Detection circuit and detection device

Abstract

The utility model discloses a detection circuit and a detection device, in the detection circuit, an undervoltage detection circuit receives a first input voltage of a voltage input circuit and a first reference voltage of a voltage reference circuit, and generates an undervoltage detection signal according to the first input voltage and the first reference voltage to judge whether an input undervoltage condition occurs. The overvoltage detection circuit receives a first input voltage and a second reference voltage of the voltage reference circuit, and generates an overvoltage detection signal according to the first input voltage and the second reference voltage so as to judge whether an input overvoltage condition occurs. The output circuit receives the undervoltage detection signal or the overvoltage detection signal and then generates a detection signal, and input overvoltage and undervoltage detection is carried out, so that the safety of the power supply system is improved. By adding fewer devices, overvoltage and undervoltage protection of the power supply system is realized, the design difficulty of input overvoltage and undervoltage detection is simplified, the practicability and convenience of the detection circuit are improved, and the use experience of a user on the detection circuit is improved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a detection circuit and a detection device. Background Art

[0002] In medium and high power DC-DC (Direct-Current to Direct-Current) power supply systems, the power supply must have over-voltage and under-voltage protection functions. When the input voltage is lower than the input under-voltage protection point, the power supply turns off the output voltage; when the input voltage returns to the input under-voltage recovery point, the power supply restarts. When the input voltage is higher than the over-voltage protection point, the power supply turns off the output voltage; when the input voltage returns to the input over-voltage recovery point, the power supply restarts. However, this will cause the input voltage to be at a critical point, resulting in frequent power on and off. In order to avoid this, the usual practice is to set a certain voltage hysteresis between power on and off.

[0003] At present, the input over-voltage and under-voltage protection function of the power supply system is mainly realized by software detection. The software compares the detected input voltage with the set threshold voltage to control the switch of the system, and adds the hysteresis voltage judgment in the software program. For example, when the input voltage is lower than the set threshold voltage of the input under-voltage protection point, the power supply turns off the output voltage; when the input voltage increases to higher than the input under-voltage recovery point, the power supply restarts. However, in this process, after the software detects the input voltage, it needs to transmit the input voltage to the control unit. The control unit compares the input voltage with the threshold voltage set by the software to perform the input over-voltage and under-voltage protection function and the hysteresis voltage setting. Therefore, it is highly dependent on software programmers. In addition, if the control unit is selected to control only the input over-voltage and under-voltage protection function, only two interfaces of the control unit (input voltage detection interface and output signal interface) need to be occupied, and the control unit resources are wasted. Utility Model Content

[0004] The present application provides a detection circuit to solve the above technical problems. The detection circuit comprises:

[0005] A voltage reference circuit, used for generating a first reference voltage and a second reference voltage;

[0006] A voltage input circuit, used for generating a first input voltage;

[0007] an undervoltage detection circuit, wherein a first end of the undervoltage detection circuit is connected to the voltage input circuit to receive the first input voltage, and a second end of the undervoltage detection circuit is connected to the voltage reference circuit to receive the first reference voltage, and is used to generate an undervoltage detection signal according to the first input voltage and the first reference voltage;

[0008] an overvoltage detection circuit, wherein a first end of the overvoltage detection circuit is connected to the voltage reference circuit to receive the second reference voltage, and a second end of the overvoltage detection circuit is connected to the voltage input circuit to receive the first input voltage, and is used to generate an overvoltage detection signal according to the first input voltage and the second reference voltage;

[0009] The output circuit is connected to the third end of the undervoltage detection circuit and the third end of the overvoltage detection circuit respectively, receives the undervoltage detection signal or the overvoltage detection signal, and generates a detection signal.

[0010] Wherein, the undervoltage detection circuit includes a first comparator, a first resistor and a first diode, the first input end of the first comparator is connected to the voltage input circuit for receiving the first input voltage; the second input end of the first comparator is connected to the voltage reference circuit for receiving the first reference voltage, the first input end of the first comparator is connected to the output end of the first comparator through the first resistor and the first diode, and the output end of the first comparator is connected to the output circuit.

