Power supply protection circuit and power supply protection system

Abstract

The application discloses a power protection circuit and a power protection system, the power protection circuit comprising a primary protection circuit and a secondary protection circuit; the primary protection circuit comprising a bidirectional transient voltage suppression diode connected in parallel with a power input end; the secondary protection circuit comprising a voltage comparator and an electronic switch; a positive input end of the voltage comparator being connected with a positive electrode of the power input end and a common end of the bidirectional transient voltage suppression diode, and a negative input end being connected with a reference voltage source of a preset voltage threshold; a control end of the electronic switch being connected with an output end of the voltage comparator, and a controlled path being connected in series between the power input end and a protected device, for cutting off the connection between the power and the protected device in response to an abnormal voltage signal output by the voltage comparator. The primary protection circuit focuses on transient overvoltage suppression, and the secondary protection circuit is responsible for the monitoring and rapid cutting off of continuous overvoltage, the two being complementary in function and capable of realizing reliable protection of the protected device.

Description

Technical Field

[0001] This application generally relates to the technical field of circuit safety protection. More specifically, this application relates to a power protection circuit and a power protection system. Background Technology

[0002] Hot-swapping is a common operation and maintenance scenario for POS (Point of Sale) terminals. Hot-swapping refers to directly plugging or unplugging internal modular components while the POS machine is powered on. For example, plugging or unplugging the card reader module or communication module without first shutting down the power (whether it's the POS machine's built-in power supply or an external power supply). This operation is frequently used during routine maintenance or feature expansion to minimize POS machine downtime and ensure continuous transaction processing.

[0003] In practical applications, hot-swapping operations, such as connecting or disconnecting external functional modules, expose the POS machine's power circuit to significant transient stress changes. When a module is inserted, the interface capacitor rapidly connects to the internal power circuit, generating a large instantaneous charging current (surge current). This current induces high-frequency oscillations in the parasitic inductance of the path, potentially triggering transient overvoltage spikes. Conversely, when a module is removed, the circuit abruptly disconnects, and the magnetic and electrical energy stored in the circuit creates a reverse electromotive force, resulting in a high-amplitude transient voltage backflow. If these transient overvoltage events occur frequently or violently, they may further cause transient imbalances in the power regulation loop, resulting in a continuous deviation of the power output from its rated value for milliseconds to seconds, thus evolving into a sustained overvoltage state, posing a serious threat to the POS machine's core chip, which is always connected to the power bus.

[0004] These abnormal power circuit conditions caused by hot-swapping operations are the core reason for damage to POS machine module interfaces, data loss, and even burnout of the main control chip, which directly affects the safety and reliability of the equipment.

[0005] In view of this, there is an urgent need to provide a power protection circuit and a power protection system for POS machines in order to protect the equipment. Utility Model Content

[0006] In order to at least solve one or more of the technical problems mentioned above, this application proposes a power protection circuit and a power protection system in several aspects.

[0007] In a first aspect, this application provides a power supply protection circuit, comprising: a primary protection circuit and a secondary protection circuit; wherein the primary protection circuit includes a bidirectional transient voltage suppressor diode connected in parallel with the power input terminal to clamp transient overvoltages of the power supply within a safe range; the secondary protection circuit includes a voltage comparator and an electronic switch; wherein the non-inverting input terminal of the voltage comparator is connected to the common terminal of the positive terminal of the power input terminal and the bidirectional transient voltage suppressor diode, and the inverting input terminal is connected to a reference voltage source with a preset voltage threshold, for real-time acquisition of the power input voltage at the power input terminal and comparison with the preset voltage threshold, and outputting a voltage abnormality signal when the power input voltage exceeds the preset voltage threshold; the control terminal of the electronic switch is connected to the output terminal of the voltage comparator, and a controlled path is connected in series between the power input terminal and the protected device, for responding to the voltage abnormality signal output by the voltage comparator to switch the controlled path from an on state to an off state, thereby disconnecting the connection between the power supply and the protected device.

[0008] In some embodiments, the electronic switch includes a PMOS transistor; wherein the gate of the PMOS transistor is connected to the output terminal of the voltage comparator; the source of the PMOS transistor is connected to the power input terminal, and the drain is connected to the protected device, forming a controlled path connected in series in the power supply circuit of the power supply and the protected device.

