Protection circuit and electronic equipment

Abstract

A protection circuit and an electronic device belong to the technical field of switching circuit protection, and are characterized in that a current sampling circuit is connected with a direct current and carries out current sampling on the direct current to output a current sampling signal; the switching circuit is configured to access a driving signal and transmit direct current according to the driving signal; the clamping circuit is connected with the current sampling circuit and the switching circuit, and is configured to clamp the current of the direct current output by the switching circuit in response to the situation that the current sampling signal is greater than a first preset voltage; the clamping circuit acts immediately when the current sampling signal is larger than the preset first voltage, software logic is not needed for reaction, the protection speed is high, the clamping circuit clamps the current of the direct current output by the switching circuit, the possibility of short-time large current during short circuit is reduced, and the reliability of the circuit is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of switch circuit protection, and in particular, relates to a protection circuit and electronic equipment. Background Art

[0002] The switch circuit can be used in various power supply circuits such as solar power supply system, hard disk peak start circuit, etc. However, there is a large current when the switch circuit is short-circuited. For this, the short-circuit protection of the existing switch circuit is implemented by a single chip microcomputer.

[0003] However, there is a delay in the short-circuit protection implemented by the microcontroller. After a short circuit occurs in the switching circuit, its action time depends entirely on the speed of the microcontroller action, and the action of the microcontroller requires a certain response time. Therefore, its protection speed is slow, and there is a short-term large current during the period from the occurrence of the short circuit to the action of the microcontroller, and the reliability is low. Utility Model Content

[0004] The purpose of the present application is to provide a protection circuit and an electronic device, aiming to solve the problem of slow short-circuit protection speed and low reliability of existing switch circuits.

[0005] In one embodiment, the protection circuit comprises:

[0006] A current sampling circuit is configured to access direct current and perform current sampling on the direct current to output a current sampling signal;

[0007] a switch circuit configured to receive a drive signal and transmit the direct current according to the drive signal;

[0008] The clamping circuit is connected to the current sampling circuit and the switch circuit, and is configured to clamp the current of the direct current output by the switch circuit in response to the current sampling signal being greater than a first preset voltage.

[0009] In one embodiment, the protection circuit further includes:

[0010] a control circuit connected to the current sampling circuit and the clamping circuit and configured to output a control signal;

[0011] a driving circuit connected to the control circuit, the clamping circuit and the switch circuit, and configured to output a driving signal according to the control signal;

[0012] The control circuit is further configured to stop outputting the control signal in response to the current sampling signal being greater than the second preset voltage for the first preset time or the current sampling signal being greater than the third preset voltage for the second preset time.

[0013] In one embodiment, the protection circuit further includes:

[0014] A voltage sampling circuit, connected to the control circuit, configured to perform voltage sampling on the direct current to output a voltage sampling signal;

[0015] The control circuit is further configured to stop outputting the control signal in response to the voltage sampling signal being less than a fourth preset voltage.

[0016] In one embodiment, the protection circuit further includes:

[0017] a soft start circuit connected to the driving circuit, the clamping circuit and the switching circuit, and configured to adjust a load voltage of the switching circuit; wherein the load voltage is used to drive the switching circuit and is slowly increased to a rated voltage value;

[0018] The switch circuit is specifically configured to transmit the direct current according to the adjusted drive signal.

[0019] In one embodiment, the soft start circuit includes a ninth resistor, a tenth resistor and a first capacitor;

[0020] The direct current is transmitted via a direct current bus, the direct current bus comprises a positive direct current bus and a negative direct current bus, and the switch circuit is connected in series to the negative direct current bus;

[0021] The first end of the ninth resistor serves as a load voltage input end of the soft start circuit, and is connected to the drive circuit to input the load voltage; the second end of the ninth resistor and the first end of the first capacitor serve together as an adjusted drive signal output end of the soft start circuit, and are connected to the switch circuit and the clamp circuit to output the adjusted drive signal; the second end of the first capacitor is connected to the first end of the tenth resistor, and the second end of the tenth resistor is connected to the negative DC bus.

