Under-voltage protection circuit and device

Abstract

The utility model discloses an under-voltage protection circuit and device, and relates to the technical field of under-voltage protection, and the under-voltage protection circuit comprises a sampling module, a comparison module and a logic action module which are connected in sequence, and a self-locking recovery module which is connected with the comparison module and the logic action module. Under-voltage protection is provided through the sampling module, the comparison module and the logic action module; after the logic action module triggers under-voltage protection, if the under-voltage time of the monitoring voltage is smaller than the preset locking time, the logic action module enters a self-locking state, the state of the output signal is kept unchanged so as to achieve self-locking, and when the under-voltage time reaches the preset locking time, the self-locking recovery module controls the logic action module to release the self-locking state so as to achieve self-locking. And entering a normal working state changing along with the monitoring voltage so as to realize self-locking recovery. According to the invention, the self-locking function and the recovery function of undervoltage protection can be realized under the condition of rapid voltage oscillation, and the circuit stability and the undervoltage protection effect are improved.

Description

Technical Field

[0001] The present application relates to the technical field of undervoltage protection, and in particular to an undervoltage protection circuit and device. Background Art

[0002] In the hardware circuit of the product, the undervoltage protection function is very common and necessary. It can prevent functional failures caused by low voltage from causing damage to the hardware components of the product, and can protect the safety of the entire hardware product. Therefore, it is widely used in various fields.

[0003] Most of the undervoltage protection circuits in the related art use a comparator to perform undervoltage judgment on the collected device voltage. When the input voltage drops for a short time and then recovers, that is, a rapid voltage oscillation occurs, the output state of the circuit will change instantly and synchronously with the change of the input voltage. Since the time from the voltage oscillation to the recovery is short, the subsequent device that receives and processes the output signal may not have enough time to perform related operations, and cannot meet more requirements of the undervoltage protection function, thereby affecting the undervoltage protection effect. Utility Model Content

[0004] The main purpose of the present application is to propose an undervoltage protection circuit and device, aiming to solve the technical problem that the undervoltage protection circuit in the related art does not have a self-locking function for rapid voltage oscillations.

[0005] To achieve the above object, the present application proposes an undervoltage protection circuit, the circuit comprising a sampling module, a comparison module and a logic action module connected in sequence, and a self-locking recovery module connected to the comparison module and the logic action module respectively;

[0006] The sampling module is used to perform voltage division sampling on the actual monitoring voltage and output the sampled voltage;

[0007] A comparison module, used to compare the sampled voltage with a preset undervoltage threshold, and output a corresponding comparison signal according to the comparison result;

[0008] A logic action module, used for performing logic processing according to the comparison signal to provide output signals of different states; and, after triggering the undervoltage protection, if the undervoltage time of the monitored voltage is less than the preset lock time, entering the self-locking state to maintain the state of the output signal unchanged;

[0009] The self-locking recovery module is used to control the logic action module to release the self-locking state and enter the normal working state following the monitoring voltage change when the undervoltage time reaches the preset locking time.

[0010] In one embodiment, the logic action module includes a first logic unit, a second logic unit, and a third logic unit;

[0011] The input end of the first logic unit is respectively connected to the output end of the comparison module and the input end of the self-locking recovery module, the input end of the second logic unit is connected to the output end of the first logic unit, the first output end of the second logic unit is connected to the input end of the first logic unit, and the second output end of the second logic unit is respectively connected to the input end of the third logic unit and the control end of the self-locking recovery module.

[0012] In one embodiment, the first logic unit is used to generate a first logic signal according to the comparison signal, and output the first logic signal to the input end of the second logic unit;

[0013] A second logic unit is used to generate a second logic signal and a synchronization logic signal according to the first logic signal, and output the second logic signal to the input end of the third logic unit and the control end of the self-locking recovery module, and output the synchronization logic signal to the input end of the first logic unit;

[0014] A third logic unit, configured to generate and output an output signal according to the second logic signal;

[0015] The first logic unit is further configured to enter a self-locking state according to a synchronous logic signal when the undervoltage time of the monitored voltage is less than a preset locking time, and maintain the state of the first logic signal unchanged, so that the logic action module maintains the state of the output signal unchanged;

[0016] The self-locking recovery module is used to control itself to conduct according to the second logic signal when the undervoltage time reaches the preset locking time, so that the first logic unit releases the self-locking state and enters a normal working state following the monitoring voltage change.

[0017] In one embodiment, the sampling module includes a resistor RU, a resistor RD and a capacitor C1;

[0018] One end of the resistor RU is connected to the target device, the other end of the resistor RU is respectively connected to one end of the resistor RD, one end of the capacitor C1 and the comparison module, and the other end of the resistor RD and the other end of the capacitor C1 are both grounded.