[0011] In which, the overvoltage detection circuit includes a second comparator, a second resistor, a third resistor and a second diode, the second input terminal of the second comparator is connected to the voltage input circuit for receiving the first input voltage; the first input terminal of the second comparator is connected to the voltage reference circuit through the second resistor for receiving the second reference voltage, the first input terminal of the second comparator is connected to the output terminal of the second comparator through the third resistor and the second diode, and the output terminal of the second comparator is connected to the output circuit.

[0012] The first input voltage is within a preset normal operating voltage range, the output end of the first comparator and the output end of the second comparator output a first level, and the detection signal output by the output circuit is a second level.

[0013] Among them, the first input voltage is within a preset overvoltage range, the output end of the second comparator outputs a second level, the output end of the first comparator is an open drain output, and the detection signal output by the output circuit is a first level.

[0014] Among them, the first input voltage is within a preset undervoltage range, the output end of the first comparator outputs a second level, the output end of the second comparator is an open drain output, and the detection signal output by the output circuit is a second level.

[0015] Wherein, the voltage reference circuit comprises:

[0016] Reference voltage source;

[0017] a fourth resistor, one end of which is connected to the positive electrode of the reference voltage source;

[0018] a fifth resistor, one end of the fifth resistor being connected to the other end of the fourth resistor, and the other end of the fifth resistor being connected to the negative electrode of the reference voltage source;

[0019] A first capacitor, one end of the first capacitor is connected to one end of the fifth resistor, and the other end of the first capacitor is connected to the other end of the fifth resistor.

[0020] Wherein, the voltage input circuit comprises:

[0021] a sixth resistor, one end of which receives a second input voltage;

[0022] a seventh resistor, one end of the seventh resistor being connected to the other end of the sixth resistor, and the other end of the seventh resistor being grounded;

[0023] A second capacitor, one end of the second capacitor is connected to one end of the seventh resistor, and the other end of the second capacitor is grounded.

[0024] Wherein, the output circuit comprises:

[0025] A photoelectric coupler, wherein the first end of the photoelectric coupler receives the first voltage through an eighth resistor, the second end of the photoelectric coupler is connected to the output end of the first comparator to receive the undervoltage detection signal, the second end of the photoelectric coupler is connected to the output end of the second comparator to receive the overvoltage detection signal, the third end of the photoelectric coupler receives the second voltage through a ninth resistor, and the fourth end of the photoelectric coupler generates the detection signal.

[0026] In order to solve the above technical problems, the present application also provides a detection device, which includes a control chip and the detection circuit as described above, the control chip is connected to the detection circuit, receives the detection signal, and controls the detection device based on the detection signal.

[0027] Beneficial effects of the present application: Different from the prior art, the detection circuit of the present application includes a voltage reference circuit, a voltage input circuit, an undervoltage detection circuit, an overvoltage detection circuit and an output circuit. The undervoltage detection circuit receives the first input voltage of the voltage input circuit and the first reference voltage of the voltage reference circuit, and generates an undervoltage detection signal according to the first input voltage and the first reference voltage to determine whether an input undervoltage occurs. The overvoltage detection circuit receives the first input voltage and the second reference voltage of the voltage reference circuit, and generates an overvoltage detection signal according to the first input voltage and the second reference voltage to determine whether an input overvoltage occurs. The output circuit generates a detection signal after receiving the undervoltage detection signal or the overvoltage detection signal, performs input over- and undervoltage detection, and improves the safety of the power supply system. By adding fewer devices, the over- and undervoltage protection of the power supply system is realized, wherein the design of the input over- and undervoltage and hysteresis parameters can be directly obtained by the user through calculation, which simplifies the design difficulty of the detection circuit, improves the practicality and convenience of the detection circuit, and enhances the user's experience of using the detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in 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 creative work.

[0029] in:

[0030] Figure 1 It is a structural schematic diagram of the first embodiment of the detection circuit of the present application.

