Overcurrent protection circuit and electronic equipment

Abstract

The utility model belongs to the technical field of power supply circuits, and particularly relates to an overcurrent protection circuit and electronic equipment. The overcurrent protection circuit comprises a gear switching module, a current sampling module and an overcurrent protection module; by setting the preset threshold value, the gear switching module can detect the magnitude of the input voltage, and the overcurrent protection module can change the threshold value of overcurrent protection according to whether the gear switching signal is received or not, so that the overcurrent threshold value is matched with the input voltage, and double-gear overcurrent protection is realized.

Description

Technical Field

[0001] This application belongs to the field of power supply circuit technology, and particularly relates to overcurrent protection circuits and electronic equipment. Background Technology

[0002] Currently, the input voltage range of AC-DC switching power supplies that support voltage standards in multiple countries is 100-240VAC. Due to this extremely wide power range, the current flowing through the components is greater when the input voltage is low, and the temperature of the components is more likely to exceed the limit under the same output power.

[0003] When outputting the same power, the current and temperature stresses of internal components under low-voltage input will far exceed those under high-voltage input. If the overcurrent protection threshold of the power supply remains unchanged, and the high-voltage and low-voltage conditions are not differentiated, it is very easy for the temperature stress of the components to exceed the limit, leading to component damage and thus damage to the power supply. In severe cases, it can also cause serious consequences such as damage to downstream equipment and fire. Utility Model Content

[0004] The purpose of this application is to provide an overcurrent protection circuit and electronic device, which aims to solve the problem that the overcurrent protection threshold of traditional wide voltage range power supplies cannot adapt to wide voltage input.

[0005] A first aspect of this application provides an overcurrent protection circuit for overcurrent protection of a power supply circuit, comprising: a gear shifting module connected to the input terminal of the power supply circuit, the gear shifting module being configured to output a gear shifting signal when the input voltage of the power supply circuit is less than a preset threshold; a current sampling module connected to the output terminal of the power supply circuit, the current sampling module being configured to detect the current at the output terminal of the power supply circuit and output a current sampling signal based on the current at the output terminal of the power supply circuit; and an overcurrent protection module connected to the gear shifting module, the current sampling module, and the power supply circuit, the overcurrent protection module being configured to output an overcurrent protection signal to the power supply circuit based on the current sampling signal and a first overcurrent threshold when the gear shifting signal is not received, and to output an overcurrent protection signal to the power supply circuit based on the current sampling signal and a second overcurrent threshold when the gear shifting signal is received.

[0006] In one embodiment, the gear switching module includes a voltage sampling unit and a comparison unit; the voltage sampling unit is connected to the input terminal of the power supply circuit, and the voltage sampling unit is used to obtain a sampled voltage based on the input voltage of the power supply circuit; the comparison unit is connected to the voltage sampling unit and the overcurrent protection module respectively, and the comparison unit is used to output the gear switching signal according to the sampled voltage and the reference voltage.

[0007] In one embodiment, the comparison unit includes a comparator, a first switch, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a first capacitor. The non-inverting input of the comparator is connected to the voltage sampling unit through the first resistor, the inverting input of the comparator is used to connect to the reference voltage, and the output of the comparator is connected to the non-inverting input of the comparator through the second resistor. The output of the comparator is also connected to the control terminal of the first switch through the third resistor. The first terminal of the first switch is connected to the overcurrent protection module and the first terminal of the fourth resistor, respectively. The second terminal of the first switch is grounded, and the second terminal of the fourth resistor is used to connect to the operating voltage. The two terminals of the fifth resistor are connected to the second terminal of the fourth resistor and the output terminal of the comparator, respectively. The two terminals of the first capacitor are connected to the control terminal of the first switch and the second terminal of the first switch, respectively.

[0008] In one embodiment, the power supply circuit includes a rectifier unit and a voltage conversion unit; the rectifier unit is used to generate input DC power based on input AC power, and the voltage conversion unit is connected to the rectifier unit to convert the input DC power into voltage and generate output current.