[0019] In one embodiment, the comparison module includes a reference source TL, a voltage zener diode ZD1, a resistor R1, a resistor R2 and a capacitor C2;

[0020] The control end of the reference source TL is connected to the sampling module, the input end of the reference source TL is respectively connected to one end of the resistor R1 and the cathode of the voltage-stabilizing diode ZD1, the other end of the resistor R1 is connected to the working power supply, the anode of the voltage-stabilizing diode ZD1 is respectively connected to one end of the resistor R2, one end of the capacitor C2 and the logic action module, and the output end of the reference source TL, the other end of the resistor R2 and the other end of the capacitor C2 are all grounded.

[0021] In one embodiment, the first logic unit includes a transistor Q1, a resistor R3, a resistor R4 and a capacitor C3;

[0022] The base of the transistor Q1 is respectively connected to the output end of the comparison module, the input end of the self-locking recovery module and the first output end of the second logic unit, the emitter of the transistor Q1 is grounded, the collector of the transistor Q1 is respectively connected to one end of the resistor R3, one end of the capacitor C3 and the input end of the second logic unit through the resistor R4, and the other end of the resistor R3 and the other end of the capacitor C3 are respectively connected to the pull-up power supply.

[0023] In one embodiment, the second logic unit includes a transistor Q2, a resistor R5, and a resistor R6;

[0024] The base of the transistor Q2 is connected to the output end of the first logic unit, the emitter of the transistor Q2 is connected to the pull-up power supply, the collector of the transistor Q2 is respectively connected to one end of the resistor R5 and the input end of the third logic unit, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and the input end of the first logic unit, and the other end of the resistor R6 is grounded.

[0025] In one embodiment, the third logic unit includes a transistor Q3, a resistor R7 and a resistor R8;

[0026] The base of transistor Q3 is connected to the second output terminal of the second logic unit through resistor R7, the emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to one end of resistor R8 and the target device respectively, and the other end of resistor R8 is connected to the pull-up power supply.

[0027] In one embodiment, the self-locking recovery module includes a transistor Q4, a resistor R9 and a capacitor C4;

[0028] The base of the transistor Q4 is respectively connected to one end of the resistor R9 and one end of the capacitor C4, the collector of the transistor Q4 is respectively connected to the output end of the comparison module, the input end of the first logic unit and the first output end of the second logic unit, the other end of the resistor R9 is connected to the second output end of the second logic unit, and the emitter of the transistor Q4 and the other end of the capacitor C4 are both grounded.

[0029] In addition, to achieve the above purpose, the present application also proposes an undervoltage protection device, comprising:

[0030] Such as the undervoltage protection circuit mentioned above.

[0031] One or more technical solutions proposed in this application have at least the following technical effects:

[0032] An undervoltage protection circuit is proposed, including a sampling module, a comparison module, a logic action module and a self-locking recovery module. In the circuit, the sampling module performs voltage division sampling on the actual monitoring voltage and outputs the sampled voltage. The comparison module compares the sampled voltage with a preset undervoltage threshold and outputs a corresponding comparison signal according to the comparison result. The logic action module performs logic processing according to the comparison signal to provide output signals of different states, so as to provide undervoltage protection when the target device is undervoltage. After the undervoltage protection is triggered by the logic action module, if the undervoltage time of the monitoring voltage is less than the preset locking time, the self-locking state is entered to maintain the state of the output signal unchanged to achieve self-locking. The self-locking recovery module also performs logic processing according to the comparison signal to provide output signals of different states in order to provide undervoltage protection when the target device is undervoltage. When the time reaches the preset locking time, the control logic action module releases the self-locking state and enters a normal working state that follows the changes in the monitored voltage to achieve self-locking recovery, thereby realizing the self-locking and recovery of the undervoltage protection circuit; in the case of rapid voltage oscillation, the circuit can realize the self-locking function and recovery function of the undervoltage protection, improve the circuit stability and undervoltage protection effect, and can maintain the logic state of the output signal for a period of time, so that the target device can perform other related operations of the undervoltage protection within this time, and realize more functional expansion; at the same time, the circuit structure is simple and can be implemented by some basic electronic components such as transistors, resistors, and voltages, so it also has a low cost effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a connection block diagram of the first embodiment of the undervoltage protection circuit of the present application;

[0036] Figure 2 A circuit schematic diagram of an undervoltage protection circuit provided in an embodiment of the present application;

[0037] Figure 3 for Figure 2 Detailed connection diagram of the logic action module;

[0038] Figure 4 A schematic diagram of a logic change of the input signal Uin and the output signal Uout provided in this embodiment;

[0039] Figure 5This is another logical change diagram of the input signal Uin and the output signal Uout provided in this embodiment.

[0040] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0042] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application, the directional indication is only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture. If the specific posture changes, the directional indication will also change accordingly. If there are descriptions of "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, scheme B, or schemes that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0043] In the hardware circuit of the product, the undervoltage protection (UVP) function is very common and necessary. The undervoltage protection circuit in the related technology is generally composed of three units. First, the actual monitored device voltage is sampled by the sampling unit, and the sampled voltage is output to the comparison unit; the comparison unit generally uses a comparator, and when the actual device voltage is lower than the set value, the comparator flips; finally, the logic unit makes judgments and protections; wherein, the logic unit can provide the output signal to the processor.

