Input overvoltage protection circuit and protection method thereof

Abstract

The invention discloses an input overvoltage protection circuit and a protection method thereof, and relates to the technical field of overvoltage protection, the input end of an overvoltage detection module is coupled to the output voltage of a power adapter, and the overvoltage detection module is configured to output a trigger signal when the output voltage exceeds a preset threshold; the input end of the switch driving module is coupled to the output end of the overvoltage detection module, and the switch driving module is configured to be switched on in response to a trigger signal; the protection execution module comprises a relay, a coil of the relay is controlled by the output end of the switch driving module, and a normally open contact of the relay is connected to the two output ends of the power adapter in parallel. When the switch driving module is switched on, the coil of the relay is powered on, the normally open contact is driven to be closed, and the output of the power adapter is short-circuited. The technical problem that in the prior art, the input overvoltage point is a fixed value and cannot meet the requirements of various devices is solved, and the technical effects of adapting to the overvoltage protection requirements of various devices and preventing the devices from being damaged due to overvoltage are achieved.

Description

Technical Field

[0001] This invention relates to the field of overvoltage protection technology, specifically to an input overvoltage protection circuit and its protection method. Background Technology

[0002] Existing products require an adapter to convert AC power to the required DC power. If the adapter malfunctions, the output voltage may become excessively high, directly damaging the equipment. Therefore, overvoltage protection mechanisms are typically implemented at the device's input ports. However, current overvoltage protection circuits for device input ports use fixed overvoltage thresholds. Since different devices have varying tolerance ranges for input voltage and different overvoltage protection requirements, existing adapters are difficult to adapt to various device usage scenarios. Summary of the Invention

[0003] This application provides an input overvoltage protection circuit and its protection method, which addresses the technical problem that the input overvoltage point in the prior art is a fixed value and cannot meet the needs of various devices.

[0004] In view of the above problems, this application provides an input overvoltage protection circuit and its protection method.

[0005] A first aspect of this application provides an input overvoltage protection circuit, the circuit comprising: An overvoltage detection module, whose input is coupled to the output voltage of the power adapter, is configured to output a trigger signal when the output voltage exceeds a preset threshold. A switch drive module, whose input is coupled to the output of the overvoltage detection module, is configured to conduct in response to the trigger signal. A protection execution module includes a relay, the coil of which is controlled by the output of the switch drive module, and the normally open contact of which is connected in parallel across the output of the power adapter. When the switch drive module is turned on, the coil of the relay is energized, driving the normally open contact to close and short-circuit the output of the power adapter.

[0006] A second aspect of this application provides an input overvoltage protection method, the method comprising: The output voltage of the power adapter is sampled by a voltage divider resistor network to obtain a sampled voltage. The sampled voltage is compared with a reference voltage. When the sampled voltage exceeds the reference voltage, a trigger signal is output. In response to the trigger signal, the control switch drive module is switched from the off state to the on state. The on switch drive module supplies power to the coil of the relay, driving the normally open contact of the relay to close and short-circuit the output of the power adapter.

[0007] One or more technical solutions provided in this application have at least the following technical effects or advantages: The input terminal of the overvoltage detection module in this application is coupled to the output voltage of the power adapter and is configured to output a trigger signal when the output voltage exceeds a preset threshold. The input terminal of the switch drive module is coupled to the output terminal of the overvoltage detection module and is configured to conduct in response to the trigger signal. The protection execution module includes a relay, the coil of which is controlled by the output terminal of the switch drive module, and the normally open contact of the relay is connected in parallel across the output terminals of the power adapter. When the switch drive module is turned on, the coil of the relay is energized, driving the normally open contact to close and short-circuit the output of the power adapter. This invention solves the technical problem in the prior art where the input overvoltage point is a fixed value, which cannot meet the needs of various devices. By configuring a voltage divider resistor network with flexibly adjustable parameters, combined with a three-terminal programmable voltage regulator, a switch drive circuit, and a relay with a normally open contact, an overvoltage protection circuit is constructed. The resistance value of the voltage divider resistor is determined according to the target overvoltage protection threshold of the protected device, achieving the technical effect of adapting to the overvoltage protection needs of various devices and avoiding equipment damage due to overvoltage. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 A schematic diagram of an input overvoltage protection circuit structure provided in an embodiment of this application; Figure 2 A schematic diagram of the working principle of an input overvoltage protection circuit provided in an embodiment of this application; Figure 3 A schematic diagram of an input overvoltage protection circuit that operates normally without input overvoltage, provided in an embodiment of this application; Figure 4 This application provides a schematic diagram of an input overvoltage protection circuit in the event of an input overvoltage abnormality. Figure 5 This is a schematic flowchart of an input overvoltage protection method provided in an embodiment of this application.

