An overcurrent protection circuit

Abstract

The present application provides an overcurrent protection circuit, including an electrical parameter sampling circuit for sampling electrical parameters of an electrical circuit; an overcurrent detection circuit connected to the electrical parameter sampling circuit, detecting the sampling result of the electrical parameter sampling circuit and outputting an overcurrent detection result; a load detection circuit connected to the electrical circuit, detecting whether a load is connected to the electrical circuit and outputting a load detection result; a switch signal generation circuit connected to the output ends of the overcurrent detection circuit and the load detection circuit, respectively, outputting a switch signal based on the overcurrent detection result and the load detection result, the switch signal including a switch-on signal and a switch-off signal; a switch control circuit connected in series between the load and the ground terminal of the electrical circuit, switching the on-off state between the load and the ground terminal according to the switch signal. The overcurrent protection circuit provided in the present application is constructed using pure hardware, with low circuit cost, fast response, reasonable control logic, and stability and reliability.

Description

Technical Field

[0001] The present application belongs to the field of electronic circuit technology, and further relates to power circuit protection and control technology, and specifically provides an overcurrent protection circuit. Background Art

[0002] When using rechargeable battery systems such as lithium titanate batteries to power loads, in order to avoid problems such as excessive load in the power circuit due to unexpected circumstances, which may cause overcurrent discharge of the battery and cause battery damage, it is generally necessary to design a protection circuit to monitor the power circuit and provide protection when overcurrent occurs.

[0003] Currently, dedicated circuits for overcurrent protection of lithium titanate batteries, especially those with low string counts, are relatively rare on the market, and generally require separate circuit design. One possible design approach uses a single-chip microcomputer or microprocessor as the core processing component, coupled with an external ADC acquisition circuit to collect power circuit information. The microcontroller or microprocessor then analyzes and compares the collected information to determine the necessary protective actions.

[0004] However, the cost of using a single-chip microcomputer or microprocessor to build an overcurrent protection circuit is high, and it is often difficult to obtain a timely response when a sudden current change occurs in the power circuit. In addition, the single-chip microcomputer or microprocessor may have problems such as program jamming and running away during operation, resulting in the battery having an overcurrent but the protection circuit not starting to protect it.

[0005] Therefore, it is necessary to design an overcurrent protection circuit with low cost, stable working conditions and fast response speed to provide reliable protection for the power circuit. Summary of the Invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the purpose of this application is to provide an overcurrent protection circuit built using discrete devices, whose overcurrent protection mechanism is generated by pure hardware, with low circuit cost, fast response, reasonable control logic, and stable and reliable.

[0007] The embodiments of the present application can be implemented through the following technical solutions:

[0008] An overcurrent protection circuit is used to protect an electric circuit when an overcurrent occurs, comprising:

[0009] An electrical parameter sampling circuit, used for sampling electrical parameters of the power circuit;

[0010] The overcurrent detection circuit is connected to the electrical parameter sampling circuit, detects the sampling result of the electrical parameter sampling circuit and outputs the overcurrent detection result;

[0011] The load detection circuit is connected to the power circuit to detect whether a load is connected to the power circuit and output the load detection result;

[0012] A switch signal generating circuit is connected to the output terminals of the overcurrent detection circuit and the load detection circuit respectively, and outputs a switch signal based on the overcurrent detection result and the load detection result, wherein the switch signal includes an on signal and an off signal;

[0013] The switch control circuit is connected in series between the load and the ground terminal of the power circuit, and switches the on-off state between the load and the ground terminal according to the switch signal.

[0014] Furthermore, the switch signal generating circuit outputs a cut-off signal when an overcurrent occurs in the power circuit, and when the power circuit is in an open-circuit state but the load has not been removed; the switch signal generating circuit outputs a cut-off signal when an overcurrent does not occur in the power circuit, and when the power circuit is in a short-circuit state and the load has been removed.

[0015] Furthermore, the switching signal generating circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor and a thyristor; the first end of the first voltage-dividing resistor is connected to the first power supply end, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor, the second end of the second voltage-dividing resistor is connected to the anode of the thyristor, and the cathode of the thyristor is connected to the ground end; the output end of the overcurrent detection circuit is connected to the gate of the thyristor, the output end of the load detection circuit is connected to the second end of the first voltage-dividing resistor, and the anode of the thyristor is connected to the enable end of the switch control circuit.