[0022] In one embodiment, the control circuit includes a microprocessor;

[0023] The first general input / output terminal of the microprocessor serves as the voltage sampling signal input terminal of the control circuit to input the voltage sampling signal; the second general input / output terminal of the microprocessor serves as the current sampling signal input terminal of the control circuit to be connected to the current sampling circuit to input the current sampling signal; the third general input / output terminal of the microprocessor serves as the control signal output terminal of the control circuit to be connected to the drive circuit to output the control signal.

[0024] In one embodiment, the driving circuit includes a first transistor, a second transistor, a second resistor, a third resistor and a fourth resistor;

[0025] The direct current is transmitted via a direct current bus, the direct current bus comprises a positive direct current bus and a negative direct current bus, and the switch circuit is connected in series to the negative direct current bus;

[0026] The base of the first transistor and the first end of the second resistor serve together as a control signal input end of the drive circuit, and are connected to the control circuit to input the control signal; the collector of the first transistor is connected to the base of the second transistor and the first end of the third resistor, and the collector of the second transistor and the first end of the fourth resistor serve together as a drive signal output end of the drive circuit, and are connected to the switch circuit to output the drive signal; the second end of the third resistor is connected to the second end of the fourth resistor and the positive DC bus, and the second end of the second resistor is connected to the emitter of the first transistor, the emitter of the second transistor and the negative DC bus.

[0027] In one of the embodiments, the switch circuit includes a field effect transistor;

[0028] The direct current is transmitted via a direct current bus, and the direct current bus comprises a positive direct current bus and a negative direct current bus;

[0029] The gate of the field effect tube serves as the driving signal input terminal of the switching circuit and is connected to the clamping circuit to input the driving signal; the drain of the field effect tube serves as the DC input terminal of the switching circuit and is connected to the negative DC bus to input the DC power; the source of the field effect tube serves as the DC output terminal of the switching circuit and is connected to the negative DC bus to output the DC power.

[0030] In one embodiment, the direct current is transmitted through a direct current bus, and the direct current bus includes a positive direct current bus and a negative direct current bus; the clamping circuit is specifically configured to clamp the load voltage in response to the current sampling signal being greater than a first preset voltage, so as to clamp the current of the direct current output by the switch circuit; wherein the load voltage is used to drive the switch circuit;

[0031] The clamping circuit includes a third transistor, a fifth resistor and a sixth resistor;

[0032] The first end of the fifth resistor serves as the current sampling signal input end of the clamping circuit and is connected to the current sampling circuit to input the current sampling signal; the second end of the fifth resistor is connected to the first end of the sixth resistor and the base of the third transistor, and the collector of the third transistor serves as the load voltage input end of the clamping circuit and the clamped load voltage output end of the clamping circuit and is connected to the switch circuit to access the load voltage and output the clamped load voltage; the second end of the sixth resistor and the emitter of the third transistor are commonly connected to the switch circuit and the negative DC bus.

[0033] An embodiment of the present application further provides an electronic device, which includes the above-mentioned protection circuit.

[0034] Compared with the prior art, the embodiments of the present application have the following beneficial effects: the clamping circuit immediately acts when the current sampling signal is greater than the preset first voltage, no software logic is required to react, the protection speed is fast, and the clamping circuit reduces the possibility of short-term large current during short circuit by clamping the current of the direct current output by the switching circuit, thereby improving the reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical application in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic diagram of a protection circuit provided in one embodiment of the present application;

[0037] Figure 2 Another structural schematic diagram of a protection circuit provided in an embodiment of the present application;

[0038] Figure 3 Another structural schematic diagram of a protection circuit provided in an embodiment of the present application;

[0039] Figure 4 Another structural schematic diagram of a protection circuit provided in an embodiment of the present application;

[0040] Figure 5 A waveform diagram of battery voltage, load current, and load voltage provided in an embodiment of the present application;

[0041] Figure 6 A partial exemplary circuit schematic diagram of a protection circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0044] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and 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 should not be understood as a limitation on the present application.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] Figure 1 The following is a schematic diagram of the structure of a protection circuit provided by an embodiment of the present application. For ease of explanation, only the parts related to the present embodiment are shown, which are described in detail as follows:

[0047] The protection circuit includes a current sampling circuit 100 , a switch circuit 200 and a clamping circuit 300 .