[0009] In some embodiments, the primary protection circuit further includes an inductor connected in series at the front end of the power input terminal to filter out high-frequency noise introduced into the power input voltage.

[0010] In some embodiments, the inductor includes a multilayer chip inductor.

[0011] In some embodiments, the secondary protection circuit further includes a sampling resistor, a current detection amplifier, a controller, and a first logic OR gate circuit; wherein, the sampling resistor is connected in series in the main circuit between the positive terminal of the power input and the protected device; the input terminal of the current detection amplifier is connected in parallel with the sampling resistor to collect the voltage difference across the sampling resistor; The input terminal of the controller is connected to the output terminal of the current sensing amplifier. It is used to calculate the power input current at the power input terminal based on the voltage difference output by the current sensing amplifier, and compare the power input current with a preset overcurrent protection threshold. When the power input current exceeds the preset overcurrent protection threshold, it outputs a current abnormality signal. The output terminal of the controller and the voltage comparator are connected to the control terminal of the electronic switch through a first logic OR gate circuit. When the electronic switch receives the current abnormality signal output by the controller and / or receives the voltage abnormality signal output by the voltage comparator, it switches the controlled path from the on state to the off state, thereby cutting off the connection between the power supply and the protected device.

[0012] In some embodiments, the electronic switch includes a PMOS transistor; wherein the gate of the PMOS transistor is connected to the output of the first logic OR gate circuit; the source of the PMOS transistor is connected to the low potential end of the sampling resistor, and the drain is connected to the positive terminal of the protected device, thereby forming a series controlled path between the power supply and the protected device.

[0013] In some embodiments, a three-level protection circuit is further included; wherein the three-level protection circuit includes a fuse connected in series between the output terminal of the electronic switch and the protected device, for disconnecting the connection between the power supply and the protected device when the electronic switch fails and an overcurrent occurs.

[0014] In some embodiments, the fuse is a resettable fuse, used to disconnect the connection between the power supply and the protected device when the electronic switch fails and there is an overcurrent, and to automatically reconnect after normal operation is restored, thereby restoring the connection between the power supply and the protected device.

[0015] In some embodiments, an alert circuit is further included, which includes a trigger and / or a current-limiting resistor and an LED; wherein the input of the trigger is connected to the output of a first logic OR gate circuit, and the output is connected to the main control device and the anode of the LED light through the current-limiting resistor; when the first logic OR gate circuit outputs an abnormal signal, the trigger enters a latching state and outputs a high level, sending an alarm signal to the main control device and lighting up the LED light.

[0016] In a second aspect, this application also provides a power protection system, including a power supply, a protected device, and a power protection circuit as described in the first aspect and any embodiment thereof; wherein the power protection circuit is disposed in the power supply circuit of the protected device and the power supply, one end of which is connected to the power supply and the other end of which is connected to the power interface of the protected device, for the safety protection of the protected device.

[0017] The power protection circuit described above constructs a dual overvoltage protection system for the protected equipment by setting up a primary protection circuit and a secondary protection circuit. The primary protection circuit focuses on transient overvoltage suppression, while the secondary protection circuit is responsible for monitoring and cutting off continuous overvoltage; the two complement each other functionally. When the primary protection circuit fails or has a delayed response, the secondary protection circuit can quickly intervene and execute protective actions, with a cutting-off efficiency down to the microsecond level. This ensures reliable protection of the protected equipment under various overvoltage scenarios, improving safety and reliability. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, and the same or corresponding reference numerals denote the same or corresponding parts, wherein: Figure 1 A schematic diagram of a power protection circuit according to some embodiments of this application is shown; Figure 2 A schematic diagram of a power protection circuit according to some embodiments of this application is shown; Figure 3 A schematic diagram of a power protection circuit according to some embodiments of this application is shown; Figure 4 A schematic diagram of a power protection circuit according to some embodiments of this application is shown.

[0019] Primary protection circuit: 11. Bidirectional transient voltage suppressor diode; 12. Inductor; Secondary protection circuit: 21. Voltage comparator; 22. Electronic switch; 23. Sampling resistor; 24. Current detection amplifier; 25. Controller; 26. First logic OR gate; 27. Second logic OR gate; Three-level protection circuit: 31. Fuse; The circuit includes: 41. Trigger; 42. Current-limiting resistor; 43. LED. Detailed Implementation

[0020] 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 some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be understood that the terms "comprising" and "including" used in the specification and claims of this application indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0023] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0024] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0025] Figure 1 Schematic diagrams of power protection circuits according to some embodiments of this application are shown. For example... Figure 1 As shown in the figure, this application embodiment proposes a power protection circuit 100, which may include a primary protection circuit and a secondary protection circuit.