[0010] Explanation of reference numerals in the attached diagram: Overvoltage detection module 11, switch drive module 12, protection execution module 13. Detailed Implementation

[0011] This application provides an input overvoltage protection circuit and method, addressing the technical problem that existing technologies use fixed input overvoltage points, which cannot meet the needs of various devices. The overvoltage protection circuit is constructed by configuring a voltage divider resistor network with flexibly adjustable parameters, combined with a three-terminal programmable voltage regulator, a switch drive circuit, and a relay with normally open contacts. The resistance value of the voltage divider resistor is determined according to the target overvoltage protection threshold of the protected device, achieving the technical effect of adapting to the overvoltage protection needs of various devices and preventing equipment damage due to overvoltage.

[0012] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0013] It should be noted that any variation of the terms "comprising" and "having" is intended to cover non-exclusive inclusion, for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or modules that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0014] Example 1, as Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, this application provides an input overvoltage protection circuit, wherein, Figure 2 The circuit architecture is presented, covering the connection relationships of core components such as voltage divider resistor networks, three-terminal programmable voltage regulators, switch drive circuits, and relays, and the signal transmission paths and electrical connection methods between each component are clearly defined. Figure 3 When the power adapter output voltage is within the normal range, the sampling voltage output by the voltage divider resistor network is lower than the reference voltage. The switch drive circuit remains off, the relay coil has no supply current, the normally open contact remains open, and the power adapter normally supplies power to the subsequent equipment. This visually demonstrates the circuit's operating status when there is no overvoltage abnormality. Figure 4 When the power adapter output voltage exceeds the target overvoltage protection threshold, the sampled voltage output by the voltage divider resistor network is higher than the reference voltage. After the trigger signal is output, the switch drive circuit is turned on, the relay coil is energized, and the normally open contact is closed, short-circuiting the power adapter output and achieving overvoltage protection. This demonstrates the circuit's protection action execution process under abnormal operating conditions. The circuit includes: An overvoltage detection module 11 is configured to output a trigger signal when the output voltage exceeds a preset threshold. The input terminal of the overvoltage detection module 11 is coupled to the output voltage of the power adapter.

[0015] In this embodiment, the input terminal of the overvoltage detection module 11 is coupled to the output voltage of the power adapter. This connection method ensures that the overvoltage detection module 11 obtains the true value of the power adapter's output voltage in real time and accurately.

[0016] The overvoltage detection module 11 has voltage monitoring and comparison functions. During operation, the overvoltage detection module 11 continuously acquires the output voltage signal of the coupled power adapter, and simultaneously compares the acquired real-time voltage signal with a preset threshold value in real time without interruption. The preset threshold value is a voltage critical value determined based on the voltage tolerance limit of the protected equipment and specific usage requirements.

[0017] When the overvoltage detection module 11 detects that the output voltage of the power adapter has increased and exceeded the preset threshold, it indicates that the protected device is at risk of overvoltage damage. At this time, the overvoltage detection module 11 will immediately activate the signal output mechanism to generate and output a trigger signal.

[0018] Furthermore, in the circuit provided in the application embodiment, the overvoltage detection module 11 further includes: A three-terminal programmable voltage regulator U1, a first voltage divider resistor R1, and a second voltage divider resistor R2; wherein, the first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series to the output voltage of the power adapter. Between the voltage regulator and ground, the connection point is coupled to the reference terminal of the three-terminal programmable voltage regulator U1; the anode of the three-terminal programmable voltage regulator U1 is grounded, and the cathode serves as the output terminal of the overvoltage detection module 11, outputting the trigger signal.