[0031] Reference numerals: detection circuit 1; voltage reference circuit 11; voltage input circuit 12; undervoltage detection circuit 13; overvoltage detection circuit 14; output circuit 15. DETAILED DESCRIPTION

[0032] The scheme of the embodiment of the present application is described in detail below in conjunction with the drawings of the specification.

[0033] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0034] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the objects associated before and after are in an "or" relationship. In addition, "many" in this article means two or more than two. In addition, the term "at least one" in this article means any combination of at least two of any one or more of a plurality of, for example, including at least one of A, B, and C, and can mean including any one or more elements selected from the set consisting of A, B, and C. In addition, the terms "first", "second", and "third" in this application are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features.

[0036] See also Figure 1 , Figure 1 The detection circuit 1 provided in the embodiment of the present application comprises a voltage reference circuit 11 , a voltage input circuit 12 , an undervoltage detection circuit 13 , an overvoltage detection circuit 14 and an output circuit 15 .

[0037] The voltage reference circuit 11 is used to generate a first reference voltage and a second reference voltage; the voltage input circuit 12 is used to generate a first input voltage.

[0038] The first end of the undervoltage detection circuit 13 is connected to the voltage input circuit 12 to receive the first input voltage; the second end of the undervoltage detection circuit 13 is connected to the voltage reference circuit 11 to receive the first reference voltage, and then the undervoltage detection circuit 13 generates an undervoltage detection signal according to the first input voltage and the first reference voltage. In one embodiment, the undervoltage detection signal can be a high / low level signal. For example, when the input voltage Vin is in the undervoltage range, the undervoltage detection signal output by the undervoltage detection circuit 13 can be a low level, and when the input voltage Vin is greater than the undervoltage range and is in the normal voltage range, the undervoltage detection signal output by the undervoltage detection circuit 13 can be a high level.

[0039] The first end of the overvoltage detection circuit 14 is connected to the voltage reference circuit 11 to receive the second reference voltage transmitted by the voltage reference circuit 11, and the second end of the overvoltage detection circuit 14 is connected to the voltage input circuit 12 to receive the first input voltage, and is used to generate an overvoltage detection signal according to the first input voltage and the second reference voltage. In one example, the overvoltage detection signal can be a high / low level signal. For example, when the input voltage Vin is in the overvoltage range, the overvoltage detection signal output by the overvoltage detection circuit 13 can be a low level, and when the input voltage Vin is less than the overvoltage range and is in the normal voltage range, the overvoltage detection signal output by the overvoltage detection circuit 14 can be a high level.

[0040] The output circuit 15 is connected to the third end of the undervoltage detection circuit 13 and the third end of the overvoltage detection circuit 14, respectively, receives the undervoltage detection signal or the overvoltage detection signal, and generates a detection signal. In one embodiment, the detection signal can also be a high / low level signal. When the input voltage Vin is in an undervoltage state or an overvoltage state, that is, when the undervoltage detection signal is at a low level or the overvoltage detection signal is at a low level, the detection signal output by the output circuit 15 is a high level; and when the input voltage Vin is in a normal voltage range, that is, when the undervoltage detection signal is at a high level and the overvoltage detection signal is also at a high level, the detection signal output by the output circuit 15 is a low level.

[0041] The detection circuit 1 provided in the embodiment of the present application has a simple circuit structure, and can implement undervoltage and overvoltage testing of the input voltage Vin through simple devices. It only needs to sample the input voltage Vin once to obtain the first input voltage, and the circuit has high reliability. At the same time, according to the high / low level of the detection signal, it can quickly determine whether the input voltage Vin is in the undervoltage range, overvoltage range or normal voltage range, and then the power supply system can be protected from undervoltage and overvoltage in time, thereby improving the practicality of the detection circuit 1.

[0042] Optionally, the undervoltage detection circuit 13 includes a first comparator U1, a first resistor R1 and a first diode D1, the first input terminal (pin 1) of the first comparator U1 is connected to the voltage input circuit 12 for receiving a first input voltage; the second input terminal (pin 2) of the first comparator U1 is connected to the voltage reference circuit 11 for receiving a first reference voltage; the first input terminal of the first comparator U1 is connected to the output terminal (pin 3) of the first comparator U1 through the first resistor R1 and the first diode D1, and the output terminal of the first comparator U1 is connected to the output circuit 15.