[0044] Analysis of related technologies found that in the undervoltage protection circuit that uses a comparator to judge the undervoltage of the collected device voltage, since the general comparator has an uncertain output state when the power supply voltage is lower than the required value during the power-on process, this may cause the logic unit to activate faster, resulting in serious malfunction of the undervoltage protection circuit; even if a comparator with a built-in power-on reset (POR, Power-onReset) function is used, it is always at a low level before the voltage is established, which is easy to affect the operation of subsequent logic units, and may also cause the undervoltage protection circuit to malfunction.

[0045] In addition, for the undervoltage protection circuit in the above-mentioned related technology, when the input voltage drops for a short time and then recovers, that is, a rapid voltage oscillation is generated, the output state of the circuit will change synchronously with the change of the input voltage. Since the time from the occurrence of voltage oscillation to recovery is short, it may cause the subsequent device that receives and processes the output signal to not have enough time to perform fault recording, trigger protection and other related operations, and cannot meet more requirements of the undervoltage protection function, thereby affecting the undervoltage protection effect.

[0046] Therefore, the undervoltage protection circuit in the related art has the problem of easy misoperation and lack of self-locking function for fast voltage oscillation. In view of the above problems, the present application proposes an undervoltage protection circuit and device.

[0047] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0048] The present application embodiment provides an undervoltage protection circuit, referring to Figure 1 , Figure 1 This is a connection block diagram of the first embodiment of the undervoltage protection circuit of the present application.

[0049] In this embodiment, the undervoltage protection circuit includes a sampling module 10, a comparison module 20 and a logic action module 30 connected in sequence, and a self-locking recovery module 40 connected to the comparison module 20 and the logic action module 30 respectively;

[0050] The sampling module 10 is used to perform voltage division sampling on the actual monitoring voltage and output the sampled voltage;

[0051] A comparison module 20, used to compare the sampled voltage with a preset undervoltage threshold, and output a corresponding comparison signal according to the comparison result;

[0052] The logic action module 30 is used to perform logic processing according to the comparison signal to provide output signals of different states; and to enter a self-locking state to maintain the state of the output signal unchanged if the undervoltage time of the monitored voltage is less than a preset locking time after the undervoltage protection is triggered;

[0053] The self-locking recovery module 40 is used to control the logic action module 30 to release the self-locking state and enter a normal working state following the change of the monitored voltage when the undervoltage time reaches a preset locking time.

[0054] It should be noted that the undervoltage protection circuit can be applied to a target device, which refers to a device that needs to monitor voltage changes. The actual monitoring voltage refers to the voltage corresponding to the voltage signal actually monitored by the target device. The monitoring voltage will be input to the undervoltage protection circuit, that is, the target device can provide an input signal Uin containing the monitoring voltage to the undervoltage protection circuit. The sampling module 10 performs voltage division sampling on the actual monitoring voltage, that is, the voltage of the target device, and outputs a sampling signal containing the sampling voltage; the comparison module 20 compares the sampling signal with the reference signal, specifically compares the sampling voltage in the sampling signal with the preset undervoltage threshold in the reference signal, and outputs a corresponding comparison signal according to the comparison result, including a high-level signal or a low-level signal; the logic action module 30 performs logic processing according to the comparison signal to obtain an output signal Uout in different states, including a low-level state or a high-level state, to provide to the target device, and specifically, the output signal Uout can be provided to the processor or controller in the target device, so that it can control related devices such as switch tubes, contactors, etc. to perform protection actions based on the state of the output signal Uout, thereby preventing the corresponding functional failure caused by the voltage being too low, and achieving the purpose of providing undervoltage protection when the target device is undervoltage.

[0055] On this basis, the logic action module 30 can enter a self-locking state through internal logic processing after triggering the undervoltage protection, if the undervoltage time of the monitored voltage is less than the preset locking time, and maintain the state of the output signal Uout unchanged to achieve undervoltage protection self-locking; the self-locking recovery module 40 can control the logic action module 30 to maintain self-locking within a certain period of time, that is, when the undervoltage time of the target device is less than the preset locking time. When the undervoltage time of the target device reaches the preset locking time, the logic action module 30 is controlled to change the state of the output signal Uout to release the self-locking state. The logic action module 30 will switch from the undervoltage protection self-locking state to a normal working state that follows the changes in the monitored voltage to achieve undervoltage protection self-locking recovery, so that the undervoltage protection circuit has self-locking function and recovery function.