[0019] In this embodiment, the overvoltage detection module 11 includes a three-terminal programmable voltage regulator U1, a first voltage divider resistor R1, and a second voltage divider resistor R2. The three-terminal programmable voltage regulator U1 is a component with a reference voltage comparison function, and the first voltage divider resistor R1 and the second voltage divider resistor R2 are key components constituting the voltage divider network. The three components work together to realize the overvoltage detection of the power adapter output voltage.

[0020] The first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series to the output voltage of the power adapter. The connection point between the voltage divider and ground forms a voltage divider node. This voltage divider node is coupled to the reference terminal of the three-terminal programmable voltage regulator U1. The anode of the three-terminal programmable voltage regulator U1 is directly grounded, while the cathode is explicitly used as the output terminal of the overvoltage detection module 11, specifically for outputting a trigger signal.

[0021] The three-terminal programmable voltage regulator U1 has a built-in fixed reference voltage of 2.5V, which serves as a reference standard for determining whether the voltage is overvoltage. The voltage divider network formed by the first voltage divider resistor R1 and the second voltage divider resistor R2 is used to divide the output voltage of the power adapter... Voltage is divided according to the resistance ratio of the two components.

[0022] When the power adapter output voltage When applied across the series voltage divider network, a voltage divider node will form a voltage divider network with the voltage divider node. A voltage divider is formed in a fixed ratio. The magnitude of this voltage divider is directly determined by the resistance ratio of R1 and R2. By adjusting the resistance ratio of the two, the value of the voltage divider can be flexibly changed, thereby realizing the personalized setting of the overvoltage judgment standard to adapt to the overvoltage protection needs of different devices.

[0023] When the power adapter output voltage When within the normal range, the voltage at the voltage divider node is lower than the built-in reference voltage of the three-terminal programmable voltage regulator U1. At this time, the cathode of the three-terminal programmable voltage regulator U1 remains at a high level, and the overvoltage detection module 11 does not output a trigger signal, ensuring normal operation of the equipment.

[0024] With the power adapter output voltage As the voltage increases, the voltage at the voltage divider node will rise synchronously. When the overvoltage detection module 11 detects that the voltage at the voltage divider node exceeds the built-in reference voltage of the three-terminal programmable voltage regulator U1, it indicates that the voltage has reached the overvoltage threshold. The cathode level state of the three-terminal programmable voltage regulator U1 will flip from high level to low level, and the flipped level signal is the trigger signal, which is output through its cathode.

[0025] The input terminal of the switch drive module 12 is coupled to the output terminal of the overvoltage detection module 11 and is configured to be turned on in response to the trigger signal.

[0026] In this embodiment, the input terminal of the switch driving module 12 is coupled to the output terminal of the overvoltage detection module 11. This connection method ensures that the signal output by the overvoltage detection module 11 is accurately transmitted to the switch driving module 12, thus ensuring the stability of signal interaction between the modules.

[0027] The operating state of the switch drive module 12 is determined by the state of the input signal, and it is configured to perform a conduction action only when a trigger signal is received. When no trigger signal is received from the overvoltage detection module 11, the switch drive module 12 remains in the off state, and no signal is generated to drive subsequent components, thus not affecting the normal operation of the equipment.

[0028] When the overvoltage detection module 11 detects that the power adapter output voltage exceeds a preset threshold and outputs a trigger signal, the trigger signal is transmitted to the input terminal of the switch driver module 12 through a coupling relationship. After receiving the trigger signal, the switch driver module 12 starts its internal conduction mechanism according to the preset working logic, completing the transition from the off state to the on state.

[0029] Furthermore, in the circuit provided in the application embodiment, the switch driving module 12 further includes: An NPN transistor Q2 and an N-channel MOSFET Q1 are used. The base of the NPN transistor Q2 is coupled to the cathode of the three-terminal programmable voltage regulator U1 through a third resistor R3, the emitter is grounded, and the collector is coupled to the gate of the N-channel MOSFET Q1 through a fourth resistor R4. The source of the N-channel MOSFET Q1 is grounded, and the drain is coupled to the first terminal of the coil of the relay K1.