[0026] In some embodiments, the primary protection circuit includes a bidirectional transient voltage suppressor diode 11 (Bidirectional TVS), which is connected in parallel with the power input terminal to clamp transient overvoltages of the power supply within a safe range.

[0027] Specifically, one end of the bidirectional transient voltage suppressor diode 11 is connected to the positive terminal of the power input terminal, and the other end is connected to the negative terminal of the power input terminal. When a positive or reverse transient overvoltage occurs at the power input terminal, the bidirectional transient voltage suppressor diode 11 can quickly clamp both types of transient overvoltages to a safe voltage range, preventing the protected equipment from being damaged by transient overvoltage surges.

[0028] In some embodiments, the selection of a bidirectional transient suppression diode may follow these conditions: its maximum clamping voltage is lower than the maximum withstand voltage of the protected device to ensure that the voltage of the protected device is always within a safe range during a surge event; and its peak pulse power and standard surge waveform are determined according to the surge intensity level of the application environment to ensure that the bidirectional transient suppression diode can safely dissipate the expected energy.

[0029] As an example, if the maximum withstand voltage of the protected equipment is 5.5V, and the equipment needs to meet the surge protection requirements specified in IEC 61000-4-5 Level 4 (4kV), a bidirectional transient suppression diode based on an 8 / 20μs standard surge waveform test, with a peak pulse power of 600W and a clamping voltage ≤5.5V can be selected. This selection can reliably limit overvoltage while resisting surge energy impacts of this level.

[0030] In some embodiments, the secondary protection circuit includes a voltage comparator 21 and an electronic switch 22. Specifically, in some embodiments, the non-inverting input terminal of the voltage comparator 21 is connected to the common terminal of the positive terminal of the power input terminal and the bidirectional transient voltage suppression diode 11, and the inverting input terminal is connected to a reference voltage source with a preset voltage threshold. This is used to acquire the power input voltage at the power input terminal in real time and compare it with the preset voltage threshold. When the power input voltage exceeds the preset voltage threshold, a voltage abnormality signal is output. The control terminal of the electronic switch 22 is connected to the output terminal of the voltage comparator 21. The controlled path is connected in series between the power input terminal and the protected device. In response to the voltage abnormality signal output by the voltage comparator 21, the controlled path is switched from the on state to the off state, thereby disconnecting the connection between the power supply and the protected device.

[0031] In some embodiments, the preset voltage threshold includes an overvoltage protection threshold. The overvoltage protection threshold is set to a critical value slightly higher than the rated operating voltage of the protected device. Therefore, when the voltage comparator 21 detects that the power input voltage is greater than the overvoltage protection threshold, it outputs an abnormal voltage signal, thereby triggering the electronic switch 22 to switch its controlled path from the on state to the off state, thereby cutting off the connection between the power supply and the protected device, and realizing overvoltage protection for the protected device.

[0032] As an example, when the protected device is a POS machine, its rated operating voltage is 5.0V. Based on this, the overvoltage protection threshold can be set to 5.5V. This threshold is higher than the rated operating voltage to avoid false triggering under normal fluctuations, thereby providing reliable overvoltage protection for the POS machine.

[0033] Therefore, the aforementioned secondary protection circuit can activate when the primary protection circuit fails to fully address the risk. Specifically, if the bidirectional transient voltage suppressor diode of the primary protection circuit cannot completely clamp the transient overvoltage due to excessive amplitude or duration, resulting in a residual voltage still exceeding the overvoltage protection threshold, or if a sustained overvoltage occurs that the bidirectional transient voltage suppressor diode cannot withstand, the voltage comparator of the secondary protection circuit will continuously monitor the power input voltage. When it detects that the power input voltage exceeds the preset voltage threshold, it outputs an abnormal voltage signal, thereby triggering the connected electronic switch 22 to disconnect the power supply from the protected equipment, thus further intercepting the overvoltage and preventing it from damaging the protected equipment.