[0043] Specifically, when the input voltage Vin is in the undervoltage range, the first input voltage received by the first input terminal of the first comparator U1 is lower than the first reference voltage received by the second input terminal of the first comparator U1. At this time, the undervoltage detection signal output by the output terminal of the first comparator U1 to the output circuit 15 is low level, indicating that the input voltage Vin is undervoltage. When the input voltage Vin is in the normal voltage range, the first input voltage received by the first input terminal of the first comparator U1 is higher than the first reference voltage received by the second input terminal of the first comparator U1. At this time, the undervoltage detection signal output by the output terminal of the first comparator U1 to the output circuit 15 is high level, indicating that the input voltage Vin is in the normal voltage range.

[0044] Optionally, the overvoltage detection circuit 14 includes a second comparator U2, a second resistor R2, a third resistor R3 and a second diode D2. The first input terminal (pin 4) of the second comparator U2 is connected to the voltage reference circuit 11 through the second resistor R2, for receiving the second reference voltage; the second input terminal (pin 5) of the second comparator U2 is connected to the voltage input circuit 12, for receiving the first input voltage; the first input terminal of the second comparator U2 is connected to the output terminal (pin 6) of the second comparator U2 through the third resistor R3 and the second diode D2, and the output terminal of the second comparator is connected to the output circuit 15.

[0045] Specifically, when the input voltage Vin is in the overvoltage range, the first input voltage received by the first input terminal of the second comparator U2 is higher than the second reference voltage received by the second input terminal of the second comparator U2, and at this time, the overvoltage detection signal output by the output terminal of the second comparator U2 to the output circuit 15 is low level, indicating that the input voltage Vin is overvoltage. When the input voltage Vin is in the normal voltage range, the first input voltage received by the first input terminal of the second comparator U2 is lower than the second reference voltage received by the second input terminal of the second comparator U2, and at this time, the overvoltage detection signal output by the output terminal of the second comparator U2 to the output circuit 15 is high level, indicating that the input voltage Vin is in the normal voltage range.

[0046] Optionally, the voltage reference circuit 11 includes a reference voltage source Vref, a fourth resistor R4, a fifth resistor R5 and a first capacitor C1.

[0047] One end of the fourth resistor R4 is connected to the positive electrode of the reference voltage source Vref, one end of the fifth resistor R5 is connected to the other end of the fourth resistor R4, and the other end of the fifth resistor R5 is connected to the negative electrode of the reference voltage source Vref. One end of the first capacitor C1 is connected to one end of the fifth resistor R5, and the other end of the first capacitor C1 is connected to the other end of the fifth resistor R5, so as to filter the voltage reference circuit 11 and ensure the stability of the current.

[0048] Specifically, after the devices in the voltage reference circuit 11 are connected as described above, the first reference voltage can be expressed as R5 / (R4+R5)*Vref, and since the first input terminal of the second comparator U2 is connected to the reference voltage source Vref through the second resistor R2, the second reference voltage can be expressed as Vref.

[0049] Optionally, the voltage input circuit 12 includes a sixth resistor R6, a seventh resistor R7 and a second capacitor C2, and one end of the sixth resistor R6 receives the second input voltage. Figure 1 The input voltage Vin shown, one end of the seventh resistor R7 is connected to the other end of the sixth resistor R6, and the other end of the seventh resistor R7 is grounded. One end of the second capacitor C2 is connected to one end of the seventh resistor R7, and the other end of the second capacitor C2 is grounded.

[0050] Furthermore, the output circuit 15 includes a photocoupler U3.