[0030] In this embodiment, the switch drive module 12 includes an NPN transistor Q2 and an N-channel MOSFET Q1, and is also equipped with a third resistor R3 and a fourth resistor R4. The components are connected by specific electrical connections to form a complete drive link.

[0031] The base of the NPN transistor Q2 is coupled to the cathode of the three-terminal programmable voltage regulator U1 through the third resistor R3. The third resistor R3 limits the base current and protects the NPN transistor Q2. The emitter of the NPN transistor Q2 is directly grounded, while the collector is coupled to the gate of the N-channel MOSFET Q1 through the fourth resistor R4. The fourth resistor R4 is used to stabilize the gate voltage of the N-channel MOSFET Q1 and prevent voltage fluctuations from affecting the device's operating state.

[0032] The source of the N-channel MOSFET Q1 is grounded, and its drain is coupled to the first terminal of the coil of relay K1, providing a power supply path for the coil of relay K1.

[0033] When the three-terminal programmable voltage regulator U1 does not output a trigger signal, its cathode remains at a high level, the base of the NPN transistor Q2 has insufficient drive current and is in the cutoff state; at this time, the gate of the N-channel MOSFET Q1 has no voltage signal required for conduction and also remains in the cutoff state, and no current flows through the coil of the relay K1.

[0034] When the three-terminal programmable voltage regulator U1 outputs a trigger signal (cathode level pulled low), the signal is transmitted to the base of the NPN transistor Q2 through the third resistor R3, causing the NPN transistor Q2 to obtain a forward bias current and conduct. After the NPN transistor Q2 conducts, its collector potential changes, and the driving voltage is transmitted to the gate of the N-channel MOSFET Q1 through the fourth resistor R4, so that the N-channel MOSFET Q1 meets the conduction condition and conducts. After the N-channel MOSFET Q1 conducts, the coil of the relay K1 obtains a power supply path through the drain.

[0035] Furthermore, the circuit provided in the application embodiments also includes: The second terminal of the coil of the relay K1 is coupled to the output voltage of the power adapter. The voltage division ratio of the first voltage divider resistor R1 and the second voltage divider resistor R2, together with the internal reference voltage of the three-terminal programmable voltage regulator U1, sets a preset threshold; when the output voltage... When the preset threshold is exceeded, the cathode level of the three-terminal programmable voltage regulator U1 is pulled low, causing the NPN transistor Q2 to conduct, which in turn drives the N-channel MOSFET Q1 to conduct, thereby energizing the coil of the relay K1.

[0036] In this embodiment, the second terminal of the coil of relay K1 is connected to the output voltage of the power adapter. This coupling provides a power source for the coil of relay K1, ensuring that the coil receives the voltage required to energize when conditions are met.

[0037] The first voltage divider resistor R1 and the second voltage divider resistor R2 are connected in series to form a voltage divider network. The voltage division ratio between the two resistors can change the output voltage of the power adapter. The voltage division at the voltage divider node, and the internal reference voltage of the three-terminal programmable regulator U1 is a fixed voltage reference standard. The voltage division ratio and the internal reference voltage work together to determine the preset threshold for judging whether the power adapter output voltage is overvoltage.

[0038] When the power adapter output voltage When within the normal range, the voltage obtained after voltage division by the first voltage divider resistor R1 and the second voltage divider resistor R2 is lower than the internal reference voltage of the three-terminal programmable voltage regulator U1. At this time, the cathode of the three-terminal programmable voltage regulator U1 remains at a high level, the NPN transistor Q2 is in the cutoff state because there is no sufficient driving current at the base, the N-channel MOSFET Q1 is also kept in the cutoff state, and no current flows through the coil of the relay K1, which is always in the de-energized state.

[0039] When the power adapter output voltage When the voltage rises and exceeds a preset threshold, the voltage divided by the first voltage divider resistor R1 and the second voltage divider resistor R2 rises synchronously and exceeds the internal reference voltage of the three-terminal programmable voltage regulator U1. At this time, the cathode level of the three-terminal programmable voltage regulator U1 is pulled low. This pulled-low voltage signal is transmitted to the base of the NPN transistor Q2, causing the NPN transistor Q2 to obtain a forward bias current and turn on. After the NPN transistor Q2 turns on, its collector potential changes, and the driving voltage is transmitted to the gate of the N-channel MOSFET Q1 through the fourth resistor R4, so that the N-channel MOSFET Q1 meets the conduction condition and completes conduction.