[0034] In some embodiments, the electronic switch 22 includes a PMOS transistor whose gate is connected to the output of the voltage comparator 21, its source is connected to the power input, and its drain is connected to the protected device, forming a controlled path connected in series in the power supply circuit of the power supply and the protected device.

[0035] When the voltage comparator 21 detects that the power input voltage does not exceed the preset voltage threshold, its output terminal outputs a low-level normal voltage signal to the gate of the PMOS transistor, the PMOS transistor is turned on, the controlled path is established, and the power supply provides normal power to the protected device. When the voltage comparator 21 detects that the voltage input voltage exceeds the preset voltage threshold, its output terminal outputs a high-level abnormal voltage signal to the gate of the PMOS transistor, and the PMOS transistor can quickly turn off its controlled path within 1μs, thereby achieving isolation protection between the power supply and the protected device and avoiding damage from continuous overvoltage.

[0036] The above combination Figure 1 The power protection circuits of some embodiments of this application are described in detail. These circuits construct a dual overvoltage protection system for the protected equipment by setting up a primary protection circuit and a secondary protection circuit. The primary protection circuit focuses on transient overvoltage suppression, while the secondary protection circuit is responsible for monitoring and cutting off continuous overvoltage. The two circuits complement each other functionally. When the primary protection circuit fails or has a delayed response, the secondary protection circuit can quickly intervene and execute protective actions, with a cutting-off efficiency reaching the microsecond level. This ensures reliable protection of the protected equipment under various overvoltage scenarios, improving safety and reliability.

[0037] In some embodiments, the preset voltage threshold may include an undervoltage protection threshold in addition to an overvoltage protection threshold, thereby providing comprehensive voltage anomaly protection for the protected device. The undervoltage protection threshold is set slightly lower than the rated operating voltage of the protected device.

[0038] As an example, when the protected device is a POS machine, its rated operating voltage is 5.0V. Based on this, the undervoltage protection threshold can be set to 4.3V. This threshold is lower than the rated operating voltage to avoid false triggering under normal fluctuations, thereby providing reliable undervoltage protection for the POS machine.

[0039] Based on this, such as Figure 2 As shown, to achieve dual overvoltage and undervoltage protection for the protected equipment, voltage comparator 21 can be a dual-channel voltage comparator. It can be understood that this dual-channel voltage comparator has two independent comparison units, one for overvoltage monitoring and the other for undervoltage monitoring. The outputs of both comparison units need to be connected to the control terminal of electronic switch 22 via a second logic OR gate circuit 27. This allows electronic switch 22 to switch the controlled path from the ON state to the OFF state when it receives an abnormal voltage signal from either comparison unit, thereby disconnecting the power supply from the protected equipment and achieving dual overvoltage and undervoltage protection for the protected equipment.

[0040] Specifically, one comparator unit has its non-inverting input +IN1 connected to the common terminal of the power input positive terminal and the bidirectional transient voltage suppressor diode 11, and its inverting input -IN1 connected to the reference voltage source for the overvoltage protection threshold, used to monitor in real time whether the power input voltage exceeds the overvoltage protection threshold. The other comparator unit has its non-inverting input +IN2 connected to the common terminal of the power input positive terminal and the bidirectional transient voltage suppressor diode 11, and its inverting input -IN2 connected to the reference voltage source for the undervoltage protection threshold, used to monitor in real time whether the power input voltage is less than the undervoltage threshold. The outputs Out1 and Out2 of both comparator units are connected to the control terminal of the electronic switch 22 via a second logic OR gate 27. Therefore, when either comparator unit detects that the power input voltage exceeds the protection threshold, its corresponding output terminal outputs a voltage abnormality signal to the logic OR gate 27, triggering the electronic switch 22 to switch its controlled path from the ON state to the OFF state, thereby disconnecting the power supply from the protected device.

[0041] Therefore, the above dual-channel voltage comparator can achieve dual overvoltage and undervoltage protection for the protected equipment, further improving safety and reliability.

[0042] The above combination Figure 2 As shown, the secondary protection circuit in this embodiment monitors the power input voltage in real time through a dual-channel voltage comparator and compares the power input voltage with the overvoltage protection threshold and the undervoltage protection threshold, respectively. When the power input voltage is greater than the overvoltage protection threshold or the undervoltage protection threshold, the electronic switch is controlled to quickly disconnect the connection between the power supply and the protected device, providing reliable overvoltage and undervoltage dual protection for the protected device, and further effectively enhancing the safety and reliability of the protected device.