[0009] In one embodiment, the voltage sampling unit includes a first voltage divider resistor, a second voltage divider resistor, a first unidirectional conductor, a second unidirectional conductor, a first Zener diode, and a second capacitor; the input terminal of the first unidirectional conductor is connected to the first input terminal of the rectifier unit, the output terminal of the first unidirectional conductor is connected to the first terminal of the first voltage divider resistor, the input terminal of the second unidirectional conductor is connected to the second input terminal of the rectifier unit, and the output terminal of the second unidirectional conductor is connected to the first terminal of the first voltage divider resistor; the second terminal of the first voltage divider resistor is connected to the first terminal of the second voltage divider resistor, the cathode of the first Zener diode, the first terminal of the second capacitor, and the comparator unit, respectively; the second terminal of the second voltage divider resistor, the anode of the first Zener diode, and the second terminal of the second capacitor are grounded.

[0010] In one embodiment, the gear switching module further includes a reference voltage unit, which is connected to the comparison unit and is used to output the reference voltage.

[0011] In one embodiment, the overcurrent protection module includes an operational amplifier unit and an overcurrent protection unit; the operational amplifier unit is configured to output a first amplified signal based on the current sampling signal when the gear shift signal is not received, and to output a second amplified signal based on the current sampling signal and the gear shift signal when the gear shift signal is received; the overcurrent protection unit is configured to output an overcurrent protection signal based on the first amplified signal or the second amplified signal, and the overcurrent protection signal is used to trigger the overcurrent protection of the power supply circuit.

[0012] In one embodiment, the operational amplifier unit includes a first isolation device, an operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a third capacitor; the first isolation device is connected between the positive output terminal of the power supply circuit and the first end of the sixth resistor, and the first isolation device is used to conduct when the gear switching signal is received; the second end of the sixth resistor is connected to the non-inverting input terminal of the operational amplifier and the first end of the seventh resistor, the second end of the seventh resistor is grounded, the inverting input terminal of the operational amplifier is connected to the current sampling module through the eighth resistor, the output terminal of the operational amplifier is connected to the overcurrent protection unit, the output terminal of the operational amplifier is connected to the inverting input terminal of the operational amplifier through the ninth resistor, and the third capacitor is connected in parallel with the ninth resistor.

[0013] In one embodiment, the overcurrent protection unit includes a second Zener diode, a tenth resistor, and a second isolation device; the negative terminal of the second Zener diode is connected to the operational amplifier unit, and the positive terminal of the second Zener diode is connected to the second isolation device through the tenth resistor. The second isolation device is connected between the feedback terminal of the power supply circuit and ground, and the second isolation device is used to conduct when the voltage of the first amplified signal or the second amplified signal is greater than the protection threshold.

[0014] A second aspect of this application provides an electronic device, including a power supply circuit and an overcurrent protection circuit as described above, wherein the overcurrent protection circuit is connected to the power supply circuit and is used to provide overcurrent protection for the power supply circuit.

[0015] The beneficial effects of this application embodiment compared with the prior art are as follows: by setting a preset threshold, the gear switching module can detect the magnitude of the input voltage, and the overcurrent protection module can change the overcurrent protection threshold according to whether a gear switching signal is received, so that the overcurrent threshold matches the input voltage, thereby realizing dual-gear overcurrent protection. Attached Figure Description

[0016] Figure 1 A schematic diagram of an overcurrent protection circuit provided in an embodiment of this application;

[0017] Figure 2 A circuit diagram of a gear shifting module provided in an embodiment of this application;

[0018] Figure 3 A circuit diagram of a current sampling module and an overcurrent protection module provided in an embodiment of this application;

[0019] Figure 4 This is a schematic diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0022] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0024] For power supply circuits controlled by buttons, some circuits can recognize long presses. When the controller malfunctions, a long press can trigger the restart or repair function of the power supply circuit. However, recognizing long presses usually requires a delay circuit, which is greatly affected by temperature. For example, if a power supply circuit designed for normal temperature requires a 5-second press, it may only require 1 second at high temperatures and 10 seconds at low temperatures, severely impacting the reliability of the power supply circuit.