[0056] Exemplarily, when the voltage (monitoring voltage) of the monitored target device is normal, the comparison signal obtained by the comparison module 20 may be a low level, and the logic state of the output signal Uout corresponding to the output of the logic action module 30 is 1; when the monitoring voltage is undervoltage, the comparison signal obtained by the comparison module 20 is a high level, and the logic action module 30 provides an output signal Uout with a logic state of 0. At this time, the input of the logic action module 30 maintains a high level under its own logic processing to maintain the output signal Uout with a logic state of 0, that is, self-locking is achieved. Specifically, if the monitoring voltage is undervoltage for a short time and then recovers, the comparison signal obtained by the comparison module 20 becomes a low level, but in the logic processing of the logic action module 30 itself, the comparison signal is turned off. Under this condition, the actual input of the logic action module 30 is still at a high level, so that the state of the output signal Uout can be maintained at 0, until the self-locking recovery module 40 passes a certain period of time, specifically when the undervoltage time reaches the preset locking time, the logic action module 30 is controlled to release the self-locking state, so that the actual input of the logic action module 30 is a low-level comparison signal, and the logic state of the output signal Uout corresponding to the output of the logic action module 30 changes from 0 to 1, and enters a normal working state that follows the change of the monitoring voltage. That is, at this time, the self-locking recovery module 40 can control the input of the logic action module 30 to correspond to the actual and become a low level, so that the logic action module 30 changes the state of the output signal Uout to 1, that is, self-locking recovery is achieved.

[0057] It can be understood that an undervoltage protection circuit with a self-locking function and a self-locking recovery function is proposed. After the circuit is powered on, undervoltage protection is performed based on the sampled monitoring voltage, and the protection function is stable; after the undervoltage protection is triggered, based on the self-locking function, the output signal in a specific state can be stably output for a period of time, and the state of the output signal will not be changed accordingly when the monitoring voltage changes rapidly, so that the subsequent device receiving the output signal has enough time to perform related operations, and has a better undervoltage protection effect; afterward, based on the self-locking recovery function, it can be self-recovered according to the actual monitoring voltage, so that the output signal changes with the monitoring voltage. This circuit is not only stable in function, but also has good applicability.

[0058] In one possible implementation, refer to Figure 2 , Figure 2 The circuit schematic diagram of the undervoltage protection circuit provided in this embodiment; in the undervoltage protection circuit, the sampling module 10 includes a resistor RU, a resistor RD and a capacitor C1;

[0059] One end of the resistor RU is connected to the target device, and the other end of the resistor RU is respectively connected to one end of the resistor RD, one end of the capacitor C1 and the comparison module 20 , and the other end of the resistor RD and the other end of the capacitor C1 are both grounded.

[0060] It should be noted that the sampling module 10 performs voltage sampling on the input signal Uin, and the resistor RU and the resistor RD form a voltage-dividing resistor network. The sampling signal is obtained through the proportional transformation of the voltage-dividing resistor network, that is, Figure 2 The voltage at point a is Va, and then the sampling signal is output to the comparison module 20.

[0061] It can be understood that the sampling module has a simple circuit structure, does not require an additional power supply, and has a relatively low cost. It can also be applied to a wider frequency range, allowing it to work effectively in a variety of application scenarios. In addition, by adjusting the resistance value and ratio of the resistor, the voltage division ratio can be flexibly adjusted to meet different voltage sampling requirements, which has a high flexibility effect.

[0062] In a possible implementation, continue to refer to Figure 2 In the undervoltage protection circuit, the comparison module 20 includes a reference source TL, a voltage zener diode ZD1, a resistor R1, a resistor R2 and a capacitor C2;

[0063] The control end of the reference source TL is connected to the sampling module 10, the input end of the reference source TL is respectively connected to one end of the resistor R1 and the cathode of the voltage-stabilizing diode ZD1, the other end of the resistor R1 is connected to the working power supply, the anode of the voltage-stabilizing diode ZD1 is respectively connected to one end of the resistor R2, one end of the capacitor C2 and the logic action module 30, and the output end of the reference source TL, the other end of the resistor R2 and the other end of the capacitor C2 are all grounded.

[0064] It should be noted that the comparison module 20 is composed of a reference source TL and a Zener tube branch connected in parallel thereto, and is powered by a working power supply VCC. The voltage regulator diode ZD1 is also called a Zener tube, and the voltage regulator diode ZD1, the resistor R1 and the resistor R2 constitute a Zener tube branch, wherein the resistor R1 and the resistor R2 are both current limiting resistors.

[0065] In this embodiment, the working principle of the comparison module 20 is that when the sampling signal, i.e., the voltage Va at point a is greater than the reference voltage of the reference source TL, the reference source TL is approximately a pass-through. At this time, the voltage Vb at point b is lower than the conduction voltage drop of the voltage-stabilizing diode ZD1, so the Zener tube branch is cut off and a low-level comparison signal is output, i.e. Figure 2 The voltage Vc at point c is at a low level; when the sampling signal, i.e., the voltage Va at point a, is less than the reference voltage of the reference source TL, i.e., the voltage of the input signal Uin is lower than the undervoltage protection point, the reference source TL is approximately cut off. At this time, since the working power supply VCC is greater than the breakdown voltage of the voltage regulator diode ZD1, the Zener branch is turned on and a high-level comparison signal is output, i.e., the voltage Vc at point c is at a high level, for example, a comparison signal greater than 0.7V of the base of the transistor Q1 is output.