[0043] like Figure 1 As shown, in some embodiments, the primary protection circuit further includes an inductor 12, which is connected in series at the front end of the power input terminal to filter out high-frequency noise introduced in the power input voltage, suppress electromagnetic noise coupling, and reduce its impact on the protected equipment.

[0044] Specifically, as an exemplary implementation, inductor 12 can be a multilayer chip inductor. This type of inductor features small size, low parasitic resistance, and excellent high-frequency characteristics, effectively suppressing high-frequency noise. Furthermore, a multilayer chip inductor with an inductance value of 10μH can be selected to effectively suppress high-frequency noise in the tens to hundreds of MHz frequency band, suitable for high-frequency filtering at the power input, helping to improve system electromagnetic compatibility and simplify the power protection circuit structure.

[0045] like Figure 3 As shown, in some embodiments, the secondary protection circuit further includes a sampling resistor 23, a current sensing amplifier 24, and a controller (MCU) 25, forming an overcurrent protection circuit. This overcurrent protection circuit monitors changes in the power input current in real time and promptly disconnects the power supply and the protected device when an overcurrent event occurs, effectively preventing damage to the protected device due to current overload and further improving the safety and reliability of the protected device.

[0046] Furthermore, the sampling resistor 23 is connected in series in the main circuit between the positive terminal of the power input and the protected device. The input terminal of the current sensing amplifier 24 is connected in parallel with the sampling resistor 23 to collect the voltage difference across the sampling resistor 23. The input terminal of the controller 25 is connected to the output terminal of the current sensing amplifier 24 to calculate the power input current at the power input terminal based on the voltage difference output by the current sensing amplifier 24, and compares the power input current with a preset overcurrent protection threshold. When the power input current exceeds the preset overcurrent protection threshold, an abnormal current signal is output. The output terminal of the controller 25 and the voltage comparator 21 are connected to the control terminal of the electronic switch 22 through the first logic OR gate circuit 26. It can be understood that the voltage difference across the sampling resistor 23 is proportional to the power input current, and the controller 25 can calculate the power input current through the voltage difference and resistance value across the sampling resistor 23.

[0047] Therefore, when the electronic switch 22 receives the abnormal current signal output by the controller 25 and / or the abnormal voltage signal output by the voltage comparator 21, it quickly switches its own conduction state to the off state, thereby cutting off the connection between the power supply and the protected equipment and realizing overcurrent protection for the protected equipment.

[0048] In some embodiments, the electronic switch 22 includes a PMOS transistor whose gate is connected to the output of the first logic OR gate 26, and whose source is connected to the low potential end of the sampling resistor 23, and whose drain is connected to the positive terminal of the protected device, thereby forming a series controlled path between the power supply and the protected device.

[0049] When voltage comparator 21 detects that the power input voltage does not exceed the preset voltage threshold and controller 25 does not detect that the power input current does not exceed the preset overcurrent protection threshold, both output terminals output a low-level normal signal to the first logic OR gate circuit 26. The first logic OR gate circuit 26 outputs a low level to the gate of the PMOS transistor, turning on the PMOS transistor and establishing its controlled path, allowing the power supply to normally supply power to the protected device. When voltage comparator 21 detects that the power input voltage exceeds the preset voltage threshold, its output terminal outputs a high level to the first logic OR gate circuit 26, or when controller 25 detects that the power input current exceeds the preset overcurrent protection threshold, its output terminal outputs a high-level abnormal signal to the first logic OR gate circuit 26. Consequently, the first logic OR gate circuit 26 outputs a high level to the gate of the PMOS transistor, which can quickly turn off its controlled path within 1μs, thereby achieving isolation protection between the power supply and the protected device and preventing damage from continuous overvoltage or overcurrent.

[0050] In some embodiments, the sampling resistor 23 may be a resistor with low resistance, high accuracy, and a low temperature coefficient (TCR). It is understood that the low resistance characteristic helps to significantly reduce power loss and heat generation of the sampling resistor in the circuit, avoiding measurement errors introduced by its own temperature drift. Simultaneously, the high accuracy and low TCR characteristics work together to ensure that the resistance value of the sampling resistor remains stable across the entire temperature range, thereby enabling the converted voltage difference to accurately and reliably reflect changes in the power supply input current, providing an accurate basis for the overcurrent protection circuit and effectively preventing false triggering or protection failure.

