Protection device

Abstract

The utility model discloses a protection device, which is arranged between an input voltage and a load to be supplied with power, and comprises a voltage detection circuit of which the input end is connected with the input voltage and a switch control circuit of which the output end is connected with the load to be supplied with power, the switch control circuit at least comprises a first switch control circuit of which the input end is connected to the undervoltage detection circuit and a second switch control circuit of which the input end is connected to the overvoltage detection circuit; the output end of the first switch control circuit is connected to a power supply chip of a to-be-powered load, and the output end of the second switch control circuit is connected to a power supply loop of the to-be-powered load. The beneficial effects of the utility model are that the overvoltage and undervoltage states of the input voltage are detected at the same time and the power supply state of the to-be-powered load is correspondingly controlled, so that the to-be-powered load is ensured to operate only under normal voltage.

Description

Technical Field

[0001] The present application relates to the field of voltage detection, and in particular to a protection device. Background Art

[0002] When using the power supply, the mains voltage often drops or rises abnormally, or the electrician connects the wires incorrectly: if the input voltage drops (assuming the design is 220Vac, but the actual voltage drops to 150Vac or even lower), the output power of the power supply remains unchanged, the input voltage decreases, and the input current increases, resulting in transformer saturation and power loop failure;

[0003] If the input voltage increases (assuming the design is 220Vac, but it actually increases to 290Vac or even higher), the internal components of the power supply are designed for 220Vac±10%. At this time, if the voltage is too high, the internal components will be broken down, creating a risk of arcing.

[0004] like Figure 1 As shown, in the related technology, no matter how many V the input voltage is, it is rectified by BD, filtered by EC2 and directly enters R12 inside the power supply. The power supply starts working after detecting the voltage. When the voltage is abnormal and the input voltage exceeds the internal design value, the power supply will be damaged.

[0005] Chinese patent "An overvoltage protection circuit and a driver and power supply including the same", publication number: CN203690884U, publication date: July 2, 2014, discloses an overvoltage protection circuit and a driver and power supply including the same, the overvoltage protection circuit includes a first power input interface and a second power input interface connected to a rectifier power supply or a DC power supply; a soft start module including a soft start module input and a soft start module output coupled to the second power input interface: a soft start circuit branch connected between the soft start module input and the soft start module output and including a resistor element, and a normal operation circuit branch connected between the soft start module input and the soft start module output; a filter capacitor coupled between the first power input interface and the soft start module output; a circuit condition determiner, and an overvoltage detector. This scheme disconnects the input voltage when the input voltage is higher than the overvoltage threshold, but has no effect when undervoltage.

[0006] Chinese patent "An overvoltage protection circuit, charger and electronic device", publication number: CN109038529A, publication date: December 18, 2018, specifically discloses an overvoltage protection circuit, a charger and an electronic device, the overvoltage protection circuit includes: a first module, a second module and a third module, wherein the input end of the first module is connected to the input voltage, and the output end is connected to the input end of the second module; the output end of the second module is connected to the input end of the third module, used to control the third module to output a first voltage; the output end of the third module is connected to the working end of the working module, when the input voltage is greater than the preset voltage, the first voltage controls the working module to be in a non-working state. In this way, when the input voltage of the charger is too high, the working module in the charger is controlled to be in a non-working state through the overvoltage protection circuit, which can effectively avoid the problem that the charger is easily damaged when working under high voltage, and ensure the safety of the charger. When the input voltage of the charger is too high, this solution controls the working module in the charger to be in a non-working state through the overvoltage protection circuit, but it has no effect when the voltage is undervoltage. Utility Model Content

[0007] The utility model aims at the problem in the prior art that the load to be powered is easily damaged when the voltage is abnormal. A protection device is provided. By setting an undervoltage detection circuit and an overvoltage detection circuit, undervoltage detection and overvoltage detection are performed on the input voltage at the same time, so that the power supply can work normally only when the input voltage is within the set voltage range, thereby protecting the power supply from damage.