[0048] The current sampling circuit 100 is configured to receive a direct current Id and perform current sampling on the direct current Id to output a current sampling signal Id. ADC .

[0049] The switch circuit 200 is configured to receive a driving signal and transmit a direct current Id according to the driving signal.

[0050] The clamp circuit 300 is connected to the current sampling circuit 100 and the switch circuit 200 and is configured to respond to the current sampling signal I ADC is greater than the first preset voltage, and the current of the direct current Id output by the switch circuit 200 is clamped.

[0051] The first preset voltage can be set according to actual needs. For example, the direct current Id corresponding to the first preset voltage can be set to 10A.

[0052] In a specific implementation, if the current sampling signal I ADC If the voltage is greater than the first preset voltage, it can be considered that a short circuit occurs in the circuit, and the short-circuit current can reach 60A. The clamping circuit 300 clamps the current of the DC power Id output by the switching circuit 200, and can clamp the short-circuit current to 10A within 0.8ms. It has a fast action speed and reduces the short-term impact of the short-circuit current on the system.

[0053] The clamp circuit 300 generates a voltage drop in the current sampling signal I ADC When the voltage is greater than the preset first voltage, it will take action immediately without the need for software logic to react, and the protection speed is fast. In addition, the clamping circuit 300 clamps the current of the direct current Id output by the switching circuit 200, thereby reducing the possibility of short-term large current during a short circuit and improving the reliability of the circuit.

[0054] By way of example and not limitation, Figure 2 As shown, the protection circuit further includes a control circuit 400 and a drive circuit 500 .

[0055] The control circuit 400 is connected to the current sampling circuit 100 and the clamping circuit 300 and is configured to output a control signal.

[0056] The driving circuit 500 is connected to the control circuit 400 , the clamping circuit 300 and the switch circuit 200 , and is configured to output a driving signal according to the control signal.

[0057] The control circuit 400 is further configured to respond to the current sampling signal I ADC If the current sampling signal is greater than the second preset voltage for the first preset time or the current sampling signal is greater than the third preset voltage for the second preset time, the output of the control signal is stopped.

[0058] The signal of the control circuit 400 is amplified by the driving circuit 500 , thereby improving the driving capability of the control circuit 400 .

[0059] It should be noted that when powered on for the first time, the control circuit 400 stops outputting control signals by default, the switch circuit 200 is disconnected, and stops supplying power to the load, thereby reducing the possibility of the load being impacted.

[0060] It should be noted that the first preset voltage, the second preset voltage, the third preset voltage, the first preset time length and the second preset time length can all be set according to actual needs, wherein the first preset voltage is greater than the second preset voltage, the second preset voltage is greater than the third preset voltage, and the first preset time length is less than the second preset time length.

[0061] In a specific implementation, if the current sampling signal I ADC If the current sampling signal I ADC If the voltage is greater than the third preset voltage and less than the second preset voltage for the second preset period of time, it can be considered that the circuit enters an overcurrent state, and the control circuit 400 performs overcurrent protection.

[0062] It can be understood that if the first preset voltage is less than or equal to the second preset voltage, then after the clamping circuit 300 is actuated, the clamped voltage is less than the second preset voltage, and the control circuit 400 will continue to output the control signal, resulting in the inability to completely shut down the load. Therefore, setting the first preset voltage to be greater than the second preset voltage can reduce the risk of the control circuit 400 not completely shutting down the load and improve the safety of the circuit; setting the first preset time length and the second preset time length can reduce the risk of the control circuit 400 misjudgment caused by the power-on impact current spike, thereby reducing the risk of the control circuit 400 malfunctioning.

[0063] For example, when the current sampling signal I ADC is greater than the first preset voltage, that is, the current sampling signal I ADC When the corresponding DC current Id is greater than 10A, the clamping circuit 300 clamps the current of the DC current Id output by the switch circuit 200, and the current sampling signal I corresponding to the clamped DC current Id is ADC is greater than the second preset voltage and less than the first preset voltage; when the current sampling signal I ADC is greater than the second preset voltage and less than the first preset voltage for a second preset time, that is, the current sampling signal I ADC When the corresponding direct current Id is greater than 8A and less than 10A for 5ms, the control circuit 400 stops outputting the control signal to perform short-circuit protection; ADC is greater than the third preset voltage and less than the second preset voltage for a second preset time, that is, the current sampling signal I ADC When the corresponding direct current Id is greater than 6A and less than 8A for 50ms, the control circuit 400 stops outputting the control signal and performs overcurrent protection.