[0016] Preferably, the electrical parameter is the terminal voltage of a sampling resistor connected in series in the power circuit; the electrical parameter sampling circuit includes a voltage follower circuit and a differential amplifier circuit for biasing, amplifying and outputting the terminal voltage.

[0017] Preferably, the overcurrent detection circuit includes a first voltage comparator; the positive input terminal of the first voltage comparator is connected to the output terminal of the differential amplifier circuit, and the negative input terminal inputs a preset first threshold voltage; the first voltage comparator outputs a high level when the terminal voltage after bias amplification is greater than the first threshold voltage, and outputs a low level when the terminal voltage after bias amplification is less than or equal to the first threshold voltage.

[0018] Furthermore, the load detection circuit includes a second voltage comparator; the negative input terminal of the second voltage comparator is connected to the load detection endpoint, the load detection endpoint is located on the power circuit between the load and the switch control circuit, and the positive input terminal of the second voltage comparator inputs a preset second threshold voltage; the second voltage comparator outputs a low level when the voltage of the load detection endpoint is greater than the second threshold voltage, and outputs a high level when the voltage of the load detection endpoint is less than or equal to the second threshold voltage.

[0019] Preferably, the load detection circuit also includes a first diode, a first grounding capacitor and a first grounding resistor; the positive electrode of the first diode is connected to the load detection terminal, and the negative electrode is connected to the negative input terminal of the second voltage comparator; the first grounding capacitor and the first grounding resistor are connected in parallel between the negative input terminal of the second voltage comparator and the ground terminal.

[0020] Preferably, the second threshold voltage is less than or equal to the power supply terminal voltage and greater than or equal to 0.8 times the power supply terminal voltage.

[0021] Preferably, the load detection circuit also includes a third voltage-dividing resistor and a fourth voltage-dividing resistor; the third voltage-dividing resistor is connected in series between the power supply end of the power-consuming circuit and the positive input end of the second voltage comparator; the fourth voltage-dividing resistor is connected in series between the positive input end of the second voltage comparator and the ground end.

[0022] Preferably, the overcurrent protection circuit further includes a potential stabilization circuit, one end of the potential stabilization circuit is connected to the output end of the switch signal generation circuit, and the other end of the potential stabilization circuit is connected to the enable end of the switch control circuit.

[0023] The overcurrent protection circuit provided by this application has at least the following beneficial effects:

[0024] The circuit is built entirely with discrete components, and the overcurrent protection mechanism for the power circuit is realized through pure hardware. It has low cost, fast overcurrent response speed, adaptability to various working environments, and stability and reliability.

[0025] The overcurrent protection circuit provided by the present application controls the disconnection and locks the circuit when an overcurrent occurs in the power circuit. It further determines whether to release the lock by monitoring whether the load has been removed. The control logic is reasonable and avoids the situation where the circuit is repeatedly turned on and off when the load is not removed.

[0026] The conduction characteristics of components such as thyristors are used to integrate overcurrent detection and load detection results to control the on and off of the power circuit, so that the overcurrent detection and load detection results respectively control the generation of switching signals at different stages, thereby achieving continuous locking of the power circuit when overcurrent occurs and automatic unlocking of the power circuit after removing the problem load. Its overcurrent protection logic is reasonable, avoiding the possibility of misoperation caused by simultaneous detection of different circuit parameters by the same circuit. The signal judgment result is accurate, the probability of misoperation is low, and the stability of the circuit operation is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of an overcurrent protection circuit according to a preferred embodiment of the present application;

[0028] Figure 2 is an overcurrent protection control logic diagram of an overcurrent protection circuit according to an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of an overcurrent protection circuit according to a preferred embodiment of the present application;

[0030] Figure 4a Detailed circuit diagram of the electrical parameter sampling circuit and the switch control circuit in the overcurrent protection circuit according to a preferred embodiment of the present application;

[0031] Figure 4b This is a specific circuit diagram of the overcurrent detection circuit, load detection circuit, switch signal generation circuit and potential stabilization circuit in the overcurrent protection circuit according to a preferred embodiment of the present application.