[0025] Figure 1 A schematic diagram of an overcurrent protection circuit according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and the details are as follows:

[0026] An overcurrent protection circuit 10 is provided for overcurrent protection of a power supply circuit 20. The overcurrent protection circuit 10 includes a gear shifting module 100, a current sampling module 200, and an overcurrent protection module 300.

[0027] The gear shifting module 100 is connected to the input terminal of the power supply circuit 20. The gear shifting module 100 outputs a gear shifting signal when the input voltage of the power supply circuit 20 is less than a preset threshold. The current sampling module 200 is connected to the output terminal of the power supply circuit 20. The current sampling module 200 detects the current at the output terminal of the power supply circuit 20 and outputs a current sampling signal based on the current at the output terminal of the power supply circuit 20. The overcurrent protection module 300 is connected to the gear shifting module 100, the current sampling module 200, and the power supply circuit 20. The overcurrent protection module 300 outputs an overcurrent protection signal to the power supply circuit 20 based on the current sampling signal and a first overcurrent threshold when no gear shifting signal is received, and outputs an overcurrent protection signal to the power supply circuit 20 based on the current sampling signal and a second overcurrent threshold when a gear shifting signal is received. The first overcurrent threshold is less than the second overcurrent threshold.

[0028] By setting a preset threshold, the gear switching module 100 can detect the magnitude of the input voltage. The overcurrent protection module 300 can change the overcurrent protection threshold according to whether a gear switching signal is received, so that the overcurrent threshold matches the input voltage, thereby realizing dual-gear overcurrent protection.

[0029] In one embodiment, such as Figure 2 As shown, the gear switching module 100 includes a voltage sampling unit 110 and a comparison unit 120.

[0030] The voltage sampling unit 110 is connected to the input terminal of the power supply circuit 20. The voltage sampling unit 110 is used to obtain the sampled voltage based on the input voltage of the power supply circuit 20. The comparison unit 120 is connected to the voltage sampling unit 110 and the overcurrent protection module 300 respectively. The comparison unit 120 is used to output a range switching signal based on the sampled voltage and the reference voltage.

[0031] Specifically, the voltage sampling unit 110 can divide the input voltage according to a certain ratio to obtain the sampled voltage. The comparison unit 120 can output a range switching signal when the sampled voltage is less than the reference voltage.

[0032] In one embodiment, the comparison unit 120 includes a comparator U4, a first switch Q1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a first capacitor C1.

[0033] The non-inverting input of comparator U4 is connected to the voltage sampling unit 110 through the first resistor R1. The inverting input of comparator U4 is used to connect to the reference voltage. The output of comparator U4 is connected to the non-inverting input of comparator U4 through the second resistor R2. The output of comparator U4 is also connected to the control terminal of the first switch Q1 through the third resistor R3. The first terminal of the first switch Q1 is connected to the overcurrent protection module 300 and the first terminal of the fourth resistor R4 respectively. The second terminal of the first switch Q1 is grounded. The second terminal of the fourth resistor R4 is used to connect to the working voltage Vcc. The two ends of the fifth resistor R5 are connected to the second terminal of the fourth resistor R4 and the output terminal of comparator U4 respectively. The two ends of the first capacitor C1 are connected to the control terminal of the first switch Q1 and the second terminal of the first switch Q1 respectively.

[0034] It should be noted that when the voltage at the non-inverting input terminal (sampling voltage) of comparator U4 is less than the voltage at the inverting input terminal (reference voltage) of comparator U4, comparator U4 can control the first switch Q1 to open, thereby outputting a gear switching signal based on the operating voltage through the fourth resistor R4.