[0051] Specifically, as an exemplary implementation, the sampling resistor 23 can be a precision sampling resistor with a resistance of 0.05Ω. This resistor has the characteristics of low resistance, high accuracy and low temperature coefficient (TCR), and its built-in temperature compensation circuit can effectively offset the influence of resistor temperature drift on the voltage difference sampling accuracy.

[0052] In some embodiments, the current sense amplifier 24 may employ a high-precision current sense amplifier to achieve real-time current monitoring. For example... Figure 3 As shown, the input terminals of the current sensing amplifier 24 include +IN and -IN, and the output terminal is Out. +IN is connected to the high potential terminal of the sampling resistor 23, and -IN is connected to the low potential terminal of the sampling resistor 23, thereby realizing parallel connection with the sampling resistor 23. Out is connected to the input terminal of the controller 25 to transmit the sampled voltage difference to the controller 25 for overcurrent monitoring.

[0053] In some embodiments, the preset overcurrent protection threshold includes a first overcurrent protection threshold, which is set slightly higher than the rated operating current of the protected device but lower than its maximum peak starting inrush current. This setting provides effective protection against abnormal overcurrents during operation while ensuring that the normal startup process of the protected device is not affected.

[0054] For example, when the protected device is a POS machine, its rated operating current is 2A and its maximum starting inrush current peak is 5A. Therefore, the first overcurrent protection threshold can be set to 3A. This threshold can quickly block abnormal overcurrents exceeding 3A during the operation of the protected device, thereby improving the starting compatibility and operational reliability of the protected device.

[0055] The aforementioned static threshold scheme is prone to false triggering during the startup of the protected equipment due to inrush current exceeding the first overcurrent protection threshold. To address this issue, in some embodiments, a dynamic overcurrent protection mechanism can be further introduced: the preset overcurrent protection thresholds include a first overcurrent protection threshold and a second overcurrent protection threshold. The second overcurrent protection threshold is set to be no less than the peak value of the maximum startup inrush current, allowing the startup inrush to pass.

[0056] Based on this, the controller 25 sets the overcurrent protection threshold to the first overcurrent protection threshold. The controller 25 calculates the power input current based on the voltage signal output by the current sensing amplifier 24 and compares it with the first overcurrent protection threshold in real time. When the power input current is greater than the first overcurrent protection threshold, the overcurrent protection threshold is switched to the second overcurrent protection threshold, and a timer is started to begin counting.

[0057] If the controller 25 detects that the power input current exceeds the second overcurrent protection threshold within a preset time period, it immediately outputs a current abnormality signal to control the electronic switch 22 to disconnect the power supply from the protected device. If the power input current remains below the second overcurrent protection threshold within the preset time period, normal operation is maintained. After the preset time period ends, the controller first switches the overcurrent protection threshold back to the first overcurrent protection threshold, and then immediately detects the power input current: if the current is still greater than the first overcurrent protection threshold, it is determined to be a real overcurrent fault, and an abnormal current signal is output to control the electronic switch 22 to disconnect the power supply from the protected device; if the power input current has fallen below the first overcurrent protection threshold, i.e., less than the first overcurrent protection threshold, normal operation is maintained.

[0058] Therefore, through the above-mentioned dynamic threshold management mechanism, while avoiding false triggering by startup impact, it is possible to effectively identify and block continuous overcurrent faults, thereby improving the startup compatibility and reliability of the protected equipment.

[0059] In some embodiments, the preset duration can be determined based on the duration of the maximum expected startup impact of the protected device, aiming to cover the entire process during normal startup while avoiding excessive delay that could affect the response speed to actual overcurrent faults. For example, the preset duration can be set to a duration less than or equal to 10 ms.

[0060] The above combination Figure 3 The secondary protection circuit of this application embodiment is further described in detail. This secondary protection circuit further integrates an overcurrent protection circuit consisting of a sampling resistor, a current detection amplifier, and a controller. It can quickly disconnect the power supply from the protected device when an overcurrent is detected in the circuit, thereby achieving overcurrent protection for the protected device and further effectively enhancing the safety and reliability of the protected device.