[0032] Numbers in the figure

[0033] 10: Electrical parameter sampling circuit, 20: Overcurrent detection circuit, 30: Load detection circuit, 40: Switch signal generation circuit, 401: First voltage-dividing resistor, 402: Second voltage-dividing resistor, 403: Thyristor, 50: Switch control circuit, 60: Load, 70: Sampling resistor, 80: Potential stabilization circuit. DETAILED DESCRIPTION

[0034] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0035] In addition, various components in the drawings are enlarged or reduced in size for ease of understanding, but this is not intended to limit the scope of protection of this application.

[0036] Words importing the singular include the plural and vice versa.

[0037] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or are the orientation or positional relationship in which the products of the embodiments of the present application are usually placed when in use, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, in the description of the present application, in order to distinguish different units, words such as first and second are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance. Their names may be different in the detailed description and claims of the present application.

[0038] The vocabulary in this specification is used to illustrate the embodiments of the present application, but is not intended to limit the present application. It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, an indirect connection through an intermediate medium, or a communication between the two components. For those skilled in the art, the specific meanings of the above terms in this application can be specifically understood.

[0039] The present application provides an overcurrent protection circuit for protecting the power circuit when the current is overcurrent. Figure 1 As shown, the power circuit is composed of a loop between the power supply terminal VCC and the ground terminal GND, which supplies power to the load 60 connected in series therewith. The power supply terminal VCC can be a rechargeable power source, such as a low-number lithium titanate battery or other rechargeable power source, or a DC power source obtained through AC-DC conversion.

[0040] During the actual circuit operation process, due to various reasons, the load 60 in the above-mentioned power circuit may fluctuate greatly and cause overcurrent in the power circuit. At this time, it is necessary to first control the power circuit to be cut off through the protection circuit, and continue to lock and monitor the circuit until the problematic load 60 is removed, and then control the power circuit to resume conduction.

[0041] Figure 1 FIG1 shows a schematic diagram of the overcurrent protection circuit proposed in this application in some preferred embodiments. Figure 1 As shown, the overcurrent protection circuit includes: an electrical parameter sampling circuit 10 , an overcurrent detection circuit 20 , a load detection circuit 30 and a switch signal generation circuit 40 .

[0042] Among them, the electrical parameter sampling circuit 10 is used to sample the electrical parameters of the power circuit, the overcurrent detection circuit 20 is connected to the electrical parameter sampling circuit 10, detects the sampling results of the electrical parameter sampling circuit 10 and outputs the overcurrent detection result; the load detection circuit 30 is connected to the power circuit, detects whether the load 60 is connected to the power circuit and outputs the load detection result; the switch signal generation circuit 40 is respectively connected to the output ends of the overcurrent detection circuit 20 and the load detection circuit 30, and outputs a switch signal based on the overcurrent detection result and the load detection result, and the switch signal includes a connection signal and a disconnection signal; the switch control circuit 50 is connected in series between the load 60 of the power circuit and the ground terminal, and switches the on-off state between the load and the ground terminal GND according to the switch signal.

[0043] The specific implementation methods and protection mechanism principles of the above-mentioned circuits are described in detail below with reference to the accompanying drawings.

[0044] In some preferred embodiments of the present application, a sampling resistor 70 is connected in series in the power circuit, and the electrical parameter is the terminal voltage across the sampling resistor 70. When an overcurrent occurs in the power circuit, the terminal voltage of the sampling circuit will also experience voltage amplification. By sampling and detecting the above-mentioned terminal voltage, it can be determined whether there is an overcurrent in the power circuit.

[0045] In some preferred embodiments of the present application, the electrical parameter sampling circuit 10 includes a voltage follower circuit and a differential amplifier circuit for biasing, amplifying, and outputting the terminal voltage. Specifically, the voltage follower circuit stably outputs a following voltage to bias the terminal voltage, and the differential amplifier circuit further differentially amplifies the biased terminal voltage, with its output terminal outputting the biased, amplified terminal voltage.

[0046] In some preferred embodiments of the present application, the overcurrent detection circuit 20 includes a first voltage comparator, wherein the positive input terminal of the first voltage comparator (corresponding to Figure 1 The terminal a1 in the circuit is connected to the output terminal of the differential amplifier circuit, and the negative input terminal inputs a preset first threshold voltage. The output terminal of the first voltage comparator (corresponding to Figure 1 The terminal a2) in the circuit outputs a high level when the bias-amplified terminal voltage is greater than the first threshold voltage, and outputs a low level when the bias-amplified terminal voltage is less than or equal to the first threshold voltage.

