stabilizing diode and a fuse, one end of the fuse is connected to the positive electrode of the power supply, the other end of the fuse is connected to the negative electrode of the second voltage stabilizing diode and the negative electrode of the third voltage stabilizing diode, the positive electrode of the second voltage stabilizing diode and the positive electrode of the third voltage stabilizing diode are grounded, and the other end of the fuse, the negative electrode of the second voltage stabilizing diode and the negative electrode of the third voltage stabilizing diode serve as the output end of the second voltage stabilizing circuit.

11. The intrinsically safe circuit according to claim 9, characterized in that: The intrinsically safe circuit also includes a ninth resistor and a tenth resistor, one end of the tenth resistor is connected to one end of the ninth resistor and the output end of the second voltage stabilizing circuit, the other end of the tenth resistor is connected to the other end of the ninth resistor and the first electrode of the first switch, the second electrode of the first switch is connected to the positive electrode of the load, the negative electrode of the load is connected to the first electrode of the second switch, and the second electrode of the second switch is connected to the ground.

12. An explosion-proof lamp, characterized in that: The explosion-proof lamp comprises the intrinsically safe circuit as described in any one of claims 8 to 10.

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