[0064] When the current sampling signal I ADC is greater than the first preset voltage, that is, the current sampling signal I ADC When the corresponding direct current Id is greater than 10A, the clamping circuit 300 clamps the current of the direct current Id output by the switch circuit 200, and performs the first level of short-circuit protection on the circuit; when the current sampling signal I ADC is greater than the second preset voltage for the first preset time, that is, the current sampling signal I ADCWhen the corresponding direct current Id is greater than 8A and less than 10A for 5ms, the control circuit 400 stops outputting the control signal, disconnects the switch circuit 200, and performs a second short-circuit protection on the circuit, thereby improving the protection capability of the circuit.

[0065] If the control circuit 400 is ADC is greater than the second preset voltage for the first preset time or the current sampling signal I ADC The control circuit 400 can be set to make a judgment again after the third preset time. If the current sampling signal I ADC When the voltage is less than the third preset voltage, the control circuit 400 re-outputs the control signal, thereby solving the circuit current fault in a short time and automatically restarting without manual restart, thus saving manual maintenance costs and time. The third preset time can be set according to actual needs, for example, it can be set to 1 minute.

[0066] By way of example and not limitation, Figure 3 As shown, the protection circuit further includes a voltage sampling circuit 600 .

[0067] The voltage sampling circuit 600 is connected to the control circuit 400 and is configured to perform voltage sampling on the direct current Id to output a voltage sampling signal.

[0068] The control circuit 400 is further configured to stop outputting the control signal in response to the voltage sampling signal being less than a fourth preset voltage.

[0069] If the voltage sampling signal is less than the third preset voltage, it can be considered that the circuit has entered an undervoltage abnormal state. It should be noted that when the circuit is working, it is possible to enter an undervoltage abnormal state at any time. Therefore, in the design, the undervoltage abnormal state should be set as the highest priority for the control circuit 400 to respond. If the circuit enters an undervoltage abnormal state, the control circuit 400 needs to immediately stop outputting the control signal to improve the reliability of the circuit.

[0070] The control circuit 400 can also output the control signal again in response to the voltage sampling signal being greater than the fourth preset voltage for a fourth preset time after stopping outputting the control signal in response to the voltage sampling signal being less than the fourth preset voltage, thereby solving the circuit voltage failure in a short time and automatically restarting without manual restart, saving manual maintenance costs and time. The fourth preset time can be set according to actual needs, for example, it can be 10 minutes.

[0071] By way of example and not limitation, Figure 4 As shown, the protection circuit further includes a soft start circuit 700 .

[0072] The soft start circuit 700 is connected to the driving circuit 500 , the clamping circuit 300 and the switching circuit 200 , and is configured to adjust the load voltage of the switching circuit 200 ; wherein the load voltage is used to drive the switching circuit 200 and is slowly increased to a rated voltage value.

[0073] The switch circuit 200 is specifically configured to transmit the direct current Id according to the adjusted driving signal.

[0074] For high current systems, the surge current and voltage drop at the moment of switch-on can cause serious impact. After the control circuit 400 outputs the control signal, the soft start circuit 700 can reduce the surge current at the moment of switch-on, prevent the surge current from lowering the power supply voltage and affecting the operation of other electronic systems, thereby improving the stability and reliability of the circuit.

[0075] Figure 6 A partial exemplary circuit structure of a protection circuit provided by an embodiment of the present application is shown. For the sake of convenience, only the part related to the embodiment of the present application is shown, which is described in detail as follows:

[0076] The direct current Id is transmitted through a direct current bus, which includes a positive direct current bus and a negative direct current bus. The current sampling circuit 100 is connected in series to the positive direct current bus, and the switch circuit 200 is connected in series to the negative direct current bus. The first terminal P+ is connected to the positive pole of the battery and the positive direct current bus, the second terminal P- is connected to the negative pole of the battery and the negative direct current bus, the third terminal LOAD+ is connected to the positive pole of the load and the positive direct current bus, and the fourth terminal LOAD- is connected to the negative pole of the load and the negative direct current bus.