[0047] Specifically, during actual circuit implementation, the first threshold voltage can be calculated and determined based on the specific parameters of the power circuit, the load 60, and the sampling resistor 70, and ensure that when the current in the power circuit exceeds the expected current upper limit, the terminal voltage after bias amplification can exceed the first threshold voltage.

[0048] In some preferred embodiments of the present application, the load detection circuit 30 includes a second voltage comparator, wherein the negative input terminal of the second voltage comparator (corresponding to Figure 1 Endpoint b1 in the load detection endpoint (corresponding to Figure 1 The load detection terminal is located on the power circuit between the load 60 and the switch control circuit 50; the positive input terminal of the second voltage comparator inputs a preset second threshold voltage. The output terminal of the second voltage comparator (corresponding to Figure 1 The terminal b2) in the load detection terminal outputs a low level when the voltage of the load detection terminal is greater than the second threshold voltage, and outputs a high level when the voltage of the load detection terminal is less than or equal to the second threshold voltage.

[0049] Specifically, in the embodiments of the present application, the second threshold voltage is used to determine the potential at the P- / C- terminal. When the switch control circuit 50 is in the off state and a load 60 is present between the P- / C- terminal and the power supply terminal VCC of the power-consuming circuit, the potential at the P- / C- terminal is slightly lower than VCC. When the load 60 is removed, the potential at the P- / C- terminal becomes low. Therefore, the second threshold voltage should be set to be slightly lower than the voltage at the P- / C- terminal when the load 60 is connected and the power-consuming circuit is disconnected. Preferably, the second threshold voltage is less than or equal to the voltage of the power supply terminal VCC and greater than or equal to 0.8 times the voltage of the power supply terminal VCC.

[0050] In some preferred embodiments of the present application, Figure 1 As shown, the switch signal generating circuit 40 includes a thyristor 403, a first voltage dividing resistor 401 and a second voltage dividing resistor 402. Specifically, the first end of the first voltage dividing resistor 401 is connected to the first power supply terminal VDD, the second end of the first voltage dividing resistor 401 is connected to the first end of the second voltage dividing resistor 402 (corresponding to Figure 1 The second end of the second voltage dividing resistor 402 is connected to the anode of the thyristor 403 (corresponding to Figure 1 The terminal c4 in the thyristor 403 is connected to the cathode of the thyristor 403 (corresponding to Figure 1 The output terminal of the overcurrent detection circuit 20 is connected to the gate of the thyristor 403 (corresponding to Figure 1 The output terminal of the load detection circuit 30 is connected to the second end of the first voltage divider resistor 401, the anode of the thyristor 403 is connected to the enable terminal of the switch control circuit 50 (corresponding to Figure 1 The endpoint d1) in is connected.

[0051] Through the connection relationship between the above-mentioned circuits, the switching signal output by the switching signal generating circuit 40 and the working state of the power circuit have the following corresponding relationship:

[0052] 1) When an overcurrent occurs in the power circuit, or when the power circuit is in an off state but the load 60 has not been removed, the switch signal generating circuit 40 outputs a cutoff signal;

[0053] 2) When there is no overcurrent in the power circuit, and when the power circuit is in a short-circuit state and the load 60 has been removed, the switch signal generating circuit 40 outputs an on signal.

[0054] The switch control circuit 50 switches the on / off state between the load 60 and the ground terminal GND through the above-mentioned cut-off signal or the on-off signal, thereby controlling the cut-off or conduction of the power circuit.

[0055] Figure 2 The specific working flow diagram of the overcurrent protection circuit is shown below. Figure 1 、 Figure 2 The specific working process of the overcurrent protection circuit is described in detail.

[0056] When the power-consuming circuit is connected to the load 60 and in the normal discharge stage, the electrical parameter sampling circuit 10 continuously samples the terminal voltage of the sampling resistor 70, and the overcurrent detection circuit 20 continuously compares the bias-amplified terminal voltage with the first threshold voltage. If the terminal voltage is less than the first threshold voltage, a low level is output through a2, and the thyristor 403 of the switching signal generating circuit 40 is turned off. At this time, c2 remains at a high level, and the enable terminal d1 of the switch control circuit 50 continuously controls the terminal P- / C- and the ground terminal GND to remain conductive.