[0040] After the N-channel MOSFET Q1 is turned on, the coil of relay K1 is connected to the output voltage of the power adapter through its drain. A complete power supply circuit is formed, and current flows through the coil, energizing the coil of relay K1.

[0041] Furthermore, the circuit provided in the application embodiments also includes: Output voltage Under normal conditions, the first and third pins of the three-terminal programmable voltage regulator U1 are not conducting, resulting in infinite impedance. Transistor Q2 is not conducting, N-channel MOSFET Q1 is not conducting, and the relay contacts are not engaging, indicating that the device is operating normally.

[0042] In this embodiment of the application, when the output voltage of the power adapter When within the normal range, the voltage divider network composed of the first voltage divider resistor R1 and the second voltage divider resistor R2... After voltage division, the resulting voltage is lower than the internal reference voltage of the three-terminal programmable voltage regulator U1. At this time, the first and third pins of the three-terminal programmable voltage regulator U1 remain non-conductive, exhibiting infinite impedance between the two pins. No current flows through the path formed by these two pins, and the cathode of the three-terminal programmable voltage regulator U1 maintains a high-level output.

[0043] The base of NPN transistor Q2 is coupled to the cathode of three-terminal programmable voltage regulator U1 through the third resistor R3. Since the cathode is at a high level, the base of NPN transistor Q2 cannot obtain sufficient forward bias current, so NPN transistor Q2 remains in a non-conducting state.

[0044] The gate of the N-channel MOSFET Q1 is coupled to the collector of the NPN transistor Q2 through the fourth resistor R4. Since the NPN transistor Q2 is not conducting, its collector cannot provide the gate drive voltage required for the N-channel MOSFET Q1 to conduct, so the N-channel MOSFET Q1 is also in a non-conducting state.

[0045] The first terminal of the coil of relay K1 is coupled to the drain of N-channel MOSFET Q1, and the second terminal is coupled to the output voltage of the power adapter. Because the N-channel MOSFET Q1 is not conducting, the coil of relay K1 cannot form a complete power supply circuit, and no current flows through the coil, causing the contacts of relay K1 to remain in an unclosed state.

[0046] The normally open contact of relay K1 is connected in parallel across the output terminals of the power adapter. When the contact is not engaged, the output voltage of the power adapter is... It can be transmitted normally to the input terminal of the protected device, so that the protected device can obtain a stable operating voltage and thus achieve normal operation.

[0047] Furthermore, the circuit provided in the application embodiments also includes: The closure of the normally open contact of the relay is the only operating component for input voltage short-circuit protection.

[0048] In this embodiment, the normally open contact of the relay is connected in parallel across the output terminals of the power adapter. This normally open contact is the sole operating component for input voltage short-circuit protection. Throughout the entire input voltage short-circuit protection process, the overvoltage detection module 11 only monitors and compares the output voltage of the power adapter. When the output voltage exceeds a preset threshold, it outputs a trigger signal. The switch drive module 12 only receives and converts the trigger signal, energizing the relay coil. Neither of these modules directly participates in the execution of the short-circuit protection. After the relay coil is energized, it generates electromagnetic attraction, driving its normally open contact from an open state to a closed state. This closing action directly establishes electrical connection between the positive and negative terminals of the power adapter output, thereby achieving input voltage short-circuit protection. The entire short-circuit protection function is completed solely through the closing action of the relay's normally open contact.

[0049] Furthermore, the circuit provided in the application embodiments also includes: The NPN transistor Q2 and N-channel MOSFET Q1 in the switch drive module 12 are replaced by a switch.