[0061] like Figure 1 As shown, in some embodiments, the power protection circuit 0 further includes a three-level protection circuit, which includes a fuse 31 connected in series between the output terminal of the electronic switch 22 and the protected device. When the electronic switch 22 fails, i.e., the two-level protection circuit fails and there is an overcurrent, the connection between the power supply and the protected device is cut off, thereby further intercepting the overcurrent, preventing damage to the protected device, and further enhancing the safety and reliability of the protected device.

[0062] As described above, the electronic switch 22 is a PMOS transistor with its output terminal being the drain. Therefore, the fuse 31 is connected in series between the drain of the PMOS transistor and the positive terminal of the protected device.

[0063] In some embodiments, fuse 31 is a self-resetting fuse, which can switch to a high configuration to quickly disconnect the connection between the power supply and the protected device when an overcurrent fault occurs, and automatically restore the connection between the power supply and the protected device after the fault is cleared, without the need for manual replacement or restart, thus automating the maintenance process.

[0064] The above combination Figure 4 The power protection circuit of this application embodiment is further described, which sets up a three-level protection circuit to provide a final safety barrier when the first-level and second-level protection circuits fail. The first-level protection circuit performs primary filtering of transient overvoltages. The second-level protection circuit, as a fast-response main protection, achieves accurate detection and shutdown protection against continuous overvoltage, overcurrent, and undervoltage, with a shutdown efficiency reaching the microsecond level. Finally, in extreme fault conditions, the third-level protection circuit permanently or temporarily disconnects the connection between the power supply and the protected equipment through irreversible physical melting or recoverable high-resistance shutdown, fundamentally eliminating the risk of damage to the protected equipment and enhancing its safety and reliability.

[0065] like Figure 4As shown, in some embodiments, the power protection circuit 100 further includes a prompting circuit consisting of a trigger 41 and / or a current-limiting resistor 42 and an LED 43. The input of the trigger 41 is connected to the output of the first logic OR gate circuit 26, and its output is connected to the main control device and, through the current-limiting resistor 42, to the anode of the LED 43.

[0066] Therefore, when the first logic OR gate 26 outputs an abnormal signal (corresponding to the voltage comparator 21 outputting an abnormal voltage signal and the controller 25 outputting an abnormal current signal), the trigger 41 enters the latch state and outputs a high level, thereby sending an alarm signal to the main control device and lighting up the LED 43, so as to realize the visualization and remote monitoring of the fault status.

[0067] The above combination Figure 4 The power protection circuit of the embodiments of this application is further described in an expanded manner. By adding a prompting circuit, the fault state is latched when the voltage or current is abnormal, and a remote alarm signal is sent to the main control device at the same time, and a local LED visual indication is provided. This realizes the dual alarm function of remote reporting of fault state and on-site prompting, which significantly improves the detectability and maintainability of faults in the protected equipment.

[0068] Some embodiments of this application also provide a power protection system, which includes a power supply, a protected device, and a power protection circuit of any of the above embodiments. The power protection circuit is disposed in the power supply circuit between the protected device and the power supply, with one end connected to the power supply and the other end connected to the power interface of the protected device, for the safety protection of the protected device.

[0069] Therefore, the power protection circuit can provide comprehensive protection against abnormal situations such as transient overvoltage, continuous overvoltage, continuous undervoltage, and overcurrent that occur when the protected equipment is hot-swapped, ensuring the safe and stable operation of the precision electronic components inside the protected equipment. At the same time, it can also effectively prevent the loss or error of transaction data due to power problems, thus effectively enhancing the safety and reliability of the protected equipment.

[0070] In some embodiments, the protected device may be a payment terminal device such as a POS machine, or other electronic devices that have high requirements for power stability, such as IoT terminals, industrial control equipment or communication modules, etc. This embodiment does not specifically limit this.

[0071] While numerous embodiments of this application have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will arise for those skilled in the art without departing from the spirit and intent of this application. It should be understood that various alternatives to the embodiments of this application described herein may be employed in the practice of this application. The appended claims are intended to define the scope of protection of this application and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A power supply protection circuit, characterized in that, include: Primary protection circuit and secondary protection circuit; among which, The primary protection circuit includes a bidirectional transient voltage suppression diode (11), which is connected in parallel with the power input terminal to clamp the transient overvoltage of the power supply within a safe range; The secondary protection circuit includes a voltage comparator (21) and an electronic switch (22); wherein, The non-inverting input terminal of the voltage comparator (21) is connected to the common terminal of the positive terminal of the power input terminal and the bidirectional transient voltage suppressor diode (11), and the inverting input terminal is connected to the reference voltage source of the preset voltage threshold. It is used to collect the power input voltage of the power input terminal in real time and compare it with the preset voltage threshold. When the power input voltage exceeds the preset voltage threshold, it outputs a voltage abnormality signal. The control terminal of the electronic switch (22) is connected to the output terminal of the voltage comparator (21). The controlled path is connected in series between the power input terminal and the protected device. It is used to respond to the voltage abnormality signal output by the voltage comparator (21) and switch the controlled path from the on state to the off state, thereby cutting off the connection between the power supply and the protected device.

