Input voltage overvoltage and undervoltage detection circuit

Abstract

The utility model discloses an input voltage overvoltage undervoltage detection circuit, which comprises a rectification voltage division module, a control module, a comparison module and a reference voltage circuit, the rectification voltage division module is electrically connected with the comparison module and the control module, and the comparison module is electrically connected with the reference voltage circuit and the control module. The input end of the rectifying and voltage-dividing module is connected with the alternating current input end, the comparison module comprises two comparison circuits, and the input end of one comparison circuit is connected with the first reference voltage end of the reference voltage circuit and the output end of the rectifying and voltage-dividing module; the input end of the other comparison circuit is connected with the second reference voltage end of the reference voltage circuit and the output end of the rectification and voltage division module, and the output ends of the two comparison circuits are electrically connected with the control module after being connected. The comparison module of the input voltage overvoltage and undervoltage detection circuit comprises two comparison circuits which are respectively connected with the first reference voltage end and the second reference voltage end of the reference voltage circuit so as to respectively carry out overvoltage detection and undervoltage detection.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits, in particular to an input voltage overvoltage and undervoltage detection circuit. Background Art

[0002] In most traditional switching power supplies, the input voltage is not detected. The power supply still works when the voltage is too low or too high, causing damage to the power supply and even the equipment connected to the power supply. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide an input voltage overvoltage and undervoltage detection circuit to perform overvoltage detection and undervoltage detection on the input voltage.

[0004] To solve the above technical problems, the purpose of the utility model is achieved through the following technical solutions: to provide an input voltage overvoltage and undervoltage detection circuit, including a rectifier and voltage divider module, a control module, a comparison module and a reference voltage circuit, the rectifier and voltage divider module is electrically connected to the comparison module and the control module, the comparison module is electrically connected to the reference voltage circuit and the control module, the input end of the rectifier and voltage divider module is connected to the AC input end, the comparison module includes two comparison circuits, wherein the input end of one comparison circuit is connected to the first reference voltage end of the reference voltage circuit and the output end of the rectifier and voltage divider module, the input end of the other comparison circuit is connected to the second reference voltage end of the reference voltage circuit and the output end of the rectifier and voltage divider module, and the output ends of the two comparison circuits are connected and electrically connected to the control module.

[0005] The beneficial technical effect of the utility model is that the input voltage overvoltage and undervoltage detection circuit of the utility model is convenient for subsequent input voltage comparison by setting a rectifier and voltage divider module connected to the AC input end, the comparison module and the control module so as to rectify and divide the input current according to the control of the control module and then output it to the comparison module. The comparison module is connected to the reference voltage circuit and the control module, and the comparison module includes two comparison circuits, one of which is connected to the first reference voltage end of the reference voltage circuit, and the other is connected to the second reference voltage end of the reference voltage circuit, so as to compare the received detection voltage signals output by the rectifier and voltage divider module according to the corresponding reference voltages, respectively, to realize overvoltage and undervoltage detection, and the output ends of the two comparison circuits are connected and electrically connected to the control module, so that when the control module confirms that the input voltage is abnormal in either the undervoltage detection or the overvoltage detection, the circuit operation can be adjusted, and the overvoltage detection and the undervoltage detection can be realized synchronously. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0007] Figure 1 A schematic diagram of the framework of an input voltage overvoltage and undervoltage detection circuit provided by an embodiment of the utility model;

[0008] Figure 2 A circuit diagram of a comparison module of an input voltage overvoltage and undervoltage detection circuit provided by an embodiment of the utility model;

[0009] Figure 3 A circuit diagram of a reference voltage circuit of an input voltage overvoltage and undervoltage detection circuit provided by an embodiment of the utility model;

[0010] Figure 4 A circuit diagram of a rectifier and voltage divider module of an input voltage overvoltage and undervoltage detection circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0011] 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 part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of 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.

[0012] See also Figures 1 to 4 , Figure 1 The framework schematic diagram of the input voltage overvoltage and undervoltage detection circuit provided by the embodiment of the utility model, the input voltage overvoltage and undervoltage detection circuit 10 includes a rectifier and voltage divider module 11, a control module 12, a comparison module 13 and a reference voltage circuit 14, the rectifier and voltage divider module 11 is electrically connected to the comparison module 13 and the control module 12, the comparison module 13 is electrically connected to the reference voltage circuit 14 and the control module 12, the input end of the rectifier and voltage divider module 11 is connected to the AC input end, the comparison module 13 includes two comparison circuits 131, wherein the input end of one of the comparison circuits 131 is connected to the first reference voltage end Vref1 of the reference voltage circuit 14 and the output end Vac of the rectifier and voltage divider module 11, the input end of the other comparison circuit 131 is connected to the second reference voltage end Vref2 of the reference voltage circuit 14 and the output end Vac of the rectifier and voltage divider module 11, and the output ends of the two comparison circuits 131 are connected and electrically connected to the control module 12.