[0077] The soft start circuit 700 includes a ninth resistor R9, a tenth resistor R10 and a first capacitor C1.

[0078] The first end of the ninth resistor R9 serves as a load voltage input terminal of the soft start circuit 700, and is connected to the drive circuit 500 to input the load voltage; the second end of the ninth resistor R9 and the first end of the first capacitor C1 serve together as an adjusted drive signal output terminal OUT of the soft start circuit 700, and are connected to the switch circuit 200 and the clamp circuit 300 to output the adjusted drive signal; the second end of the first capacitor C1 is connected to the first end of the tenth resistor R10, and the second end of the tenth resistor R10 is connected to the negative DC bus.

[0079] The soft start circuit 700 may further include a first diode D1 connected in parallel with the ninth resistor R9.

[0080] like Figure 5 As shown in a in FIG. 1 , if there is no soft start circuit 700, the surge current at power-on will cause the load voltage to drop suddenly, such as Figure 5As shown in b, by coordinating the parameters of the field effect tube M1 in the switch circuit 200 with the parameters of the ninth resistor R9, the tenth resistor R10 and the first capacitor C1, the rising slope of the load voltage can be controlled, the surge current at the moment when the field effect tube M1 is turned on can be reduced, and the field effect tube M1 can be turned on slowly; when the field effect tube M1 is turned off, the voltage between its gate and source can be quickly discharged through the first diode D1, accelerating the turning off of the field effect tube M1.

[0081] The control circuit 400 includes a microprocessor U2.

[0082] The first universal input / output terminal P1.0 of the microprocessor U2 is used as the voltage sampling signal input terminal of the control circuit 400 to input the voltage sampling signal; the second universal input / output terminal P1.1 of the microprocessor U2 is used as the current sampling signal input terminal of the control circuit 400 to connect to the current sampling circuit 100 to input the current sampling signal I ADC The third general input and output terminal P2.0 of the microprocessor U2 serves as the control signal output terminal OUT of the control circuit 400 and is connected to the drive circuit 500 to output a control signal.

[0083] The circuit is simple and reliable.

[0084] The driving circuit 500 includes a first transistor Q1 , a second transistor Q2 , a second resistor R2 , a third resistor R3 , and a fourth resistor R4 .

[0085] The base of the first transistor Q1 and the first end of the second resistor R2 serve together as a control signal input end of the drive circuit 500, and are connected to the control circuit 400 to input a control signal; the collector of the first transistor Q1 is connected to the base of the second transistor Q2 and the first end of the third resistor R3, and the collector of the second transistor Q2 and the first end of the fourth resistor R4 serve together as a drive signal output end OUT of the drive circuit 500, and are connected to the switch circuit 200 to output a drive signal; the second end of the third resistor R3 is connected to the second end of the fourth resistor R4 and the positive DC bus, and the second end of the second resistor R2 is connected to the emitter of the first transistor Q1, the emitter of the second transistor Q2 and the negative DC bus.

[0086] The circuit only uses transistors and resistors, and has a simple circuit and low cost.

[0087] The switch circuit 200 includes a field effect transistor M1 .

[0088] The gate of the field effect transistor M1 serves as a driving signal input terminal of the switch circuit 200, and is connected to the clamp circuit 300 to input a driving signal; the drain of the field effect transistor M1 serves as a DC input terminal of the switch circuit 200, and is connected to the negative DC bus to input DC power Id; the source of the field effect transistor M1 serves as a DC power Id output terminal OUT of the switch circuit 200, and is connected to the negative DC bus to output DC power Id.

[0089] The field effect transistor M1 may be a high-power field effect transistor.

[0090] The field effect tube M1 has a fast response speed, which improves the circuit reaction time.

[0091] The clamping circuit 300 includes a third transistor Q3 , a fifth resistor R5 , and a sixth resistor R6 .

[0092] The DC power is transmitted through the DC bus, which includes a positive DC bus and a negative DC bus; the clamping circuit 300 is specifically configured to clamp the load voltage in response to the current sampling signal being greater than the first preset voltage, so as to clamp the current of the DC power output by the switch circuit 200. The load voltage is used to drive the switch circuit 200.