[0066] It can be understood that the reference source TL has extremely high accuracy and stability. Using the reference source for voltage comparison can ensure the accuracy of the comparison result. Moreover, due to the stability of the reference source TL, it provides a reliable reference point for comparison with the voltage corresponding to the sampling signal, so that the comparison module can maintain consistent performance under various environmental conditions. In addition, the use of the reference source TL can simplify the circuit structure of the comparison module, making the overall circuit easier to expand and maintain, and the stability and reliability of the reference source TL also help reduce circuit failures and maintenance costs.

[0067] In one possible implementation, refer to Figure 3 , Figure 3 Detailed connection diagram of the logic action module 30 in this embodiment; in the undervoltage protection circuit, the logic action module 30 includes a first logic unit 31, a second logic unit 32 and a third logic unit 33;

[0068] The input end of the first logic unit 31 is respectively connected to the output end of the comparison module 20 and the input end of the self-locking recovery module 40, the input end of the second logic unit 32 is connected to the output end of the first logic unit 31, the first output end of the second logic unit 32 is connected to the input end of the first logic unit 31, and the second output end of the second logic unit 32 is respectively connected to the input end of the third logic unit 33 and the control end of the self-locking recovery module 40.

[0069] It should be noted that the first logic unit 31, the second logic unit 32 and the third logic unit 33 are connected in parallel. Specifically, the power supply end of the first logic unit 31, the power supply end of the second logic unit 32 and the power supply end of the third logic unit 33 are all connected to the pull-up power supply Vpull-up, and the ground end of the first logic unit 31, the ground end of the second logic unit 32 and the ground end of the third logic unit 33 are all grounded.

[0070] Among them, the first logic unit 31 is used to generate a first logic signal according to the comparison signal, and output the first logic signal to the input end of the second logic unit 32; the second logic unit 32 is used to generate a second logic signal and a synchronous logic signal according to the first logic signal, and output the second logic signal to the input end of the third logic unit 33 and the control end of the self-locking recovery module 40, and output the synchronous logic signal to the input end of the first logic unit 31; the third logic unit 33 is used to generate an output signal according to the second logic signal, and output the output signal; the first logic unit 31 is also used to enter the self-locking state according to the synchronous logic signal when the undervoltage time of the monitoring voltage is less than the preset locking time, and maintain the state of the first logic signal unchanged, so that the logic action module 30 maintains the state of the output signal unchanged; the self-locking recovery module 40 is used to control itself to be turned on according to the second logic signal when the undervoltage time reaches the preset locking time, so that the first logic unit 31 releases the self-locking state and enters a normal working state that follows the change of the monitoring voltage, and specifically adjusts the state of the first logic signal to change the state of the output signal.

[0071] Optionally, the self-locking recovery module 40 can also control itself to shut down according to the second logic signal. When the self-locking recovery module 40 is turned off, the first logic unit 31 can normally maintain the state of the first logic signal according to the synchronization logic signal to enter the self-locking state and maintain the state of the output signal unchanged; when the self-locking recovery module 40 is turned on, the input of the first logic unit 31 changes, such as from a high level to a low level, so that the state of the first logic signal can be adjusted to release the self-locking state and enter a normal working state that follows the change of the monitoring voltage.

[0072] It should be noted that each logic unit can realize the above logic functions based on simple electronic components, that is, each logic unit is a hardware logic circuit, such as a triode logic circuit. In this way, the cost of the undervoltage protection circuit can also be saved.

[0073] In one possible implementation, refer to Figure 2 and Figure 3 In the logic action module 30 of the undervoltage protection circuit, the first logic unit 31 includes a transistor Q1, a resistor R3, a resistor R4 and a capacitor C3;

[0074] The base of the transistor Q1 is respectively connected to the output end of the comparison module 20, the input end of the self-locking recovery module 40 and the first output end of the second logic unit 32, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is respectively connected to one end of the resistor R3, one end of the capacitor C3 and the input end of the second logic unit 32 through the resistor R4, and the other end of the resistor R3 and the other end of the capacitor C3 are respectively connected to the pull-up power supply.

[0075] It should be noted that the transistor Q1 , the resistor R3 and the resistor R4 in the first logic unit 31 form a transistor logic circuit, wherein the resistor R3 and the resistor R4 are both current limiting resistors.

[0076] In one possible implementation, refer to Figure 2 and Figure 3 In the logic action module 30 of the undervoltage protection circuit, the second logic unit 32 includes a transistor Q2, a resistor R5 and a resistor R6;

[0077] The base of the transistor Q2 is connected to the output end of the first logic unit 31, the emitter of the transistor Q2 is connected to the pull-up power supply, the collector of the transistor Q2 is respectively connected to one end of the resistor R5 and the input end of the third logic unit 33, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and the input end of the first logic unit 31, and the other end of the resistor R6 is grounded.

[0078] It should be noted that the transistor Q2 , the resistor R5 and the resistor R6 in the second logic unit 32 form a transistor logic circuit, wherein the resistor R5 and the resistor R6 are both current limiting resistors.