[0008] In order to achieve the above technical objectives, a technical solution provided by the utility model is a protection device, which is arranged between an input voltage and a load to be powered, comprising: a voltage detection circuit whose input end is connected to the input voltage and a switch control circuit whose output end is connected to the load to be powered, the voltage detection circuit at least includes an undervoltage detection circuit and an overvoltage detection circuit, the switch control circuit at least includes a first switch control circuit whose input end is connected to the undervoltage detection circuit and a second switch control circuit whose input end is connected to the overvoltage detection circuit; the output end of the first switch control circuit is connected to the power chip of the load to be powered, and the output end of the second switch control circuit is connected to the power supply circuit of the load to be powered.

[0009] Furthermore, the undervoltage detection circuit includes at least a first comparator, the first switch control circuit includes at least a first controller, the non-inverting input terminal of the first comparator is connected to a reference voltage, the inverting input terminal of the first comparator is connected to an input voltage, the first controller is connected between the first comparator and a power chip of a load to be powered, and the first comparator outputs a high or low level to control the on and off of the first controller to control the power supply state of the load to be powered.

[0010] Furthermore, the overvoltage detection circuit includes at least a second comparator, the second switch control circuit includes at least a second controller, the non-inverting input terminal of the second comparator is connected to the input voltage, the inverting input terminal of the second comparator is connected to the reference voltage, the second controller is connected between the input voltage and the power supply circuit of the load to be powered, and the second comparator outputs high and low levels to control the on and off of the second controller to control the power supply state of the load to be powered.

[0011] Furthermore, it also includes: a rectifier filter circuit arranged between the input voltage and the voltage detection circuit, the rectifier filter circuit at least includes a rectifier bridge and a first filter capacitor, the input voltage is connected to the input end of the rectifier bridge, and the first filter capacitor is connected in parallel to the output end of the rectifier bridge.

[0012] Furthermore, the undervoltage detection circuit includes: a first voltage-dividing resistor, a second voltage-dividing resistor, a first protection capacitor and a first comparator, one end of the first voltage-dividing resistor is connected to the live wire output end of the rectifier bridge, the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is connected to the zero line input end of the rectifier bridge, the first protection capacitor is connected in parallel to the second voltage-dividing resistor, the non-inverting input end of the first comparator is connected to the reference voltage, and the inverting input end of the first comparator is connected to the connection end of the first voltage-dividing resistor and the second voltage-dividing resistor.

[0013] Furthermore, the first switch control circuit includes: a first controller and a first bias resistor, the base of the first controller is connected to the output end of the first comparator, the collector of the first controller is connected to the voltage end of the power chip of the load to be powered, the emitter of the first controller is grounded, and the first bias resistor is connected to the base and emitter of the first controller.

[0014] Furthermore, the overvoltage detection circuit includes: a third voltage-dividing resistor, a fourth voltage-dividing resistor, a second protection capacitor and a second comparator, one end of the third voltage-dividing resistor is connected to the live wire output end of the rectifier bridge, the other end of the third voltage-dividing resistor is connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is connected to the zero line input end of the rectifier bridge, the first protection capacitor is connected in parallel to the fourth voltage-dividing resistor, and the in-phase input end of the second comparator is connected to the connection end of the third voltage-dividing resistor and the fourth voltage-dividing resistor.

[0015] Furthermore, the second switch control circuit includes: a second bias resistor, a second controller, a third controller, a third bias resistor, a first current limiting resistor and a second filter capacitor, the base of the third controller is connected to the output end of the second comparator, the emitter of the third controller is grounded, the second bias resistor is arranged between the emitter and the base of the third controller, the collector of the third controller is connected to the gate of the second controller and one end of the first current limiting resistor, the other end of the first current limiting resistor is connected to the positive power supply end of the second comparator, the source of the second controller is grounded, the drain of the second controller is connected to the negative electrode of the second filter capacitor, the positive electrode of the second filter capacitor is connected to the live wire output end of the rectifier bridge, and the load to be powered is connected in parallel to the second filter capacitor.

[0016] Furthermore, it also includes: a power supply protection circuit connected between the first switch control circuit and the load to be powered, the power supply protection circuit includes a pull-up resistor, a second current limiting resistor and a rectifier diode, one end of the pull-up resistor is connected to the collector of the first controller, the other end of the pull-up resistor is connected to the load to be powered, one end of the second current limiting resistor is connected to the live wire output end of the rectifier bridge, the other end of the second current limiting resistor is connected to the collector of the first controller, the positive electrode of the rectifier diode is connected to the emitter of the first controller, and the negative electrode of the rectifier diode is connected to the collector of the first controller.