[0093] The first end of the fifth resistor R5 serves as the current sampling signal input end of the clamping circuit 300, and is connected to the current sampling circuit 100 to input the current sampling signal; the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6 and the base of the third transistor Q3, and the collector of the third transistor Q3 serves as the load voltage input end of the clamping circuit 300 and the clamped load voltage output end of the clamping circuit 300, and is connected to the switch circuit 200 to access the load voltage and output the clamped load voltage; the second end of the sixth resistor R6 and the emitter of the third transistor Q3 are commonly connected to the switch circuit 200 and the negative DC bus.

[0094] In a specific implementation, the amplifier U1 in the current sampling circuit 100 may have an amplification factor of 50, and the current sampling signal I ADC It is obtained by amplifying the voltage drop of the direct current Id on the first resistor R1 by 50 times. Let Vbe be the voltage between the base and the emitter of the third transistor Q3, Ib be the base current of the third transistor Q3, and Vgs be the voltage between the gate and the source of the field effect transistor M1.

[0095] Depend on Figure 6 We can get:

[0096] I ADC =R1*50*Id(1)

[0097] I ADC =Vbe*(R5+R6) / R6+Ib*R5(2)

[0098] From formula (1) and (2), we can get: Vbe = [R1*50*Id-R5*Ib]*R6 / (R5+R6) (3)

[0099] Therefore, Vbe∝Id(4)

[0100] As the DC current Id increases, the circuit goes through the following stages:

[0101] In the first stage, the third transistor Q3 is in the cut-off region, and the field effect transistor M1 is in the variable resistance region. At this time, the base current Ib of the third transistor Q3 is 0.

[0102] In the second stage, the third transistor Q3 is in the amplification area, and the field effect transistor M1 is in the variable resistance area. At this time, according to the input characteristics of the transistor,

[0103] Vbe∝Ib(5)

[0104] According to the output characteristics of the transistor, we can get

[0105] Ic=β*Ib(6)

[0106] Vce∝1 / Ic(7)

[0107] Where Ic is the collector current of the third transistor Q3, β is the current amplification factor of the third transistor Q3, and Vce is the voltage between the collector and emitter of the third transistor Q3. From equations (3)(5)(6)(7), we can get

[0108] Vce∝1 / Ic∝1 / Ib∝1 / Id(8)

[0109] Since Vgs = Vce, we can get

[0110] Vgs∝1 / Id(9).

[0111] In the third stage, the third transistor Q3 is in the amplification area, and the field effect tube M1 is in the constant current area. According to the transfer characteristics of the field effect tube M1, it can be obtained that

[0112] Vgs∝Id(10)

[0113] From equations (9) and (10), we know that there is an intersection between the load characteristic and transfer characteristic curves of Vgs-Id.

[0114] This can be understood as, when the third transistor Q3 works in the amplification area and the field effect tube M1 works in the variable resistance area, according to the field effect tube M1 load working curve, as the load current Id increases, Vgs decreases; this makes the field effect tube M1 enter the constant current area, and after the field effect tube M1 enters the constant current area, the field effect tube M1 transfer characteristics make Vgs increase as Id increases. Under the action of the load working curve and the transfer characteristics, Vgs finally reaches a balance point, which is the final field effect tube M1 working point, thereby realizing the clamping of the field effect tube M1 by the third transistor Q3, and the specific balance point can be obtained by adjusting the parameters of each circuit component according to the actual situation.

[0115] The current sampling circuit 100 includes an amplifier U1 and a first resistor R1.

[0116] The positive input terminal Vin+ of the amplifier U1 is connected to the first end of the first resistor R1 and the positive electrode of the DC bus, and the negative input terminal Vin- of the amplifier U1 is connected to the second end of the first resistor R1 and the positive electrode of the DC bus. The positive input terminal Vin+ of the amplifier U1, the first end of the first resistor R1, the negative input terminal Vin- of the amplifier U1 and the second end of the first resistor R1 serve together as the DC input terminal of the current sampling circuit 100 to input the DC power Id; the output terminal OUT of the amplifier U1 serves as the current sampling signal output terminal OUT of the current sampling circuit 100, and is connected to the control circuit 400 and the clamping circuit 300 to output the current sampling signal Id. ADC .