[0079] In one possible implementation, refer to Figure 2 and Figure 3 In the logic action module 30 of the undervoltage protection circuit, the third logic unit 33 includes a transistor Q3, a resistor R7 and a resistor R8;

[0080] The base of transistor Q3 is connected to the second output terminal of the second logic unit 32 through resistor R7, the emitter of transistor Q3 is grounded, the collector of transistor Q3 is connected to one end of resistor R8 and the target device respectively, and the other end of resistor R8 is connected to the pull-up power supply.

[0081] It should be noted that the transistor Q3 , the resistor R7 and the resistor R8 in the third logic unit 33 form a transistor logic circuit, wherein the resistor R7 is a base resistor and the resistor R8 is a pull-up resistor.

[0082] In this embodiment, when the comparison signal is at a low level, that is, the voltage Vc at point c is at a low level, transistors Q1, Q2, and Q3 are all in a cut-off state, the output signal Uout is a pull-up high level, and the output logic is 1; when the comparison signal is at a high level, that is, the voltage Vc at point c is at a high level, transistors Q1, Q2, and Q3 are all in a saturated conduction state, the output signal Uout is a pull-down low level, and the output logic is 0.

[0083] It can be understood that each logic unit in the logic action module is composed of triodes, and the signal amplification ability of the triode can be used to ensure the stable transmission and processing of the signal, thereby improving the anti-interference ability and reliability of the circuit; as a contactless switch, the triode has the characteristics of fast response speed and long service life, so that the logic action module can respond quickly and accurately, thereby improving the working efficiency and performance of the circuit; in addition, the logic circuit composed of triodes has high flexibility and scalability. In actual application, the circuit structure and function of each logic unit can be adjusted according to specific needs, which facilitates the expansion and upgrading of the undervoltage protection circuit.

[0084] In a possible implementation, continue to refer to Figure 2 In the undervoltage protection circuit, the self-locking recovery module 40 includes a transistor Q4, a resistor R9 and a capacitor C4;

[0085] The base of the transistor Q4 is respectively connected to one end of the resistor R9 and one end of the capacitor C4, the collector of the transistor Q4 is respectively connected to the output end of the comparison module 20, the input end of the first logic unit 31 and the first output end of the second logic unit 32, the other end of the resistor R9 is connected to the second output end of the second logic unit 32, and the emitter of the transistor Q4 and the other end of the capacitor C4 are both grounded.

[0086] It should be noted that the self-locking recovery module 40 is composed of a transistor Q4 and an RC circuit, and a resistor R9 and a capacitor C4 form an RC circuit. The collector of the transistor Q4 is connected to point c and point d respectively, and the base of the transistor Q4 is connected to point e through the RC circuit. Among them, the resistance value of the resistor R9 and the capacitance value of the capacitor C4 are adjustable, and the locking time length of the self-locking recovery module 40 performing the self-locking function, that is, the preset locking time, can be correspondingly adjusted by adjusting the resistance value of the resistor R9 and the capacitance value of the capacitor C4.

[0087] In this embodiment, the specific working principle of the undervoltage protection circuit is:

[0088] When the monitoring voltage is normal, the comparison signal output by the comparison module 20 is low level, at this time, the voltage Vc at point c is low level, the voltage Vd at point d and the voltage Ve at point e are also low level, the transistor Q4 is cut off, and has no effect on the circuit;

[0089] When the monitoring voltage is undervoltage, the comparison signal output by the comparison module 20 is high level. At this time, the voltage Vc at point c is high level, the transistor Q1 is turned on, the base of the transistor Q2 is pulled down, the transistor Q2 is turned on, and the voltage Vd at point d is high level. Since the point d is connected to the point c, the voltage Vc at point c will remain high level, and the transistors Q1 and Q2 will remain turned on, so that the entire logic action module 30 maintains the state of outputting logic 0;

[0090] When the undervoltage protection is triggered, during the process of the logic action module 30 outputting the output signal Uout of logic 0, if the undervoltage time does not reach the preset lock time, even if the monitoring voltage is restored, the Zener tube branch of the comparison module 20 is cut off, and the level state of the voltage Vc at point c will not change, thereby realizing the self-locking function; at the same time, the high level voltage Ve at point e will charge the capacitor C4 through the resistor R9;

[0091] When charging for a period of time (preset locking time) reaches the turn-on voltage of transistor Q4, for example, greater than 0.7V of the transistor base, that is, when the undervoltage time reaches the preset locking time, transistor Q4 is turned on, and the level of the voltage Vc at point c is lowered, and transistors Q1, Q2, and Q3 all return to the cut-off state, and the output logic becomes 1, thereby realizing the recovery function.

[0092] When the circuit is initialized, even if the logic action module 30 is activated before the comparison module 20, it is not affected by it and stably outputs a high level with a logic of 1, thereby avoiding the uncertainty of the output state when the comparator is powered on.