[0057] When the current in the electrical circuit increases due to various reasons, resulting in overcurrent, the terminal voltage after bias amplification exceeds the first threshold voltage, causing the output terminal a2 of the overcurrent detection circuit 20 to output a high level to c3. C3 is the gate of the thyristor 403. When the high level is high, the anode c4 and cathode c5 of the thyristor 403 are turned on.

[0058] At this time, c4 is grounded through c5 and becomes low level, so that the switch signal generating circuit 40 outputs a low level to d1 through c2, thereby causing the switch control circuit 50 to disconnect the terminal P- / C- from the ground terminal.

[0059] It should be noted that if the overcurrent protection circuit only includes the above-mentioned overcurrent detection circuit 20 but does not include the load detection circuit 30, then at this time, according to the conduction characteristics of the thyristor 403 (after the thyristor 403 is turned on, regardless of whether its gate maintains a high level, the anode and cathode will remain turned on until the current passing through the anode and cathode basically drops to 0 and then it will be turned off again), c2 will continue to output a low level to d1, so that the power circuit is continuously locked in the cut-off state. Even if the current in the power circuit drops to 0 and causes a2 of the overcurrent detection circuit 20 to become a low level again, the cut-off locked state will not be released.

[0060] After the overcurrent protection circuit enters the cutoff lockout state, there are various ways to unlock the circuit, such as automatically unlocking after a period of time using a counter or time delay, or unlocking by manual resetting. In the embodiment of the present application, unlocking is achieved by having the load detection circuit 30 detect whether the load 60 in the power circuit has been removed. Using the removal of the load 60 from the power circuit as the criterion for unlocking the protection circuit effectively prevents the protection circuit from being repeatedly disconnected due to a drop in current after the power circuit is disconnected, and then disconnected again after the power circuit is reconnected due to the presence of the problematic load.

[0061] Specifically, if Figure 1 and Figure 2 As shown, when the switch control circuit 50 disconnects the terminal P- / C- from the ground terminal GND and the load 60 has not been removed, the potential of the terminal P- / C- will be slightly lower than the voltage of the power supply terminal VCC and greater than the second threshold voltage. At this time, b2 of the load detection circuit 30 continues to output a low level. At this time, the potential of c1 is pulled down by b2, causing the current flowing through c4 and c5 to drop to 0, thereby turning off the thyristor 403 again, and c2 remains at a low level.

[0062] Furthermore, when the load 60 is removed from the power circuit, the potential of the terminal P- / C- will drop to less than the second threshold voltage. At this time, the terminal b2 outputs a high level. Since the thyristor 403 is still in the off state, the terminal b2 pulls up c2, and the switching signal generating circuit 40 outputs a high level to d1, and makes the switching control signal reconnect the terminal P- / C- and the ground terminal. Thereafter, when a normal load is re-connected to the power circuit, it re-enters the normal discharge stage with load.

[0063] It should be noted that during the normal discharge phase of the power circuit, the load detection circuit 30 also continuously obtains the terminal P- / C- potential. Since the terminal P- / C- continuously outputs a low level at this time, b2 of the load detection circuit 30 always outputs a high level.

[0064] The working mechanism of the overcurrent protection circuit is described in detail above. Through the above working mechanism, it can be seen that the overcurrent protection circuit provided by the present application is affected by different detection circuits when the power circuit is in different states. And unlike the case where the load detection circuit 30 is not provided, in the overcurrent protection circuit provided by the embodiment of the present application, after the power circuit is overcurrent and disconnected, the thyristor 403 re-enters the cut-off state, and the load detection circuit 30 takes over the control of the switch signal generating circuit 40. After the problem load is removed, the cut-off of the thyristor 403 is used to unlock the power circuit. By utilizing the different conduction characteristics presented by the gate, anode and cathode of the thyristor 403 in the switch signal generating circuit 40 under the control of different potentials and current signals, the overcurrent detection and load detection results can be used to control the generation of switch signals at different stages respectively, thereby achieving continuous locking of the power circuit when overcurrent occurs and automatic unlocking of the power circuit after removing the problem load. Its overcurrent protection logic is reasonable, avoiding the possibility of malfunction caused by the simultaneous detection of different circuit parameters by the same circuit, the signal judgment result is accurate, the probability of malfunction is low, and the stability of the circuit operation is guaranteed.