[0117] It should be noted that the amplifier U1 here may include an operational amplifier.

[0118] The voltage sampling circuit 600 includes a seventh resistor R7, an eighth resistor R8, an eleventh resistor R11 and a second capacitor C2.

[0119] The first end of the seventh resistor R7 serves as the DC input end of the voltage sampling circuit 600 and is connected to the positive pole of the DC bus to access the DC power Id; the second end of the seventh resistor R7 is connected to the first end of the eighth resistor R8 and the first end of the eleventh resistor R11, and the second end of the eleventh resistor R11 and the first end of the second capacitor C2 serve as the voltage sampling signal output end OUT of the voltage sampling circuit 600 and are connected to the control circuit 400 to output the voltage sampling signal; the second end of the eighth resistor R8 and the second end of the second capacitor C2 are commonly connected to the power ground.

[0120] The following is a combination of working principles Figure 6 As shown for further explanation:

[0121] The third general input and output terminal P2.0 of the microprocessor U2 outputs a control signal to the base of the first transistor Q1 and the first end of the second resistor R2, the first transistor Q1 is turned on, the second transistor Q2 is turned off, and a drive signal is output from the collector of the second transistor Q2 and the first end of the fourth resistor R4 to the first end of the ninth resistor R9. The first capacitor C1 stores energy according to the drive signal, so that the voltage at the first end of the first capacitor C1 gradually increases to the rated voltage value, and the adjusted drive signal is output from the second end of the ninth resistor R9 and the first end of the first capacitor C1 to the gate of the field effect transistor M1. The field effect transistor M1 is turned on to transmit direct current Id.

[0122] The first resistor R1 samples the DC current Id, and the amplifier U1 amplifies the sampled voltage and outputs a current sampling signal Id from the output terminal OUT of the amplifier U1. ADC to the second universal input / output terminal P1.1 of the microprocessor U2 and the first terminal of the fifth resistor R5. If the current sampling signal I ADC If the current sampling signal I ADC If the current sampling signal I ADC If the current sampling signal I is greater than the third preset voltage and less than the second preset voltage, the microprocessor U2 stops outputting the control signal after the second preset time, and the field effect tube M1 is turned off. ADC To judge, if the current sampling signal I ADC If the voltage is less than the third preset voltage, the control circuit 400 outputs the control signal again, and the circuit starts working again.

[0123] The seventh resistor R7 and the eighth resistor R8 divide the direct current Id, and output a voltage sampling signal from the second end of the eleventh resistor R11 and the first end of the second capacitor C2 to the first general input and output terminal P1.0 of the microprocessor U2. If the voltage sampling signal is less than the fourth preset voltage, the microprocessor U2 stops outputting the control signal, and the field effect transistor M1 is turned off. After the fourth preset time, the control circuit 400 judges the voltage sampling signal again. If the voltage sampling signal is greater than the fourth preset voltage, the control circuit 400 re-outputs the control signal, and the circuit starts working again.

[0124] An embodiment of the present application further provides an electronic device, which includes the above-mentioned protection circuit.

[0125] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0126] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A protection circuit, characterized in that: include: A current sampling circuit is configured to access direct current and perform current sampling on the direct current to output a current sampling signal; a switch circuit configured to receive a drive signal and transmit the direct current according to the drive signal; The clamping circuit is connected to the current sampling circuit and the switch circuit, and is configured to clamp the current of the direct current output by the switch circuit in response to the current sampling signal being greater than a first preset voltage.

2. The protection circuit according to claim 1, characterized in that: Also includes: a control circuit connected to the current sampling circuit and the clamping circuit and configured to output a control signal; a driving circuit connected to the control circuit, the clamping circuit and the switch circuit, and configured to output a driving signal according to the control signal; The control circuit is further configured to stop outputting the control signal in response to the current sampling signal being greater than the second preset voltage for the first preset time or the current sampling signal being greater than the third preset voltage for the second preset time.

3. The protection circuit according to claim 2, characterized in that: Also includes: A voltage sampling circuit, connected to the control circuit, configured to perform voltage sampling on the direct current to output a voltage sampling signal; The control circuit is further configured to stop outputting the control signal in response to the voltage sampling signal being less than a fourth preset voltage.