[0017] Furthermore, it also includes: a reference setting circuit connected to the reference voltage input terminal of the voltage detection circuit, the reference setting circuit includes a protection resistor and a voltage regulator, one end of the protection resistor is connected to the power supply voltage terminal, the other end of the protection resistor is connected to the cathode of the voltage regulator, the anode of the voltage regulator is grounded, and the reference end of the voltage regulator is connected to the reference voltage input terminal.

[0018] The beneficial effects of the utility model are as follows: the undervoltage state and overvoltage state of the input voltage are judged simultaneously by the undervoltage circuit and the overvoltage detection circuit. When the input voltage is undervoltage, the undervoltage detection circuit controls the first switch control circuit to disconnect the circuit power supply state. When the input voltage is overvoltage, the overvoltage detection circuit controls the second switch control circuit to disconnect the circuit power supply state. Only when the input voltage is normal, the power supply circuit works normally. Therefore, the electrical appliance can be protected from damage in both the overvoltage state and the undervoltage state of the input voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a circuit diagram of a protection device in the related art.

[0020] Figure 2 The utility model is a circuit diagram of a protection device. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific implementation method described here is only an optimal embodiment of the utility model, which is only used to explain the utility model and does not limit the protection scope of the utility model. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0022] like Figure 2 As shown, as embodiment 1 of the present application, a protection device is arranged between an input voltage Vuvp and a load to be powered, comprising: a voltage detection circuit whose input end is connected to the input voltage and a switch control circuit whose output end is connected to the load to be powered, the voltage detection circuit at least comprises an undervoltage detection circuit and an overvoltage detection circuit, the switch control circuit at least comprises a first switch control circuit whose input end is connected to the undervoltage detection circuit and a second switch control circuit whose input end is connected to the overvoltage detection circuit; the output end of the first switch control circuit is connected to a power chip of the load to be powered, and the output end of the second switch control circuit is connected to the power supply circuit of the load to be powered.

[0023] In this embodiment, the input voltage Vuvp is the mains, that is, when a certain device or circuit needs to be powered, it is usually connected to the mains and powered by the mains. The undervoltage state and overvoltage state of the input voltage Vuvp are judged by the undervoltage circuit and the overvoltage detection circuit at the same time. When the input voltage Vuvp is undervoltage, the undervoltage detection circuit controls the first switch control circuit to disconnect the power supply state of the power chip to the load to be powered. At this time, the power chip does not work, and the load to be powered cannot obtain power. When the input voltage Vuvp is overvoltage, the overvoltage detection circuit controls the second switch control circuit to disconnect the power supply circuit of the load to be powered. At this time, the power supply circuit does not work, and the load to be powered cannot obtain power. Only when the input voltage Vuvp is normal, the power supply circuit works normally. Therefore, the electrical appliance can be protected from damage in both the overvoltage state and the undervoltage state of the input voltage Vuvp.

[0024] Specifically, the undervoltage detection circuit at least includes a first comparator A, the first switch control circuit at least includes a first controller Q1, the non-inverting input terminal of the first comparator A is connected to the reference voltage Vref, the inverting input terminal of the first comparator A is connected to the input voltage Vuvp, the first controller Q1 is connected between the first comparator A and the power chip of the load to be powered, and the first comparator A outputs a high or low level to control the on and off of the first controller Q1 to control the power supply state of the load to be powered. When the input voltage Vuvp is undervoltage, the undervoltage detection circuit controls the first switch control circuit to disconnect the power supply, including:

[0025] When the input voltage Vuvp is undervoltage and the first comparator A outputs a high level, the first controller Q1 is turned on, lowering the power supply voltage of the load to be powered and disconnecting the power supply.