[0013] The control module 12 includes an MCU, and the input voltage overvoltage and undervoltage detection circuit 10 is provided with a rectifier and voltage divider module 11 connected to the AC input terminal, the comparison module 13 and the control module 12, so that the input current can be rectified and divided according to the control of the control module 12 and then output to the comparison module 13, so as to facilitate subsequent input voltage comparison. The comparison module 13 is connected to the reference voltage circuit 14 and the control module 12, and the comparison module 13 includes two comparison circuits 131, wherein one comparison circuit 131 is connected to the first reference voltage terminal Vref1 of the reference voltage circuit 14, and the other comparison circuit 131 is connected to the second reference voltage terminal Vref2 of the reference voltage circuit 14, so as to compare the received detection voltage signals output by the rectifier and voltage divider module 11 according to the corresponding reference voltages, respectively, to realize overvoltage and undervoltage detection, and the output terminals of the two comparison circuits 131 are connected and then electrically connected to the control module 12, so that when the control module 12 confirms that the input voltage is abnormal in any of the undervoltage detection or the overvoltage detection, the circuit operation can be adjusted, and the overvoltage detection and the undervoltage detection can be realized synchronously.

[0014] Specifically, the comparison circuit 131 includes an operational amplifier, an output resistor and an output diode, the output end of the operational amplifier is connected to the anode of the output diode through the output resistor, the cathode of the output diode is connected to the control module 12, and the cathode of the output diode serves as the output end of the corresponding comparison circuit 131, wherein the in-phase input end and the in-phase input end of one of the operational amplifiers are respectively connected to the first reference voltage end Vref1 of the reference voltage circuit 14 and the output end Vac of the rectifier and voltage divider module 11, and the in-phase input end and the in-phase input end of the other operational amplifier are respectively connected to the output end Vac of the rectifier and voltage divider module 11 and the second reference voltage end Vref2 of the reference voltage circuit 14.

[0015] Specifically, if the voltage value corresponding to the first reference voltage terminal Vref1 of the reference voltage circuit 14 is less than the voltage value corresponding to the second reference voltage terminal Vref2 of the reference voltage circuit 14, the first reference voltage terminal Vref1 of the reference voltage circuit 14 may be an undervoltage reference voltage terminal, and the second reference voltage terminal Vref2 of the reference voltage circuit 14 may be an overvoltage reference voltage terminal. The comparison circuit 131 corresponding to the operational amplifier connected to the first reference voltage terminal Vref1 of the reference voltage circuit 14 serves as an undervoltage comparison circuit, and the comparison circuit 131 corresponding to the operational amplifier connected to the second reference voltage terminal Vref2 of the reference voltage circuit 14 serves as an overvoltage comparison circuit.

[0016] Preferably, the first reference voltage terminal Vref1 of the reference voltage circuit 14 is connected to the in-phase input terminal of the corresponding operational amplifier through the fifteenth resistor R15, and the inverting input terminal of the operational amplifier is connected to the output terminal Vac of the rectifier voltage divider module 11 through the thirteenth resistor R13, and the operational amplifier, the output resistor and the output diode are U2A, R11 and D3 respectively. The second reference voltage terminal Vref2 of the reference voltage circuit 14 is connected to the inverting input terminal of the corresponding operational amplifier through the fourteenth resistor R14, and the in-phase input terminal of the operational amplifier is connected to the output terminal Vac of the rectifier voltage divider module 11 through the sixteenth resistor R16, and the operational amplifier, the output resistor and the output diode are U2B, R12 and D4 respectively.