[0093] For example, in order to help understand the undervoltage protection circuit proposed in this embodiment, refer to Figure 4 and Figure 5 , an example of the logic change of the input and output of the undervoltage protection circuit is proposed, in which, Figure 4 A schematic diagram of a logic change of the input signal Uin and the output signal Uout provided in this embodiment, Figure 5 Another logical change diagram of the input signal Uin and the output signal Uout provided in this embodiment, in which t represents time; specifically:

[0094] like Figure 4 As shown, when the undervoltage time t UVp Less than the preset lock time t locl When the voltage Vc at point c is kept at a high level, the entire logic action module 30 maintains the state where the output logic of the output signal Uout is 0; at the same time, the high level voltage Ve at point e is charged to the capacitor C4 through the resistor R9, and after the preset locking time t lock When the turn-on voltage of transistor Q4 is reached, transistor Q4 is turned on, lowering the level of the voltage Vc at point c. Transistors Q1, Q2, and Q3 all resume the cut-off state, and the output logic of the output signal Uout becomes 1.

[0095] In this case, when the monitoring voltage is undervoltage, the logic states of the input signal Uin and the output signal Uout change to 0 at the same time. IVP After the monitoring voltage is restored, the logic state of the input signal Uin changes from 0 to 1, but the output logic of the output signal Uout remains at 0. When the preset locking time t is reachedlock At the end time of the monitoring voltage, the output logic of the output signal Uout changes from 0 to 1. It can be seen that the output logic recovery time of the output signal Uout is later than the actual monitoring voltage recovery time.

[0096] like Figure 5 As shown, when the undervoltage time t UVP Greater than the preset lock time t lock When the preset lock time t is reached lock At the end time of t, the monitoring voltage has not yet recovered, that is, the monitoring voltage is still undervoltage, the Zener tube branch is still in the on state, and the current flows to point c through the voltage regulator diode ZD1; the resistance value of resistor R9 is set to make the transistor Q4 work in the amplification state, then the level of point c cannot be pulled down to the ground, so that the transistor Q1 is still in the on state, and the output logic of the output signal Uout is still 0; after the monitoring voltage is restored, the Zener tube branch is cut off, the level of point c is pulled down, and the output logic of the output signal Uout is restored to 1. In other words, the undervoltage time of the monitoring voltage is t UVP Greater than the preset lock time t lock When the voltage is monitored, the output logic of the circuit changes.

[0097] In this case, when the monitoring voltage is undervoltage, the logic states of the input signal Uin and the output signal Uout become 0 at the same time. When the preset lock time t is reached, lock At the end time of undervoltage, the level at point c cannot be pulled down, transistor Q1 is still in the on state, and the output logic of the output signal Uout is still 0. UVP At the end time, the monitoring voltage is restored. At this time, the logic state of the input signal Uin changes from 0 to 1, and the output logic of the output signal Uout changes from 0 to 1 synchronously. It can be seen that the time when the output logic of the output signal Uout is restored is consistent with the time when the actual monitoring voltage is restored.

[0098] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the undervoltage protection circuit of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0099] The present embodiment provides an undervoltage protection circuit, including a sampling module, a comparison module, a logic action module and a self-locking recovery module. In the circuit, the sampling module performs voltage division sampling on the actual monitoring voltage and outputs the sampled voltage. The comparison module compares the sampled voltage with a preset undervoltage threshold and outputs a corresponding comparison signal according to the comparison result. The logic action module performs logic processing according to the comparison signal to provide output signals of different states, so as to provide undervoltage protection when the target device is undervoltage. After the undervoltage protection is triggered by the logic action module, if the undervoltage time of the monitoring voltage is less than the preset locking time, the self-locking state is entered to maintain the state of the output signal unchanged to achieve self-locking. The self-locking recovery module is also used in When the undervoltage time reaches the preset locking time, the control logic action module releases the self-locking state and enters a normal working state that follows the changes in the monitored voltage to achieve self-locking recovery, thereby realizing the self-locking and recovery of the undervoltage protection circuit; in the case of rapid voltage oscillation, the circuit can realize the self-locking function and recovery function of the undervoltage protection, improve the circuit stability and undervoltage protection effect, and can maintain the logic state of the output signal for a period of time, so that the target device can perform other related operations of the undervoltage protection within this time, and realize more functional expansion; at the same time, the circuit structure is simple and can be implemented by some basic electronic components such as transistors, resistors, and voltages, so it also has a low cost effect.

[0100] The present application also provides an undervoltage protection device, which is applied to a target device or connected to a target device to provide undervoltage protection for the target device. The undervoltage protection device includes:

[0101] Such as the undervoltage protection circuit in any implementation manner in the above embodiments.

[0102] It should be noted that the specific structure of the undervoltage protection circuit refers to the above-mentioned embodiment. The undervoltage protection device provided in this application adopts all the technical solutions of all the embodiments of the above-mentioned undervoltage protection circuit, and therefore has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0103] The above are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. An undervoltage protection circuit, characterized in that: The circuit comprises a sampling module, a comparison module and a logic action module connected in sequence, and a self-locking recovery module connected to the comparison module and the logic action module respectively; The sampling module is used to perform voltage division sampling on the actual monitoring voltage and output the sampled voltage; The comparison module is used to compare the sampled voltage with a preset undervoltage threshold and output a corresponding comparison signal according to the comparison result; The logic action module is used to perform logic processing according to the comparison signal to provide output signals of different states; And, after the undervoltage protection is triggered, if the undervoltage time of the monitored voltage is less than the preset locking time, the self-locking state is entered to maintain the state of the output signal unchanged; The self-locking recovery module is used to control the logic action module to release the self-locking state and enter a normal working state following the change of the monitoring voltage when the undervoltage time reaches the preset locking time.