[0026] The first controller Q1 can be any one of a triode, a field effect transistor (FET), and a bipolar junction transistor (BJT). In this embodiment, the first controller Q1 is an NPN triode, and the base of the first controller Q1 is connected to the output end of the first comparator A, the emitter of the first controller Q1 is grounded, and the collector of the first controller Q1 is connected to the power chip voltage Power-VCC of the load to be powered. When the input voltage Vuvp is input to the first comparator A, it is compared with the reference voltage Vref. When the input voltage Vuvp is less than the reference voltage Vref, the output end of the first comparator A outputs a high level, and when the input voltage Vuvp is greater than the reference voltage Vref, the output end of the first comparator A outputs a low level. Correspondingly, when the output terminal of the first comparator A outputs a high level, the base of the first controller Q1 receives the high level, the first controller Q1 is turned on, and the resistance between the collector and the emitter of the first controller Q1 becomes very small. Since the emitter of the first controller Q1 is grounded, the collector of the first controller Q1 is connected to the power chip voltage Power-VCC. Since the power supply of the load to be powered is a positive power supply, when the first controller Q1 is turned on, the collector level will be pulled down to close to the ground level. At this time, the power level of the load to be powered is pulled down, and the circuit does not work, thereby avoiding powering the load to be powered in an under-voltage state; when the output terminal of the first comparator A outputs a low level, the base of the first controller Q1 receives the low level, the first controller Q1 is turned off, and the collector voltage of the first controller Q1 is maintained at a high level, so that the power chip voltage Power-VCC of the load to be powered reaches the required voltage threshold to work and power the load to be powered.

[0027] In other embodiments, the first controller Q1 is an N-channel enhancement type MOS tube. At this time, the gate of the first controller Q1 is connected to the output end of the first comparator A. When the gate of the first controller Q1 receives a high level, the MOS tube is turned on, so that the resistance between the drain and the source becomes very small. When the source is grounded, the drain is connected to the power chip, and the level of the drain is pulled down to close to the ground level, so that the power chip cannot obtain the necessary working voltage, thereby avoiding supplying power to the load to be powered in an undervoltage state; when the gate of the first controller Q1 receives a low level, the MOS tube is turned off, and the drain is maintained at a high level state, so that the power chip voltage Power-VCC is in a high level state to work and supply power to the load to be powered.

[0028] The overvoltage detection circuit at least includes a second comparator B, the second switch control circuit at least includes a second controller Q3, the in-phase input terminal of the second comparator B is connected to the input voltage Vuvp, the inverting input terminal of the second comparator B is connected to the reference voltage Vref, the second controller Q3 is connected between the input voltage Vuvp and the power supply circuit of the load to be powered, and the second comparator B outputs a high or low level to control the on and off of the second controller Q3 to control the power supply state of the load to be powered. When the input voltage Vuvp is overvoltage, the overvoltage detection circuit controls the second switch control circuit to disconnect the power supply, including:

[0029] When the input voltage Vuvp is overvoltage, the second comparator B outputs a high level, and the second controller Q3 is disconnected, so that the power supply loop is disconnected and the power supply is cut off.

[0030] When the second controller Q3 is set as a switch between the input voltage Vuvp and the load to be powered, the AC live wire output can be connected to the second controller Q3, the second controller Q3 is connected to the load to be powered, and the load to be powered is grounded. At this time, the current output by the live wire can only flow through the load to be powered when the second controller Q3 is turned on. Once the second controller Q3 is turned off, the power supply circuit of the load to be powered is disconnected. Alternatively, the AC live wire output can be connected to the load to be powered, the load to be powered is connected to the second controller Q3, and the second controller Q3 is grounded. At this time, once the second controller Q3 is turned off, the current cannot return to the ground terminal or the neutral terminal, the circuit is disconnected, and the load to be powered cannot be powered.

[0031] The second controller Q3 can be a relay. If it is a normally open relay, when the second comparator B outputs a high level, the relay coil is energized, the contacts are closed, and the circuit is connected. When the second comparator B outputs a low level, the relay coil loses power, the contacts are disconnected, and the circuit is disconnected. If it is a normally closed relay, when the second comparator B outputs a high level, the relay contacts are disconnected, and the circuit is disconnected. When the second comparator B outputs a low level, the relay contacts are closed, and the circuit is connected. This realizes the control of the on and off of the power supply circuit.