2. The power protection circuit according to claim 1, characterized in that, The electronic switch (22) includes a PMOS transistor; wherein, The gate of the PMOS transistor is connected to the output terminal of the voltage comparator (21); The source of the PMOS transistor is connected to the power input terminal, and the drain is connected to the protected device, forming a controlled path connected in series in the power supply circuit of the power source and the protected device.

3. The power protection circuit according to claim 1, characterized in that, The primary protection circuit also includes an inductor (12), which is connected in series at the front end of the power input terminal to filter out high-frequency noise introduced in the power input voltage.

4. The power protection circuit according to claim 3, characterized in that, The inductor (12) includes a multilayer chip inductor.

5. The power protection circuit according to claim 1, characterized in that, The secondary protection circuit also includes a sampling resistor (23), a current detection amplifier (24), a controller (25), and a first logic OR gate circuit (26); wherein, The sampling resistor (23) is connected in series in the main circuit between the positive terminal of the power input and the protected device; The input terminal of the current sensing amplifier (24) is connected in parallel with the sampling resistor (23) to collect the voltage difference across the sampling resistor (23); The input terminal of the controller (25) is connected to the output terminal of the current detection amplifier (24) and is used to calculate the power input current of the power input terminal based on the voltage difference output by the current detection amplifier (24), compare the power input current with the preset overcurrent protection threshold, and output an abnormal current signal when the power input current exceeds the preset overcurrent protection threshold. The output terminal of the controller (25) and the voltage comparator (21) are connected to the control terminal of the electronic switch (22) through a first logic OR gate circuit (26); When the electronic switch (22) receives the current abnormal signal output by the controller (25) and / or receives the voltage abnormal signal output by the voltage comparator (21), it switches the controlled path from the on state to the off state, thereby cutting off the connection between the power supply and the protected device.

6. The power protection circuit according to claim 5, characterized in that, The electronic switch (22) includes a PMOS transistor; wherein, The gate of the PMOS transistor is connected to the output of the first logic OR gate (26). connect; The source of the PMOS transistor is connected to the low potential end of the sampling resistor (23). The drain is connected to the positive terminal of the protected device, thereby forming a series controlled path between the power supply and the protected device.

7. The power protection circuit according to claim 1, characterized in that, It also includes a three-level protection circuit; among which, The three-level protection circuit includes a fuse (31), which is connected in series between the output terminal of the electronic switch (22) and the protected device, and is used to disconnect the connection between the power supply and the protected device when the electronic switch (22) fails and there is an overcurrent.

8. The power protection circuit according to claim 7, characterized in that, The fuse (31) is a resettable fuse, which is used to disconnect the connection between the power supply and the protected device when the electronic switch (22) fails and there is an overcurrent, and automatically reconnects after normal operation to restore the connection between the power supply and the protected device.

9. The power protection circuit according to claim 1, characterized in that, It also includes a notification circuit, which includes a trigger (41) and / or a current-limiting resistor (42) and an LED (43); wherein, The input terminal of the flip-flop (41) is connected to the output terminal of the first logic OR gate circuit (26), and the output terminal is connected to the main control device and the anode of the LED lamp (43) through the current limiting resistor (42); When the first logic OR gate (26) outputs an abnormal signal, the flip-flop (41) enters the latch state and outputs a high level, sending an alarm signal to the main control device and lighting up the LED (43).

10. A power protection system, characterized in that, include: Power supply, protected equipment, and power protection circuit as described in any one of claims 1 to 9; wherein, The power protection circuit is installed in the power supply circuit of the protected device and the power supply. One end of the circuit is connected to the power supply, and the other end is connected to the power interface of the protected device, for the safety protection of the protected device.

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