[0051] The first end of the photocoupler U3 receives the first voltage Vcc1 through the eighth resistor R8, the second end of the photocoupler U3 is connected to the output end of the first comparator U1 to receive the undervoltage detection signal transmitted by the first comparator U1, and the second end of the photocoupler U3 is also connected to the output end of the second comparator U2 to receive the overvoltage detection signal transmitted by the second comparator U2; the third end of the photocoupler U3 receives the second voltage Vcc2 through the ninth resistor R9, and the fourth section of the photocoupler U3 generates a detection signal. In one embodiment, the second voltage Vcc2 is 3.3V.

[0052] The following briefly describes the operation steps of the undervoltage detection circuit 13 and the overvoltage detection circuit 14 after receiving the first input voltage, the first reference voltage and the second reference voltage:

[0053] In this embodiment, the first level is a high level, and the second level is a low level.

[0054] When the first input voltage is within the preset normal working voltage range, that is, when the input voltage Vin is within the normal voltage range, the first comparator U1 outputs the first level, and the second comparator U2 also outputs the first level. At this time, the second end of the photoelectric coupler U3 is at a high level, and the photoelectric coupler U3 is cut off. At this time, the detection signal output by the photoelectric coupler U3 is at the second level. That is, in the present application, when the input voltage Vin is within the normal voltage range, the detection signal output by the output circuit 15 is at the second level.

[0055] When the first input voltage is within a preset overvoltage range, that is, the input voltage Vin is overvoltage, the output end of the second comparator U2 outputs a second level, and then the second end of the photoelectric coupler U3 is at a low level, the first voltage Vcc1 flows into the photoelectric coupler U3, the photoelectric coupler U3 is turned on, and the second voltage Vcc2 flows from the third end of the photoelectric coupler U3 to the fourth end of the photoelectric coupler U3, that is, at this time, the detection signal outputted from the fourth end of the photoelectric coupler U3 is at a high level.

[0056] At the same time, since the first input voltage is overvoltage, the first input voltage received by the first input terminal of the first comparator U1 is much larger than the first reference voltage received by the second input terminal of the first comparator U1, and the first comparator U1 opens the drain output. It can be considered that the connection between the first comparator U1 and the second terminal of the photocoupler U3 is broken.

[0057] When the output terminal of the second comparator U2 outputs the second level (low level), since the output terminal of the second comparator U2 is connected to the first input terminal of the second comparator U2 through the third resistor R3 and the second diode D2, the second reference voltage will become smaller, and the second reference voltage can be expressed as R3 / (R3+R2)*(Vref-0.3V)+0.3V, where 0.3V is the voltage drop of the second diode D2. When the first input voltage gradually decreases to the normal voltage range, the voltage of the second input terminal of the second comparator U2 is less than the voltage of the first input terminal of the second comparator U2, the output terminal of the second comparator U2 outputs the first level, and the detection signal output by the fourth terminal of the photocoupler U3 is the second level.

[0058] In this process, the third resistor R3 and the second diode D2 are used to set the hysteresis voltage (backlash voltage) of the input overvoltage. That is, in this process, when the detection circuit 1 detects that the first input voltage is in the preset overvoltage range, after changing the detection signal from the second level to the first level, the voltage value of the second reference voltage is reduced to ensure that the first input voltage is reduced to a certain level before restoring the judgment of the input voltage Vin under-overvoltage, avoiding the situation where the detection circuit 1 frequently changes the detection signal due to the fluctuation of the first input voltage at the overvoltage point. Improve the accuracy of the detection circuit 1 in judging the overvoltage of the input voltage Vin, and improve the reliability and safety of the detection circuit 1.

[0059] When the first input voltage is in a preset undervoltage range, that is, the input voltage Vin is undervoltage, the first comparator U1 outputs a second level, and then the second end of the photoelectric coupler U3 is at a low level, the first voltage Vcc1 flows into the photoelectric coupler U3, the photoelectric coupler U3 is turned on, and the second voltage Vcc2 flows from the third end of the photoelectric coupler U3 to the fourth end of the photoelectric coupler U3, that is, at this time, the detection signal outputted from the fourth end of the photoelectric coupler U3 is at a high level.