4. The protection circuit according to claim 2, characterized in that: Also includes: a soft start circuit connected to the driving circuit, the clamping circuit and the switching circuit, and configured to adjust a load voltage of the switching circuit; wherein the load voltage is used to drive the switching circuit and is slowly increased to a rated voltage value; The switch circuit is specifically configured to transmit the direct current according to the adjusted drive signal.

5. The protection circuit according to claim 4, characterized in that: The soft start circuit includes a ninth resistor, a tenth resistor and a first capacitor; The direct current is transmitted via a direct current bus, the direct current bus comprises a positive direct current bus and a negative direct current bus, and the switch circuit is connected in series to the negative direct current bus; The first end of the ninth resistor serves as a load voltage input end of the soft start circuit, and is connected to the drive circuit to input the load voltage; the second end of the ninth resistor and the first end of the first capacitor serve together as an adjusted drive signal output end of the soft start circuit, and are connected to the switch circuit and the clamp circuit to output the adjusted drive signal; the second end of the first capacitor is connected to the first end of the tenth resistor, and the second end of the tenth resistor is connected to the negative DC bus.

6. The protection circuit according to claim 2, characterized in that: The control circuit includes a microprocessor; The first universal input / output terminal of the microprocessor is used as the voltage sampling signal input terminal of the control circuit to input the voltage sampling signal; the second universal input / output terminal of the microprocessor is used as the current sampling signal input terminal of the control circuit to be connected to the current sampling circuit to input the current sampling signal; The third general input / output terminal of the microprocessor serves as a control signal output terminal of the control circuit and is connected to the drive circuit to output the control signal.

7. The protection circuit according to claim 2, characterized in that: The driving circuit includes a first triode, a second triode, a second resistor, a third resistor and a fourth resistor; The direct current is transmitted via a direct current bus, the direct current bus comprises a positive direct current bus and a negative direct current bus, and the switch circuit is connected in series to the negative direct current bus; The base of the first transistor and the first end of the second resistor are used together as a control signal input end of the driving circuit, and are connected to the control circuit to input the control signal; The collector of the first transistor is connected to the base of the second transistor and the first end of the third resistor; the collector of the second transistor and the first end of the fourth resistor serve together as the drive signal output end of the drive circuit and are connected to the switch circuit to output the drive signal; the second end of the third resistor is connected to the second end of the fourth resistor and the positive DC bus; the second end of the second resistor is connected to the emitter of the first transistor, the emitter of the second transistor and the negative DC bus.

8. The protection circuit according to any one of claims 1 to 7, characterized in that: The switch circuit includes a field effect transistor; The direct current is transmitted via a direct current bus, and the direct current bus comprises a positive direct current bus and a negative direct current bus; The gate of the field effect tube serves as the driving signal input terminal of the switching circuit and is connected to the clamping circuit to input the driving signal; the drain of the field effect tube serves as the DC input terminal of the switching circuit and is connected to the negative DC bus to input the DC power; the source of the field effect tube serves as the DC output terminal of the switching circuit and is connected to the negative DC bus to output the DC power.

9. The protection circuit according to claim 1, characterized in that: The direct current is transmitted through a direct current bus, and the direct current bus includes a positive direct current bus and a negative direct current bus; the clamping circuit is specifically configured to clamp a load voltage in response to the current sampling signal being greater than a first preset voltage, so as to clamp the current of the direct current output by the switch circuit; wherein the load voltage is used to drive the switch circuit; The clamping circuit includes a third transistor, a fifth resistor and a sixth resistor; The first end of the fifth resistor serves as the current sampling signal input end of the clamping circuit and is connected to the current sampling circuit to input the current sampling signal; the second end of the fifth resistor is connected to the first end of the sixth resistor and the base of the third transistor, and the collector of the third transistor serves as the load voltage input end of the clamping circuit and the clamped load voltage output end of the clamping circuit and is connected to the switch circuit to access the load voltage and output the clamped load voltage; the second end of the sixth resistor and the emitter of the third transistor are commonly connected to the switch circuit and the negative DC bus.

10. An electronic device, characterized in that: Comprising the protection circuit as claimed in any one of claims 1 to 9.

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