2. The undervoltage protection circuit according to claim 1, characterized in that: The logic action module includes a first logic unit, a second logic unit and a third logic unit; The input end of the first logic unit is connected to the output end of the comparison module and the input end of the self-locking recovery module respectively, the input end of the second logic unit is connected to the output end of the first logic unit, the first output end of the second logic unit is connected to the input end of the first logic unit, and the second output end of the second logic unit is connected to the input end of the third logic unit and the control end of the self-locking recovery module respectively.

3. The undervoltage protection circuit according to claim 2, characterized in that: The first logic unit is used to generate a first logic signal according to the comparison signal, and output the first logic signal to an input end of the second logic unit; The second logic unit is used to generate a second logic signal and a synchronization logic signal according to the first logic signal, and output the second logic signal to the input end of the third logic unit and the control end of the self-locking recovery module, and output the synchronization logic signal to the input end of the first logic unit; The third logic unit is used to generate and output the output signal according to the second logic signal; The first logic unit is further configured to enter a self-locking state according to the synchronous logic signal when the undervoltage time of the monitoring voltage is less than a preset locking time, and maintain the state of the first logic signal unchanged, so that the logic action module maintains the state of the output signal unchanged; The self-locking recovery module is used to control itself to turn on according to the second logic signal when the undervoltage time reaches the preset locking time, so that the first logic unit releases the self-locking state and enters a normal working state following the change of the monitoring voltage.

4. The undervoltage protection circuit according to claim 3, characterized in that: The sampling module includes a resistor RU, a resistor RD and a capacitor C1; One end of the resistor RU is connected to the target device, and the other end of the resistor RU is respectively connected to one end of the resistor RD, one end of the capacitor C1 and the comparison module, and the other end of the resistor RD and the other end of the capacitor C1 are both grounded.

5. The undervoltage protection circuit according to claim 3, characterized in that: The comparison module includes a reference source TL, a voltage stabilizing diode ZD1, a resistor R1, a resistor R2 and a capacitor C2; The control end of the reference source TL is connected to the sampling module, the input end of the reference source TL is respectively connected to one end of the resistor R1 and the cathode of the voltage-stabilizing diode ZD1, the other end of the resistor R1 is connected to the working power supply, the anode of the voltage-stabilizing diode ZD1 is respectively connected to one end of the resistor R2, one end of the capacitor C2 and the logic action module, and the output end of the reference source TL, the other end of the resistor R2 and the other end of the capacitor C2 are all grounded.

6. The undervoltage protection circuit according to claim 3, characterized in that: The first logic unit includes a transistor Q1, a resistor R3, a resistor R4 and a capacitor C3; The base of the transistor Q1 is respectively connected to the output end of the comparison module, the input end of the self-locking recovery module and the first output end of the second logic unit, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is respectively connected to one end of the resistor R3, one end of the capacitor C3 and the input end of the second logic unit through the resistor R4, and the other end of the resistor R3 and the other end of the capacitor C3 are respectively connected to the pull-up power supply.

7. The undervoltage protection circuit according to claim 3, characterized in that: The second logic unit includes a transistor Q2, a resistor R5 and a resistor R6; The base of the transistor Q2 is connected to the output end of the first logic unit, the emitter of the transistor Q2 is connected to the pull-up power supply, the collector of the transistor Q2 is respectively connected to one end of the resistor R5 and the input end of the third logic unit, the other end of the resistor R5 is respectively connected to one end of the resistor R6 and the input end of the first logic unit, and the other end of the resistor R6 is grounded.

8. The undervoltage protection circuit according to claim 3, characterized in that: The third logic unit includes a transistor Q3, a resistor R7 and a resistor R8; The base of the transistor Q3 is connected to the second output end of the second logic unit through the resistor R7, the emitter of the transistor Q3 is grounded, the collector of the transistor Q3 is respectively connected to one end of the resistor R8 and the target device, and the other end of the resistor R8 is connected to a pull-up power supply.

9. The undervoltage protection circuit according to claim 3, characterized in that: The self-locking recovery module includes a transistor Q4, a resistor R9 and a capacitor C4; The base of the transistor Q4 is respectively connected to one end of the resistor R9 and one end of the capacitor C4, the collector of the transistor Q4 is respectively connected to the output end of the comparison module, the input end of the first logic unit and the first output end of the second logic unit, the other end of the resistor R9 is connected to the second output end of the second logic unit, and the emitter of the transistor Q4 and the other end of the capacitor C4 are both grounded.

10. An undervoltage protection device, characterized in that: The device comprises: An undervoltage protection circuit as claimed in any one of claims 1 to 9.

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