[0032] It can be understood that, since both the in-phase input and the inverting input of the comparator can be connected to the input voltage Vuvp and the reference voltage Vref, but the high and low levels of the outputs are different under different connection conditions, the voltages connected to the in-phase input and the inverting input of the first comparator A and the second comparator B in the present application can be adjusted according to actual needs. For example, when the in-phase input of the first comparator A is connected to the reference voltage Vref and the inverting input of the first comparator A is connected to the input voltage Vuvp, when the reference voltage Vref is greater than the input voltage Vuvp, the first comparator A outputs a high level, and the first controller Q1 pulls down the power chip voltage Power-VCC when the first comparator A outputs a high level, and when the reference voltage Vref is less than the input voltage Vuvp, the first comparator A outputs a low level, and the first controller Q1 is turned on when the first comparator A outputs a low level, and controls the power chip voltage Power-VCC to be in a high level state. For example, when the non-inverting input terminal of the first comparator A is connected to the input voltage Vuvp and the inverting input terminal of the first comparator A is connected to the reference voltage Vref, when the reference voltage Vref is greater than the input voltage Vuvp, the first comparator A outputs a low level, and the first controller Q1 pulls down the power chip voltage Power-VCC when the first comparator A outputs a low level; when the reference voltage Vref is less than the input voltage Vuvp, the first comparator A outputs a high level, and the first controller Q1 controls the power chip voltage Power-VCC to be at a high level when the first comparator A outputs a high level. Similarly, when the in-phase input terminal of the second comparator B is connected to the reference voltage Vref, and the inverting input terminal of the second comparator B is connected to the input voltage Vuvp, when the reference voltage Vref is greater than the input voltage Vuvp, the second comparator B outputs a high level, and the second controller Q3 controls the circuit to be turned on when receiving the high level, and supplies power to the load to be powered. When the in-phase input terminal of the second comparator B is connected to the input voltage Vuvp, and the inverting input terminal of the second comparator B is connected to the reference voltage Vref, when the reference voltage Vref is greater than the input voltage Vuvp, the second comparator B outputs a low level, and the second controller Q3 controls the circuit to be turned on when receiving the low level. The first controller Q1 and the first comparator A output the same state level, and two cascaded NOT gates can be used as an inverter, and the inverter is the first controller Q1, or a non-inverting driver, a transmission gate, etc. can be used.

[0033] As a second embodiment of the present application, a protection device further includes: a rectifier filter circuit arranged between the input voltage Vuvp and the voltage detection circuit, the rectifier filter circuit at least includes a rectifier bridge BD and a first filter capacitor EC1, the input voltage Vuvp is connected to the input end of the rectifier bridge BD, and the first filter capacitor EC1 is connected in parallel to the output end of the rectifier bridge BD. When the input voltage Vuvp is mains power, the rectifier bridge BD converts the AC input mains power into a DC output, and the first filter capacitor EC1 is used to smooth the output voltage by storing charge and releasing the charge during the circuit transition period. When the DC voltage output by the rectifier bridge BD increases, the filter capacitor is charged and stores energy; when the output voltage drops, the filter capacitor releases the stored charge to replenish the energy in the circuit, thereby maintaining the stability of the output voltage.

[0034] The undervoltage detection circuit includes: a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a first protection capacitor C1 and a first comparator A, one end of the first voltage-dividing resistor R1 is connected to the live wire output end of the rectifier bridge BD, the other end of the first voltage-dividing resistor R1 is connected to one end of the second voltage-dividing resistor R2, the other end of the second voltage-dividing resistor R2 is connected to the zero line input end of the rectifier bridge BD, the first protection capacitor C1 is connected in parallel to the second voltage-dividing resistor R2, the non-inverting input end of the first comparator A is connected to the reference voltage Vref, and the inverting input end of the first comparator A is connected to the connection end of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2.

[0035] The first switch control circuit includes: a first controller Q1 and a first bias resistor R6, the base of the first controller Q1 is connected to the output end of the first comparator A, the collector of the first controller Q1 is connected to the power chip voltage Power-VCC end of the load to be powered, the emitter of the first controller Q1 is grounded, and the first bias resistor R6 is connected to the base and emitter of the first controller Q1.