[0050] In this embodiment, the NPN transistor Q2 and N-channel MOSFET Q1 in the switch drive module 12 are replaced by a switch. This switch takes over the signal transmission and on / off control functions of the original NPN transistor Q2 and N-channel MOSFET Q1 in the switch drive module 12, and its connection relationship in the circuit is consistent with the drive link formed by the original NPN transistor Q2 and N-channel MOSFET Q1. The input terminal of the switch is coupled to the cathode of the three-terminal programmable voltage regulator U1 to receive the level signal output by the three-terminal programmable voltage regulator U1. The output terminal of the switch is coupled to the first terminal of the coil of relay K1, thereby realizing the on / off control of the power supply circuit of relay K1 coil through the on / off state change of the switch itself.

[0051] The protection execution module 13 includes a relay, the coil of which is controlled by the output terminal of the switch drive module 12, and the normally open contact of the relay is connected in parallel across the output terminals of the power adapter. When the switch drive module 12 is turned on, the coil of the relay is energized, driving the normally open contact to close and short-circuit the output of the power adapter.

[0052] In this embodiment, the protection execution module 13 includes a relay. The coil of the relay is coupled to the output terminal of the switch drive module 12. Its working state is completely controlled by the level state of the output terminal of the switch drive module 12. The normally open contact of the relay is connected in parallel to the output terminals of the power adapter. The normally open contact is a contact component in the relay that is normally kept in an open state and only closes mechanically when the relay coil is energized.

[0053] When the switch drive module 12 receives the trigger signal output by the overvoltage detection module 11 and completes the conduction action, the relay coil forms a complete power supply circuit through the switch drive module 12. Current flows through the coil to energize it. The energized coil generates an electromagnetic attraction force, which drives the normally open contact of the relay to change from the normally open state to the closed state.

[0054] When the normally open contact of the relay closes, the output terminals of the power adapter connected in parallel are electrically connected, directly short-circuiting the output of the power adapter. This cuts off the abnormal power supply from the power adapter to subsequent equipment, thus achieving overvoltage and short-circuit protection for the power adapter and subsequent protected equipment.

[0055] In summary, the embodiments of this application have at least the following technical effects: The input terminal of the overvoltage detection module in this application is coupled to the output voltage of the power adapter and is configured to output a trigger signal when the output voltage exceeds a preset threshold. The input terminal of the switch drive module is coupled to the output terminal of the overvoltage detection module and is configured to conduct in response to the trigger signal. The protection execution module includes a relay, the coil of which is controlled by the output terminal of the switch drive module, and the normally open contact of the relay is connected in parallel across the output terminals of the power adapter. When the switch drive module is turned on, the coil of the relay is energized, driving the normally open contact to close and short-circuit the output of the power adapter. This invention solves the technical problem in the prior art where the input overvoltage point is a fixed value, which cannot meet the needs of various devices. By configuring a voltage divider resistor network with flexibly adjustable parameters, combined with a three-terminal programmable voltage regulator, a switch drive circuit, and a relay with normally open contacts, an overvoltage protection circuit is constructed. The resistance value of the voltage divider resistor is determined according to the target overvoltage protection threshold of the protected device to achieve the technical effect of adapting to the overvoltage protection needs of various devices and avoiding equipment damage due to overvoltage.

[0056] Example 2, based on the same inventive concept as the input overvoltage protection circuit in the aforementioned examples, such as... Figure 5 As shown, this application provides an input overvoltage protection method. The method and circuit embodiments of this application are based on the same inventive concept. The method includes: The output voltage of the power adapter is sampled by dividing the voltage using a voltage divider resistor network to obtain the sampled voltage.

[0057] In this embodiment, the voltage divider resistor network is composed of a first voltage divider resistor R1 and a second voltage divider resistor R2 connected in series, and the entire voltage divider resistor network is connected to the output voltage of the power adapter. Between the ground and the first voltage divider resistor R1 and the second voltage divider resistor R2, the connection point forms a voltage divider node, which serves as a voltage sampling point for obtaining the sampled voltage.

[0058] Output voltage of power adapter When applied across the first voltage divider resistor R1 and the second voltage divider resistor R2 connected in series, according to the voltage divider principle of series circuits, the output voltage... The voltage is distributed according to the resistance ratio of the first voltage divider resistor R1 and the second voltage divider resistor R2, forming a voltage at the voltage divider node that corresponds to the output voltage. A voltage value that is proportional to a fixed ratio is called the sampling voltage.