[0017] When the voltage outputted by the output terminal Vac of the rectifier voltage divider module 11 is less than the voltage value corresponding to the undervoltage reference voltage terminal, the output terminal of the operational amplifier U2B whose in-phase input terminal and in-phase input terminal are respectively connected to the output terminal Vac of the rectifier voltage divider module 11 and the second reference voltage terminal Vref2 of the reference voltage circuit 14 outputs a low level, and the overvoltage comparison circuit outputs a low level, while the output terminal of the operational amplifier U2A whose in-phase input terminal and in-phase input terminal are respectively connected to the output terminal Vac of the rectifier voltage divider module 11 and the first reference voltage terminal Vref1 of the reference voltage circuit 14 outputs a high level, and the undervoltage comparison circuit outputs a high level. level, the comparison module 13 outputs a high level to the control module 12. The control module 12 learns that the input voltage is abnormal based on the received high level, and then controls the entire circuit to stop working; when the voltage output by the output terminal Vac of the rectifier and voltage divider module 11 is greater than the voltage value corresponding to the overvoltage reference voltage terminal, the output terminal of the operational amplifier U2A whose inverting input terminal and the non-inverting input terminal are respectively connected to the output terminal Vac of the rectifier and voltage divider module 11 and the first reference voltage terminal Vref1 of the reference voltage circuit 14 outputs a low level, the undervoltage comparison circuit outputs a low level, and the non-inverting input terminal and the inverting input terminal are respectively connected to the output terminal Vac of the rectifier and voltage divider module 11 and the first reference voltage terminal Vref1 of the reference voltage circuit 14. The output terminal Vac of the block 11 and the output terminal of the operational amplifier U2B connected to the second reference voltage terminal Vref2 of the reference voltage circuit 14 outputs a high level, and the overvoltage comparison circuit outputs a high level, then the comparison module 13 outputs a high level to the control module 12, and the control module 12 learns that the input voltage is abnormal based on the received high level, and then controls the entire circuit to stop working; when the voltage output by the output terminal Vac of the rectifier and voltage divider module 11 is not less than the voltage value corresponding to the undervoltage reference voltage terminal and not greater than the voltage value corresponding to the overvoltage reference voltage terminal, the in-phase input terminal and the inverting input terminal are respectively connected to the voltage value of the rectifier and voltage divider module 11. The output end of the operational amplifier U2B connected to the output end Vac and the second reference voltage end Vref2 of the reference voltage circuit 14 outputs a low level, the overvoltage comparison circuit outputs a low level, and the output end of the operational amplifier U2A connected to the output end Vac of the rectifier voltage divider module 11 and the first reference voltage end Vref1 of the reference voltage circuit 14 of the inverting input end and the non-inverting input end respectively outputs a low level, the undervoltage comparison circuit outputs a low level, and the comparison module 13 outputs a low level to the control module 12. The control module 12 learns that the input voltage is normal based on the received low level, and can then control the circuit to continue to work normally.

[0018] Preferably, both the non-inverting input terminal and the inverting input terminal of the operational amplifier are connected in parallel with a grounding capacitor to filter the signal input to the operational amplifier.

[0019] Specifically, the reference voltage circuit 14 includes a voltage regulator U1, an eighth current limiting resistor R8, a ninth voltage dividing resistor R9 and a tenth voltage dividing resistor R10, the ninth voltage dividing resistor R9 and the tenth voltage dividing resistor R10 are connected in series, the first end of the ninth voltage dividing resistor R9 is respectively connected to the second end of the eighth current limiting resistor R8 and the cathode of the voltage regulator U1, the second end of the ninth voltage dividing resistor R9 is connected to the first end of the tenth voltage dividing resistor R10 and the reference electrode of the voltage regulator U1, the anode of the voltage regulator U1 and the second end of the tenth voltage dividing resistor R10 are both grounded, the cathode of the voltage regulator U1 serves as the second reference voltage terminal Vref2 of the reference voltage circuit 14, the reference electrode of the voltage regulator U1 serves as the first reference voltage terminal Vref1 of the reference voltage circuit 14, and the first end of the eighth current limiting resistor R8 is connected to the power supply voltage VCC.

[0020] Specifically, the voltage regulator U1 adopts a controllable precision voltage source of model TL431, which can set the voltage value range to 2.5V to 36V. The corresponding ninth voltage-dividing resistor R9 and the tenth voltage-dividing resistor R10 can be connected according to the actual situation to design the reference voltage value corresponding to the corresponding second reference voltage terminal Vref2, that is, the reference voltage value of the overvoltage reference voltage terminal of the reference voltage circuit 14 can be adjusted according to the actual situation, so that the input voltage overvoltage and undervoltage detection circuit 10 can perform overvoltage detection on a variety of voltages, which is highly practical. The reference voltage value corresponding to the reference pole of the voltage regulator U1 is 2.5V, and the reference voltage value of the undervoltage reference voltage terminal of the reference voltage circuit 14 is 2.5V.