[0060] At the same time, since the first input voltage is undervoltage, the first input voltage received by the first input terminal of the second comparator U2 is much smaller than the second reference voltage received by the second input terminal of the second comparator U2, and the second comparator U2 opens the drain output. It can be considered that the connection between the second comparator U2 and the second end of the photocoupler U3 is broken.

[0061] When the output terminal of the first comparator U1 outputs the second level (low level), since the output terminal of the first comparator U1 is connected to the first input terminal of the first comparator U1 through the first resistor R1 and the first diode D1, the first input voltage will become smaller, and the first input voltage can be expressed as (R1 / / R7) / ((R1 / / R7)+R6)*Vin, where (R1 / / R7)=R1*R7 / (R1+R7), and the voltage drop of the first diode D1 is too small compared with the input voltage Vin, so it is ignored here. When the first input voltage gradually decreases to the normal voltage range, when the voltage of the second input terminal of the first comparator U1 is less than the voltage of the first input terminal of the first comparator U1, the output terminal of the first comparator U1 outputs the first level, and the detection signal output by the fourth terminal of the photocoupler U3 is the second level.

[0062] In this process, the first resistor R1 and the first diode D1 are used to set the hysteresis voltage (backlash voltage) of the input undervoltage. That is, in this process, when the detection circuit 1 detects that the first input voltage is in the preset undervoltage range, after changing the detection signal from the second level to the first level, the voltage value of the first input voltage sampled from the input voltage Vin is reduced (the proportion of the first input voltage to the input voltage Vin is reduced) to ensure that the judgment of the input voltage Vin under-voltage or over-voltage is restored after the first input voltage rises to a certain level, avoiding the situation where the detection circuit 1 frequently changes the detection signal due to the fluctuation of the first input voltage at the undervoltage point. Improve the accuracy of the detection circuit 1 in judging the undervoltage of the input voltage Vin, and improve the reliability and safety of the detection circuit 1.

[0063] In summary, the present application provides a simple and reliable detection circuit 1 for detecting the over-voltage or under-voltage state of the input voltage Vin. The circuit structure is simple, which simplifies the difficulty for the user to detect the over-voltage or under-voltage state of the input voltage Vin. By setting the undervoltage detection circuit 13 to judge the undervoltage state of the input voltage Vin, and by setting the overvoltage detection circuit 14 to judge the overvoltage state of the input voltage Vin, the reliability and accuracy of the detection circuit 1 for detecting the over-voltage or under-voltage state of the input voltage Vin are improved. The voltage input circuit 12 only needs to sample the input voltage Vin once to obtain the first input voltage, which further improves the reliability of the detection circuit 1.

[0064] At the same time, in the circuit structure of the undervoltage detection circuit 13 and the overvoltage detection circuit 14, a hysteresis voltage setting for inputting over- and undervoltage is added, so as to avoid the fluctuation of the judgment of the detection circuit 1 when the input voltage Vin fluctuates near the over- and undervoltage point, thereby improving the stability and safety of the detection circuit 1.

[0065] The present application also provides a detection device (not shown), comprising a control chip and the detection circuit 1 as described above. The control chip is connected to the detection circuit 1, receives a detection signal output by the detection circuit 1, and controls the detection device based on the detection signal.

[0066] Among them, the control chip can be a control IC, an MCU (Microcontroller Unit) chip, a DSP (Digital Signal Process) chip, etc., and the detection circuit 1 can be connected to the enable pin of the control IC, the I / O port of the MCU chip or the DSP chip, and then transmit the detection signal to the control chip. As mentioned above, the detection signal can be a high / low level, that is, the control chip only needs to judge the high / low level of the detection signal to judge the voltage state of the input voltage Vin, which is simple and fast, and improves the efficiency and reliability of the detection device for detecting the voltage state of the input voltage Vin.