[0036] The input voltage Vuvp is divided by the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2, and the first comparator A determines the comparison between the divided input voltage Vuvp and the reference voltage Vref. At this time, the reference voltage Vref is the lower limit reference voltage Vref, that is, when the divided input voltage Vuvp is less than the lower limit reference voltage Vref, the first comparator A controls the first controller Q1 to output a low level, pulls down the power chip voltage Power-VCC, and prevents the load to be powered from running in an undervoltage state. Here, when the divided input voltage Vuvp is less than the lower limit reference voltage Vref, the first comparator A outputs a high level, and the collector of the first controller Q1 outputs a low level. When the divided input voltage Vuvp is greater than the lower limit reference voltage Vref, the first comparator A outputs a high level, and the collector of the first controller Q1 outputs a high level, thereby controlling the power chip of the load to be powered to work only when the voltage is higher than the preset lower limit voltage, thereby avoiding the problem of unchanged power output power, reduced input voltage Vuvp, and increased input current, which leads to transformer saturation and power loop explosion.

[0037] The first bias resistor R6 can ensure that the transistor works stably in a required working area, prevent excessive current from damaging the transistor, and avoid the occurrence of self-oscillation.

[0038] The overvoltage detection circuit includes: a third voltage-dividing resistor R3, a fourth voltage-dividing resistor R4, a second protection capacitor C2 and a second comparator B, one end of the third voltage-dividing resistor R3 is connected to the live wire output end of the rectifier bridge BD, the other end of the third voltage-dividing resistor R3 is connected to one end of the fourth voltage-dividing resistor R4, the other end of the fourth voltage-dividing resistor R4 is connected to the neutral wire input end of the rectifier bridge BD, the first protection capacitor C1 is connected in parallel to the fourth voltage-dividing resistor R4, and the in-phase input end of the second comparator B is connected to the connection end of the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4.

[0039] The second switch control circuit includes: a second bias resistor R7, a second controller Q3, a third controller Q2, a third bias resistor R11, a first current limiting resistor R10 and a second filter capacitor EC2, the base of the third controller Q2 is connected to the output end of the second comparator B, the emitter of the third controller Q2 is grounded, the second bias resistor R7 is arranged between the emitter and the base of the third controller Q2, the collector of the third controller Q2 is connected to the gate of the second controller Q3 and one end of the first current limiting resistor R10, the other end of the first current limiting resistor R10 is connected to the positive power supply end VCC of the second comparator B, the source of the second controller Q3 is grounded, the drain of the second controller Q3 is connected to the negative electrode of the second filter capacitor EC2, the positive electrode of the second filter capacitor EC2 is connected to the live wire output end of the rectifier bridge BD, and the load to be powered is connected in parallel to the second filter capacitor EC2.

[0040] The input voltage Vuvp is divided by the third voltage-dividing resistor R3 and the fourth voltage-dividing resistor R4, and the first comparator A determines the comparison between the divided input voltage Vuvp and the reference voltage Vref. At this time, the reference voltage Vref is the upper limit reference voltage Vref, that is, when the input voltage Vuvp is less than the upper limit reference voltage Vref, the second comparator B outputs a low level, the third controller Q2 is turned off, and the gate of the second controller Q3 is powered by the loop from the positive power supply end of the second comparator B to the first current limiting resistor R10. At this time, the gate voltage Vg of the second controller Q3 is greater than the source voltage plus the rated threshold voltage of the MOS tube, and the second controller Q3 is turned on, so that the input current can pass through the second filter capacitor EC2 and the second controller Q3 and finally return to the ground end, so that the entire loop is closed and turned on, and when the input voltage Vuvp is greater than the upper limit reference voltage Vref, the second comparator B outputs a high level, the third controller Q2 is turned on, the gate voltage of the second controller Q3 is pulled down, and the second controller Q3 is not turned on, so that the input current cannot pass through the second controller Q3, the loop is disconnected, and the load to be powered cannot be powered through the second filter capacitor EC2.

[0041] In this embodiment, the on-off control of the circuit is realized by combining the second controller Q3 and the third controller Q2 without mechanical action, and the circuit can be cut off at the moment when the input voltage Vuvp is over-voltage, thereby ensuring that the circuit will not be affected.