[0021] Specifically, the rectifier and voltage divider module 11 includes a rectifier unit 111, a voltage divider unit 112 and a first switch tube Q1. The rectifier unit 111 is connected to the input end of the first switch tube Q1 through the voltage divider unit 112. The output end of the first switch tube Q1 serves as the output end of the rectifier and voltage divider module 11. The output end of the first switch tube Q1 is connected to the fourth grounding resistor R4 and the comparison module 13. The control end of the first switch tube Q1 is connected to the control pin Control of the control module 12 through the seventh resistor R7, so that the first switch tube Q1 is turned on or off according to the control of the control module 12 to control the on and off of the output of the rectifier and voltage divider module 11. The output end of the first switch tube Q1 is connected to the inverting input end of an operational amplifier U2A whose in-phase input end is electrically connected to the first reference voltage end Vref1 of the reference voltage circuit 14 and the inverting input end of an operational amplifier U2B whose inverting input end is electrically connected to the second reference voltage end Vref2 of the reference voltage circuit 14.

[0022] Specifically, the rectifier unit 111 includes a first diode D1 and a second diode D2, the anode of the first diode D1 is connected to the live wire L of the AC input terminal through a first resistor R1, the cathode of the first diode D1 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to the neutral wire N of the AC input terminal through a fifth resistor R5. The rectifier unit 111 is set to rectify the AC signal input from the AC input terminal into a DC signal. The rectifier unit 111 includes a first diode D1 and a second diode D2 connected to the live wire L and the neutral wire N, respectively, to achieve full-wave rectification. The resistance values ​​of the first resistor R1 and the fifth resistor R5 can be equal.

[0023] Specifically, the voltage dividing unit 112 includes a second voltage dividing resistor R2 and a third voltage dividing resistor R3 connected in series, wherein a first end of the second voltage dividing resistor R2 is connected to a cathode of the first diode D1 and a cathode of the second diode D2, a second end of the second voltage dividing resistor R2 is connected to a first end of the third voltage dividing resistor R3, and a second end of the third voltage dividing resistor R3 is connected to an input end of the first switch tube Q1. The voltage dividing unit 112 is provided to divide and limit the DC signal obtained after full-wave rectification.

[0024] Specifically, the first switch tube Q1 is an NMOS tube, the drain of the first switch tube Q1 is connected to the second end of the third voltage-dividing resistor R3, the source of the first switch tube Q1 is connected to the fourth grounding resistor R4 and the comparison module 13, the source of the first switch tube Q1 is also electrically connected to the first grounding capacitor C1 to filter the output signal of the output terminal Vac of the rectifier voltage-dividing module 11 to output a stable voltage signal to the comparison module 13 for comparison, the gate of the first switch tube Q1 is connected to the control pin Control of the control module 12 through the seventh resistor R7, and the sixth grounding resistor R6 is connected in parallel between the gate of the first switch tube Q1 and the seventh resistor R7. When the first switch tube Q1 is turned on, the second voltage-dividing resistor R2, the third voltage-dividing resistor R3 and the fourth grounding resistor R4 form a loop to divide the DC signal after full-wave rectification by the rectifier unit 111 and output it to the comparison module 13.

[0025] In summary, the input voltage overvoltage and undervoltage detection circuit of the utility model is provided with a rectifier and voltage divider module connected to the AC input terminal, the comparison module and the control module so that the input current can be rectified and divided according to the control of the control module and then output to the comparison module, so as to facilitate the subsequent input voltage comparison. The comparison module is connected to the reference voltage circuit and the control module, and the comparison module includes two comparison circuits, one of which is connected to the first reference voltage terminal of the reference voltage circuit, and the other is connected to the second reference voltage terminal of the reference voltage circuit, so as to compare the received detection voltage signals output by the rectifier and voltage divider module according to the corresponding reference voltages, respectively, to realize overvoltage and undervoltage detection, and the output terminals of the two comparison circuits are connected and electrically connected to the control module, so that when the control module confirms that the input voltage is abnormal in either the undervoltage detection or the overvoltage detection, the circuit operation can be adjusted, and the overvoltage detection and the undervoltage detection can be realized synchronously.