[0065] In some preferred embodiments of the present application, the load detection circuit 30 also includes a first diode, a first grounding capacitor and a first grounding resistor, wherein the positive pole of the first diode is connected to the load detection terminal, and the negative pole is connected to the negative input terminal of the second voltage comparator, and the first grounding capacitor and the first grounding resistor are connected in parallel between the negative input terminal of the second voltage comparator and the ground terminal.

[0066] In some preferred embodiments of the present application, the load detection circuit 30 further includes a third voltage-divider resistor and a fourth voltage-divider resistor. The third voltage-divider resistor is connected in series between the power supply terminal of the power-consuming circuit and the positive input terminal of the second voltage comparator; the fourth voltage-divider resistor is connected in series between the positive input terminal of the second voltage comparator and the ground terminal. By adjusting the resistance values ​​of the third and fourth voltage-divider resistors, the second threshold voltage can be flexibly adjusted to ensure that the load detection circuit 30 can accurately detect load removal.

[0067] Figure 3 The schematic diagram of the overcurrent protection circuit provided according to some preferred embodiments of the present application is shown. Figure 1 The difference is that it also includes a potential stabilization circuit 80, one end of the potential stabilization circuit 80 (corresponding to Figure 3 The terminal e1 in the switching signal generating circuit 40 is connected to the output terminal, and the other terminal (corresponding to Figure 3 The terminal e2 in the circuit is connected to the enable terminal of the switch control circuit 50. By connecting the potential stabilization circuit 80, it is possible to avoid signal fluctuations and noise causing the terminal c2 to output an erroneous switching signal, thereby ensuring the stable operation of the protection circuit.

[0068] Figure 4a Detailed circuit diagrams of the electrical parameter sampling circuit 10 and the switch control circuit 50 in the overcurrent protection circuit provided in some preferred embodiments of the present application are shown. Figure 4b Specific circuit diagrams of the electrical parameter sampling circuit 10 and the switch control circuit 50 in the overcurrent protection circuit provided according to some preferred embodiments of the present application are shown.

[0069] Specifically, the electrical parameter sampling circuit 10 samples and bias-amplifies the terminal voltage of sampling resistor R50. The voltage follower circuit, comprised of a comparator IC5B and its peripheral components, including resistors R26, R27, R30, and capacitor C5, generates a 2.2V follower voltage based on a 2.8V reference voltage. Resistors R33 and R40 provide a 2.2V voltage bias for the terminal voltage of sampling resistor R50. The differential amplifier circuit, comprised of a comparator IC5A, resistors R43, R45, and capacitor C7, is powered by a 12V power supply. The electrical parameter sampling circuit 10 outputs the bias-amplified terminal voltage to the overcurrent detection circuit 20.

[0070] The overcurrent detection circuit 20 is composed of a comparator IC6A and its peripheral components such as a resistor R44 and a capacitor C9, and is powered by a 12V power supply. The first threshold voltage is 2.8V.

[0071] The load detection circuit 30 is composed of a comparator IC6B, resistors R29, R31, R34, a capacitor C8, and a diode D3. Its positive input terminal is connected to the power supply terminal of the power-consuming circuit and is divided by R29 and R31. Its negative input terminal is connected to the terminal P- / C- through D3 and is grounded through R34.

[0072] The switch signal generating circuit 40 includes resistors R35 and R42 and a thyristor 403Q16 connected in series between a 12V power supply and a ground terminal GND.

[0073] In addition, a resistor R52 is connected in series between the anode of Q16 and the ground terminal GND.

[0074] Potential stabilization circuit 80 is composed of MOS transistors Q13 and Q14 and resistor R36, wherein the G terminal of Q13 is connected to the anode of Q16, and the G terminal of Q14 is connected to the D terminal of Q13, and the D terminal of Q14 is output to the switch control circuit 50; the D terminal of Q13 and the G terminal of Q14 are connected to the 12V power supply through R35, and their S terminals are both grounded.

[0075] The switch control circuit 50 includes a totem pole circuit formed by a resistor R25, transistors Q9 and Q10 connected in series between a 12V power supply and ground GND, and a MOS transistor Q23. The switching control circuit 50 controls the conduction and disconnection of Q23 based on the level of the D-pole output of Q14, thereby switching the connection state between the P- / C- terminal and the ground GND.