[0067] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A detection circuit, characterized in that: include: A voltage reference circuit, used to generate a first reference voltage and a second reference voltage; A voltage input circuit, used for generating a first input voltage; an undervoltage detection circuit, wherein a first end of the undervoltage detection circuit is connected to the voltage input circuit to receive the first input voltage, and a second end of the undervoltage detection circuit is connected to the voltage reference circuit to receive the first reference voltage, and is used to generate an undervoltage detection signal according to the first input voltage and the first reference voltage; an overvoltage detection circuit, wherein a first end of the overvoltage detection circuit is connected to the voltage reference circuit to receive the second reference voltage, and a second end of the overvoltage detection circuit is connected to the voltage input circuit to receive the first input voltage, and is used to generate an overvoltage detection signal according to the first input voltage and the second reference voltage; The output circuit is connected to the third end of the undervoltage detection circuit and the third end of the overvoltage detection circuit respectively, receives the undervoltage detection signal or the overvoltage detection signal, and generates a detection signal.

2. The detection circuit according to claim 1, characterized in that: The undervoltage detection circuit includes a first comparator, a first resistor and a first diode. The first input terminal of the first comparator is connected to the voltage input circuit for receiving the first input voltage. The second input terminal of the first comparator is connected to the voltage reference circuit for receiving the first reference voltage. The first input terminal of the first comparator is connected to the output terminal of the first comparator through the first resistor and the first diode, and the output terminal of the first comparator is connected to the output circuit.

3. The detection circuit according to claim 2, characterized in that: The overvoltage detection circuit includes a second comparator, a second resistor, a third resistor and a second diode. The second input terminal of the second comparator is connected to the voltage input circuit for receiving the first input voltage; the first input terminal of the second comparator is connected to the voltage reference circuit through the second resistor for receiving the second reference voltage, the first input terminal of the second comparator is connected to the output terminal of the second comparator through the third resistor and the second diode, and the output terminal of the second comparator is connected to the output circuit.

4. The detection circuit according to claim 3, characterized in that: The first input voltage is within a preset normal operating voltage range, the output end of the first comparator and the output end of the second comparator output a first level, and the detection signal output by the output circuit is a second level.

5. The detection circuit according to claim 3, characterized in that: The first input voltage is within a preset overvoltage range, the output terminal of the second comparator outputs a second level, the output terminal of the first comparator is an open-drain output, and the detection signal output by the output circuit is a first level.

6. The detection circuit according to claim 3, characterized in that: The first input voltage is within a preset undervoltage range, the output end of the first comparator outputs a second level, the output end of the second comparator is an open-drain output, and the detection signal output by the output circuit is a second level.

7. The detection circuit according to claim 1, characterized in that: The voltage reference circuit comprises: Reference voltage source; a fourth resistor, one end of which is connected to the positive electrode of the reference voltage source; a fifth resistor, one end of the fifth resistor being connected to the other end of the fourth resistor, and the other end of the fifth resistor being connected to the negative electrode of the reference voltage source; A first capacitor, one end of the first capacitor is connected to one end of the fifth resistor, and the other end of the first capacitor is connected to the other end of the fifth resistor.

8. The detection circuit according to claim 1, characterized in that: The voltage input circuit comprises: a sixth resistor, one end of which receives a second input voltage; a seventh resistor, one end of the seventh resistor being connected to the other end of the sixth resistor, and the other end of the seventh resistor being grounded; A second capacitor, one end of the second capacitor is connected to one end of the seventh resistor, and the other end of the second capacitor is grounded.

9. The detection circuit according to claim 3, characterized in that: The output circuit comprises: A photoelectric coupler, wherein the first end of the photoelectric coupler receives the first voltage through an eighth resistor, the second end of the photoelectric coupler is connected to the output end of the first comparator to receive the undervoltage detection signal, the second end of the photoelectric coupler is connected to the output end of the second comparator to receive the overvoltage detection signal, the third end of the photoelectric coupler receives the second voltage through a ninth resistor, and the fourth end of the photoelectric coupler generates the detection signal.

10. A detection device, characterized in that: The detection device comprises a control chip and the detection circuit according to any one of claims 1 to 9, wherein the control chip is connected to the detection circuit, receives the detection signal, and controls the detection device based on the detection signal.

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