[0026] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. An input voltage overvoltage and undervoltage detection circuit, characterized in that: It includes a rectifier and voltage divider module, a control module, a comparison module and a reference voltage circuit. The rectifier and voltage divider module is electrically connected to the comparison module and the control module. The comparison module is electrically connected to the reference voltage circuit and the control module. The input end of the rectifier and voltage divider module is connected to the AC input end. The comparison module includes two comparison circuits, wherein the input end of one comparison circuit is connected to the first reference voltage end of the reference voltage circuit and the output end of the rectifier and voltage divider module, and the input end of the other comparison circuit is connected to the second reference voltage end of the reference voltage circuit and the output end of the rectifier and voltage divider module. The output ends of the two comparison circuits are connected and electrically connected to the control module.

2. The input voltage overvoltage and undervoltage detection circuit according to claim 1, characterized in that: The comparison circuit includes an operational amplifier, an output resistor and an output diode, wherein the output end of the operational amplifier is connected to the anode of the output diode through the output resistor, and the cathode of the output diode is connected to the control module, wherein the in-phase input end and the in-phase input end of one operational amplifier are respectively connected to the first reference voltage end of the reference voltage circuit and the output end of the rectifier and voltage divider module, and the in-phase input end and the in-phase input end of the other operational amplifier are respectively connected to the output end of the rectifier and voltage divider module and the second reference voltage end of the reference voltage circuit.

3. The input voltage overvoltage and undervoltage detection circuit according to claim 2, characterized in that: A voltage value corresponding to the first reference voltage terminal of the reference voltage circuit is smaller than a voltage value corresponding to the second reference voltage terminal of the reference voltage circuit.

4. The input voltage overvoltage and undervoltage detection circuit according to claim 2, characterized in that: The reference voltage circuit includes a voltage stabilizer, an eighth current limiting resistor, a ninth voltage dividing resistor and a tenth voltage dividing resistor. The ninth voltage dividing resistor and the tenth voltage dividing resistor are connected in series, the first end of the ninth voltage dividing resistor is respectively connected to the second end of the eighth current limiting resistor and the cathode of the voltage stabilizer, the second end of the ninth voltage dividing resistor is connected to the first end of the tenth voltage dividing resistor and the reference electrode of the voltage stabilizer, the anode of the voltage stabilizer and the second end of the tenth voltage dividing resistor are both grounded, the cathode of the voltage stabilizer serves as the second reference voltage terminal of the reference voltage circuit, the reference electrode of the voltage stabilizer serves as the first reference voltage terminal of the reference voltage circuit, and the first end of the eighth current limiting resistor is connected to the supply voltage.

5. The input voltage overvoltage and undervoltage detection circuit according to claim 4, characterized in that: The voltage stabilizer adopts a controllable precision voltage stabilizer of model TL431.

6. The input voltage overvoltage and undervoltage detection circuit according to claim 1, characterized in that: The rectifier and voltage divider module includes a rectifier unit, a voltage divider unit and a first switch tube. The rectifier unit is connected to the input end of the first switch tube through the voltage divider unit. The output end of the first switch tube serves as the output end of the rectifier and voltage divider module. The output end of the first switch tube is connected to a fourth grounding resistor and the comparison module. The control end of the first switch tube is connected to the control pin of the control module through a seventh resistor.

7. The input voltage overvoltage and undervoltage detection circuit according to claim 6, characterized in that: The rectifier unit includes a first diode and a second diode, the anode of the first diode is connected to the live wire of the AC input end through a first resistor, the cathode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is connected to the neutral wire of the AC input end through a fifth resistor.

8. The input voltage overvoltage and undervoltage detection circuit according to claim 7, characterized in that: The voltage-dividing unit includes a second voltage-dividing resistor and a third voltage-dividing resistor connected in series, wherein a first end of the second voltage-dividing resistor is connected to a cathode of the first diode and a cathode of the second diode, a second end of the second voltage-dividing resistor is connected to a first end of the third voltage-dividing resistor, and a second end of the third voltage-dividing resistor is connected to an input end of the first switching tube.

9. The input voltage overvoltage and undervoltage detection circuit according to claim 8, characterized in that: The first switch tube is an NMOS tube, the drain of the first switch tube is connected to the second end of the third voltage-dividing resistor, the source of the first switch tube is connected to the fourth grounding resistor and the comparison module, the gate of the first switch tube is connected to the control pin of the control module through the seventh resistor, and a sixth grounding resistor is connected in parallel between the gate of the first switch tube and the seventh resistor.

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