[0076] The above describes the specific implementation methods of this application in detail. Figure 4a 、 Figure 4b The specific circuit diagram shown does not constitute a limitation on the overcurrent protection circuit provided by the present application. For those skilled in the art, several improvements and modifications can be made to the present application without departing from the principles of the present application. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. An overcurrent protection circuit for protecting an electrical circuit when an overcurrent occurs, characterized in that: include: An electrical parameter sampling circuit, used for sampling electrical parameters of the power circuit; An overcurrent detection circuit is connected to the electrical parameter sampling circuit, detects the sampling result of the electrical parameter sampling circuit and outputs the overcurrent detection result; The load detection circuit is connected to the power circuit to detect whether a load is connected to the power circuit and output the load detection result; A switch signal generating circuit is connected to the output terminals of the overcurrent detection circuit and the load detection circuit respectively, and outputs a switch signal based on the overcurrent detection result and the load detection result, wherein the switch signal includes an on signal and an off signal; A switch control circuit is connected in series between the load and the ground terminal of the power circuit, and switches the on / off state between the load and the ground terminal according to the switch signal; The switch signal generating circuit includes: a first voltage-dividing resistor, a second voltage-dividing resistor, and a thyristor; a first end of the first voltage-dividing resistor is connected to a first power supply terminal, a second end of the first voltage-dividing resistor is connected to a first end of the second voltage-dividing resistor, a second end of the second voltage-dividing resistor is connected to an anode of the thyristor, and a cathode of the thyristor is connected to a ground terminal; an output end of the overcurrent detection circuit is connected to a gate of the thyristor, an output end of the load detection circuit is connected to the second end of the first voltage-dividing resistor, and an anode of the thyristor is connected to an enable terminal of a switch control circuit; The load detection circuit includes a second voltage comparator; the negative input terminal of the second voltage comparator is connected to the load detection endpoint, and the load detection endpoint is located on the power circuit between the load and the switch control circuit. The positive input terminal of the second voltage comparator inputs a preset second threshold voltage; the second voltage comparator outputs a low level when the voltage at the load detection endpoint is greater than the second threshold voltage, and outputs a high level when the voltage at the load detection endpoint is less than or equal to the second threshold voltage; the second threshold voltage is less than or equal to the power supply terminal voltage and greater than or equal to 0.8 times the power supply terminal voltage.

2. The overcurrent protection circuit according to claim 1, wherein: The switch signal generating circuit outputs a cut-off signal when an overcurrent occurs in the power circuit, or when the power circuit is in an open circuit state but the load has not been removed; The switch signal generating circuit outputs an on signal when there is no overcurrent in the power circuit and when the power circuit is in a short-circuit state and the load has been removed.

3. The overcurrent protection circuit according to claim 1, wherein: The electrical parameter is the terminal voltage of a sampling resistor connected in series in the power circuit; The electrical parameter sampling circuit includes a voltage follower circuit and a differential amplifier circuit, which are used to bias, amplify and output the terminal voltage.

4. The overcurrent protection circuit according to claim 3, wherein: The overcurrent detection circuit includes a first voltage comparator; The positive input terminal of the first voltage comparator is connected to the output terminal of the differential amplifier circuit, and the negative input terminal is input with a preset first threshold voltage; The first voltage comparator outputs a high level when the bias-amplified terminal voltage is greater than a first threshold voltage, and outputs a low level when the bias-amplified terminal voltage is less than or equal to the first threshold voltage.

5. The overcurrent protection circuit according to claim 1, wherein: The load detection circuit further includes a first diode, a first grounding capacitor and a first grounding resistor; The anode of the first diode is connected to the load detection terminal, and the cathode is connected to the negative input terminal of the second voltage comparator; The first grounding capacitor and the first grounding resistor are connected in parallel between the negative input terminal of the second voltage comparator and the ground terminal.

6. The overcurrent protection circuit according to claim 1, wherein: The load detection circuit further includes a third voltage-dividing resistor and a fourth voltage-dividing resistor; The third voltage-dividing resistor is connected in series between the power supply terminal of the power-consuming circuit and the positive input terminal of the second voltage comparator; The fourth voltage-dividing resistor is connected in series between the positive input terminal of the second voltage comparator and the ground terminal.

7. The overcurrent protection circuit according to claim 1, wherein: It also includes a potential stabilization circuit, one end of which is connected to the output end of the switch signal generation circuit, and the other end of which is connected to the enable end of the switch control circuit.

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