[0042] As a third embodiment of the present application, a protection device also includes: a power supply protection circuit connected between the first switch control circuit and the load to be powered, the power supply protection circuit includes a pull-up resistor R8, a second current limiting resistor R9 and a rectifier diode ZD, one end of the pull-up resistor R8 is connected to the collector of the first controller Q1, the other end of the pull-up resistor R8 is connected to the load to be powered, one end of the second current limiting resistor R9 is connected to the live wire output end of the rectifier bridge BD, the other end of the second current limiting resistor R9 is connected to the collector of the first controller Q1, the positive electrode of the rectifier diode ZD is connected to the emitter of the first controller Q1, and the negative electrode of the rectifier diode ZD is connected to the collector of the first controller Q1.

[0043] In this embodiment, the pull-up resistor R8 ensures that when there is no other signal source, the input terminal of the power chip of the load to be powered is maintained in a stable high level state. The rectifier diode ZD ensures that when the collector of the transistor outputs a low level, no reverse current flows from the ground line or other low potential points through the transistor to the collector, thereby protecting the transistor from damage. The second current limiting resistor R9 limits the current flowing from the live wire into the collector of the first controller Q1. When the first controller Q1 is in the cut-off state, the second current limiting resistor R9 provides the necessary operating voltage for the collector of the first controller Q1.

[0044] In the present application, the load to be powered can be a device, a circuit, etc. The protection device can be separately arranged between the power supply of the load to be powered and the mains, or it can be assembled as a part of the power supply of the load to be powered. When the input voltage Vuvp is input to the protection device, the undervoltage state and the overvoltage state are judged at the same time. When the input voltage Vuvp is undervoltage, the voltage Power-VCC of the power supply chip of the load to be powered cannot reach the working voltage threshold. When the input voltage Vuvp is overvoltage, the power supply circuit of the control power supply is disconnected. In some cases, the second filter capacitor EC2 can also be the power supply of the device to be powered. Since the power supply cannot be powered, the load to be powered cannot operate in the overvoltage state.

[0045] As a fourth embodiment of the present application, a protection device also includes: a reference setting circuit connected to the reference voltage Vref input terminal of the voltage detection circuit, the reference setting circuit includes a protection resistor R5 and a voltage regulator, one end of the protection resistor R5 is connected to the power supply voltage terminal, the other end of the protection resistor R5 is connected to the cathode of the voltage regulator, the anode of the voltage regulator is grounded, and the reference end of the voltage regulator is connected to the reference voltage Vref input terminal.

[0046] In this embodiment, two reference setting circuits are provided, the reference end of the first reference setting circuit is connected to the non-inverting input end of the first comparator A, and the reference end of the second reference setting circuit is connected to the inverting input end of the second comparator B. Thus, the lower limit reference voltage Vref is provided for the first comparator A, and the upper limit reference voltage Vref is provided for the second comparator B, respectively.

[0047] Among them, the voltage regulator is TL431, which is a three-terminal adjustable shunt shunt regulator, and the voltage can be set and adjusted.

[0048] The specific implementation described above is a preferred implementation of a protective device of the utility model, and is not intended to limit the specific implementation scope of the utility model. The scope of the utility model includes but is not limited to this specific implementation. All equivalent changes made in accordance with the shape and structure of the utility model are within the protection scope of the utility model.

Claims

1. A protection device, arranged between an input voltage and a load to be powered, characterized in that: include: A voltage detection circuit whose input end is connected to an input voltage and a switch control circuit whose output end is connected to a load to be powered, the voltage detection circuit at least includes an undervoltage detection circuit and an overvoltage detection circuit, and the switch control circuit at least includes a first switch control circuit whose input end is connected to the undervoltage detection circuit and a second switch control circuit whose input end is connected to the overvoltage detection circuit; the output end of the first switch control circuit is connected to a power chip of the load to be powered, and the output end of the second switch control circuit is connected to a power supply circuit of the load to be powered.

2. A protection device according to claim 1, characterized in that: The undervoltage detection circuit includes at least a first comparator, the first switch control circuit includes at least a first controller, the non-inverting input terminal of the first comparator is connected to a reference voltage, the inverting input terminal of the first comparator is connected to an input voltage, the first controller is connected between the first comparator and a power chip of a load to be powered, and the first comparator outputs a high or low level to control the on and off of the first controller to control the power supply state of the load to be powered.