[0059] The sampled voltage is compared with a reference voltage.

[0060] In this embodiment, the sampled voltage at the voltage divider node is coupled to the reference terminal of the three-terminal programmable voltage regulator U1. The three-terminal programmable voltage regulator U1 has a built-in fixed reference voltage, and the three-terminal programmable voltage regulator U1 performs real-time comparison between the sampled voltage and the reference voltage through its internal circuit.

[0061] When the sampled voltage exceeds the reference voltage, a trigger signal is output.

[0062] In this embodiment, when the sampling voltage exceeds the reference voltage, the cathode level of the three-terminal programmable voltage regulator U1 changes from high level to low level, and this level signal is the trigger signal and is output to the outside.

[0063] In response to the trigger signal, the control switch drive module 12 is switched from the off state to the on state. The on switch drive module 12 supplies power to the coil of the relay, driving the normally open contact of the relay to close and short-circuiting the output of the power adapter.

[0064] In this embodiment, the input terminal of the switch driving module 12 receives and responds to a trigger signal, performing a transition operation from an off state to an on state. After the switch driving module 12 is turned on, the coil of the relay K1 is connected to the output voltage of the power adapter through the switch driving module 12. To form a complete power supply circuit, the output voltage of the power adapter A working current is supplied to the coil of relay K1, energizing it. The energized coil generates an electromagnetic force, which drives the normally open contacts connected in parallel across the power adapter output terminals to close. Once the normally open contacts of relay K1 close, the positive and negative terminals of the power adapter output are electrically connected, directly short-circuiting the power adapter output and completing the overvoltage / short-circuit protection action.

[0065] Furthermore, in the method provided in the application embodiments, before sampling the output voltage of the power adapter through a voltage divider resistor network, the method further includes: Obtain the target overvoltage protection threshold of the protected equipment; based on the target overvoltage protection threshold, the reference voltage, and the first voltage divider resistor R1, use the formula: The resistance value of the second voltage divider resistor R2 is calculated, where, For reference voltage, The target overvoltage protection threshold is set; the voltage divider resistor network of the input overvoltage protection circuit is configured according to the first voltage divider resistor R1 and the second voltage divider resistor R2.

[0066] Furthermore, the method provided in the application embodiments also includes: The reference voltage The voltage is 2.5V, and the first voltage divider resistor R1 is set to 100k ohms.

[0067] In this embodiment, the target overvoltage protection threshold of the protected device is first obtained. The target overvoltage protection threshold is the upper limit of the power adapter output voltage set to ensure the safe operation of the protected device.

[0068] Based on the obtained target overvoltage protection threshold and the built-in reference voltage of the three-terminal programmable voltage regulator, and combined with the voltage divider principle of series circuits, the resistance ratio of the first voltage divider resistor R1 and the second voltage divider resistor R2 in the voltage divider resistor network is derived and determined. The target overvoltage protection threshold, the reference voltage, and the voltage divider resistors satisfy the following relationship: In the formula This is the fixed reference voltage inside the three-terminal programmable voltage regulator, specifically set to 2.5V. To determine the target overvoltage protection threshold, the resistance value of the first voltage divider resistor R1 is set to 100k ohms. The resistance value of the second voltage divider resistor R2 is then calculated using this formula.

[0069] Subsequently, the first voltage divider resistor R1 and the second voltage divider resistor R2, whose resistance values ​​have been determined, are connected in series and coupled together between the power adapter output voltage and ground. The connection point of the first voltage divider resistor R1 and the second voltage divider resistor R2 serves as a voltage divider node and is coupled to the reference terminal of the three-terminal programmable voltage regulator, thereby completing the voltage divider resistor network configuration of the input overvoltage protection circuit.

[0070] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An input overvoltage protection circuit, characterized by, The input overvoltage protection circuit is connected between an output end of a power adapter and an input end of a protected device, and comprises: an overvoltage detection module, an input end of the overvoltage detection module being coupled to an output voltage of the power adapter and being configured to output a trigger signal when the output voltage exceeds a preset threshold value; a switch driving module, an input end of the switch driving module being coupled to an output end of the overvoltage detection module and being configured to be turned on in response to the trigger signal; a protection execution module, the protection execution module comprising a relay, a coil of the relay being controlled by an output end of the switch driving module, and a normally open contact of the relay being connected in parallel across the output of the power adapter; wherein, when the switch driving module is turned on, the coil of the relay is energized to drive the normally open contact to be closed, thereby short-circuiting the output of the power adapter.