3. A protection device according to claim 1, characterized in that: The overvoltage detection circuit includes at least a second comparator, the second switch control circuit includes at least a second controller, the non-inverting input terminal of the second comparator is connected to the input voltage, the inverting input terminal of the second comparator is connected to the reference voltage, the second controller is connected between the input voltage and the power supply circuit of the load to be powered, and the second comparator outputs high and low levels to control the on and off of the second controller to control the power supply state of the load to be powered.

4. A protection device according to claim 1, characterized in that: It also includes: a rectifier filter circuit arranged between the input voltage and the voltage detection circuit, the rectifier filter circuit at least includes a rectifier bridge and a first filter capacitor, the input voltage is connected to the input end of the rectifier bridge, and the first filter capacitor is connected in parallel to the output end of the rectifier bridge.

5. A protection device as claimed in claim 4, characterized in that: The undervoltage detection circuit includes: a first voltage-dividing resistor, a second voltage-dividing resistor, a first protection capacitor and a first comparator, one end of the first voltage-dividing resistor is connected to the live wire output end of the rectifier bridge, the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is connected to the zero line input end of the rectifier bridge, the first protection capacitor is connected in parallel to the second voltage-dividing resistor, the non-inverting input end of the first comparator is connected to the reference voltage, and the inverting input end of the first comparator is connected to the connection end of the first voltage-dividing resistor and the second voltage-dividing resistor.

6. A protection device as claimed in claim 5, characterized in that: The first switch control circuit includes: a first controller and a first bias resistor, the base of the first controller is connected to the output end of the first comparator, the collector of the first controller is connected to the voltage end of the power chip of the load to be powered, the emitter of the first controller is grounded, and the first bias resistor is connected to the base and emitter of the first controller.

7. A protection device as claimed in claim 4, characterized in that: The overvoltage detection circuit includes: a third voltage-dividing resistor, a fourth voltage-dividing resistor, a second protection capacitor and a second comparator, one end of the third voltage-dividing resistor is connected to the live wire output end of the rectifier bridge, the other end of the third voltage-dividing resistor is connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is connected to the zero line input end of the rectifier bridge, the first protection capacitor is connected in parallel to the fourth voltage-dividing resistor, and the non-inverting input end of the second comparator is connected to the connection end of the third voltage-dividing resistor and the fourth voltage-dividing resistor.

8. A protection device according to claim 7, characterized in that: The second switch control circuit includes: a second bias resistor, a second controller, a third controller, a third bias resistor, a first current limiting resistor and a second filter capacitor, the base of the third controller is connected to the output end of the second comparator, the emitter of the third controller is grounded, the second bias resistor is arranged between the emitter and the base of the third controller, the collector of the third controller is connected to the gate of the second controller and one end of the first current limiting resistor, the other end of the first current limiting resistor is connected to the positive power supply end of the second comparator, the source of the second controller is grounded, the drain of the second controller is connected to the negative electrode of the second filter capacitor, the positive electrode of the second filter capacitor is connected to the live wire output end of the rectifier bridge, and the load to be powered is connected in parallel with the second filter capacitor.

9. A protection device according to claim 6, characterized in that: It also includes: a power supply protection circuit connected between the first switch control circuit and the load to be powered, the power supply protection circuit includes a pull-up resistor, a second current limiting resistor and a rectifier diode, one end of the pull-up resistor is connected to the collector of the first controller, the other end of the pull-up resistor is connected to the load to be powered, one end of the second current limiting resistor is connected to the live wire output end of the rectifier bridge, the other end of the second current limiting resistor is connected to the collector of the first controller, the positive electrode of the rectifier diode is connected to the emitter of the first controller, and the negative electrode of the rectifier diode is connected to the collector of the first controller.

10. A protection device according to claim 6, characterized in that: It also includes: a reference setting circuit connected to the reference voltage input terminal of the voltage detection circuit, the reference setting circuit includes a protection resistor and a voltage regulator, one end of the protection resistor is connected to the power supply voltage terminal, the other end of the protection resistor is connected to the cathode of the voltage regulator, the anode of the voltage regulator is grounded, and the reference end of the voltage regulator is connected to the reference voltage input terminal.

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