2. The input overvoltage protection circuit of claim 1, wherein The overvoltage detection module comprises a three-terminal programmable voltage regulator (U1), a first voltage dividing resistor (R1) and a second voltage dividing resistor (R2). Wherein, the first voltage dividing resistor (R1) and the second voltage dividing resistor (R2) are connected in series between the output voltage of the power adapter ) and the ground, and the connecting point is coupled to the reference end of the three-terminal programmable voltage regulator (U1). The anode of the three-terminal programmable voltage regulator (U1) is grounded, and the cathode thereof serves as an output end of the overvoltage detection module and outputs the trigger signal.

3. The input overvoltage protection circuit of claim 2, wherein, The switch driving module comprises an NPN-type triode (Q2) and an N-channel MOS tube (Q1). The base of the NPN-type triode (Q2) is coupled to the cathode of the three-terminal programmable voltage regulator (U1) through a third resistor (R3), the emitter thereof is grounded, and the collector thereof is coupled to the gate of the N-channel MOS tube (Q1) through a fourth resistor (R4). The source of the N-channel MOS tube (Q1) is grounded, and the drain thereof is coupled to a first end of the coil of the relay (K1).

4. The input overvoltage protection circuit of claim 3, wherein, The second end of the coil of the relay (K1) is coupled to the output voltage of the power adapter ; The voltage dividing ratio of the first voltage dividing resistor (R1) and the second voltage dividing resistor (R2) and the internal reference voltage of the three-terminal programmable voltage regulator (U1) together set the preset threshold value. When the output voltage ( When the threshold is exceeded, the cathode level of the three-terminal programmable voltage regulator (U1) is pulled low, which turns on the NPN transistor (Q2), drives the N-channel MOSFET (Q1) to turn on, and energizes the coil of the relay (K1).

5. The input overvoltage protection circuit of claim 4, wherein, Output voltage (Vout) When normal, the first pin and the third pin of the three-terminal programmable voltage regulator (U1) are not conductive, the impedance is infinite, the transistor (Q2) is not conductive, the N-channel MOS transistor (Q1) is not conductive, and the relay contact is not attracted, so the device works normally.

6. The input overvoltage protection circuit of claim 1, wherein, The closure of the normally open contact of the relay is the only moving component of the input voltage short-circuit protection.

7. The input overvoltage protection circuit of claim 3, wherein, The NPN-type triode (Q2) and the N-channel MOS tube (Q1) in the switch driving module are replaced by switches.

8. An input overvoltage protection method, characterized by, The input overvoltage protection method is applied to the input overvoltage protection circuit of any one of claims 1-7, and comprises: sampling and dividing the output voltage of the power adapter through a voltage dividing resistor network to obtain a sampling voltage; comparing the sampling voltage with a reference voltage; outputting a trigger signal when the sampling voltage exceeds the reference voltage; in response to the trigger signal, controlling a switch driving module to switch from an off state to an on state, supplying power to the coil of the relay through the switch driving module in the on state, driving the normally open contact of the relay to be closed, and short-circuiting the output of the power adapter.

9. The input overvoltage protection method of claim 8, wherein, Before sampling and dividing the output voltage of the power adapter through the voltage dividing resistor network, the method comprises: obtaining a target overvoltage protection threshold value of a protected device; According to the target overvoltage protection threshold, the reference voltage and the first voltage dividing resistor (R1), the resistance of the second voltage dividing resistor (R2) is calculated by the formula: , wherein, is the reference voltage, is the target overvoltage protection threshold. configuring a voltage dividing resistor network of the input overvoltage protection circuit according to the first voltage dividing resistor (R1) and the second voltage dividing resistor (R2).

10. The input overvoltage protection method of claim 9, wherein, The reference voltage The first voltage divider resistor (R1) is set to 100 kOhms.

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