[0035] When the voltage at the non-inverting input terminal (sampling voltage) of comparator U4 is greater than the voltage at the inverting input terminal (reference voltage) of comparator U4, comparator U4 can control the first switch Q1 to turn on, thereby grounding the first terminal of the first switch Q1 and stopping the output of the gear switching signal.

[0036] Specifically, the first switch Q1 may include an NPN transistor or an N-type MOSFET.

[0037] In some embodiments, the comparator unit 120 may also replace the comparator U4 with an operational amplifier.

[0038] In one embodiment, the power supply circuit 20 includes a rectifier unit 21 and a voltage conversion unit 22; the rectifier unit 21 is used to generate input DC power based on input AC power, and the voltage conversion unit 22 is connected to the rectifier unit 21 and is used to convert the input DC power into voltage to generate output current.

[0039] AC / DC conversion can be achieved through rectifier unit 21 and voltage conversion unit 22.

[0040] In some embodiments, the power supply circuit 20 may also be a DC / DC conversion circuit. This embodiment does not limit the specific type of the power supply circuit 20.

[0041] In one embodiment, the voltage sampling unit 110 includes a first voltage divider resistor R13, a second voltage divider resistor R14, a first unidirectional conductor D1, a second unidirectional conductor D2, a first Zener diode ZD1, and a second capacitor C2.

[0042] The input terminal of the first unidirectional conductor D1 is connected to the first input terminal of the rectifier unit 21, and the output terminal of the first unidirectional conductor D1 is connected to the first terminal of the first voltage divider resistor R13. The input terminal of the second unidirectional conductor D2 is connected to the second input terminal of the rectifier unit 21, and the output terminal of the second unidirectional conductor D2 is connected to the first terminal of the first voltage divider resistor R13. The second terminal of the first voltage divider resistor R13 is connected to the first terminal of the second voltage divider resistor R14, the negative terminal of the first Zener diode ZD1, the first terminal of the second capacitor C2, and the comparator unit 120. The second terminal of the second voltage divider resistor R14, the positive terminal of the first Zener diode ZD1, and the second terminal of the second capacitor C2 are grounded.

[0043] Both the first unidirectional conductor D1 and the second unidirectional conductor D2 can include diodes.

[0044] In the case that the power supply circuit 20 is an AC / DC conversion circuit, since the input voltage is AC, two unidirectional conductors are required to be connected to the two input terminals respectively, and the two unidirectional conductors are turned on in turn.

[0045] By configuring the ratio of the resistance of the first voltage divider resistor R13 and the second voltage divider resistor R14, the input voltage can be divided according to a certain ratio to obtain the sampling voltage.

[0046] The second capacitor C2 can filter the sampling voltage to improve its stability, while the first Zener diode ZD1 can limit the sampling voltage to prevent the gear switching module 100 from being subjected to voltage surges when the input AC power connected to the power circuit 20 fluctuates abnormally or when struck by lightning.

[0047] In one embodiment, such as Figure 2 As shown, the gear shifting module 100 also includes a reference voltage unit 130, which is connected to the comparison unit 120 and is used to output a reference voltage.

[0048] It is understandable that the magnitude of the reference voltage corresponds to the preset threshold. The larger the reference voltage, the larger the preset threshold. The reference voltage can be set according to actual needs. Specifically, it needs to be set according to the preset threshold, the actual input voltage, and the voltage division ratio of the voltage sampling unit 110.

[0049] In some embodiments, the reference voltage can be set to 2.5V.

[0050] In one embodiment, such as Figure 3 As shown, the overcurrent protection module 300 includes an operational amplifier unit 310 and an overcurrent protection unit 320. The operational amplifier unit 310 is used to output a first amplified signal based on the current sampling signal when no gear shift signal is received, and to output a second amplified signal based on the current sampling signal and the gear shift signal when a gear shift signal is received. The overcurrent protection unit 320 is used to trigger the overcurrent protection of the power supply circuit 20 when the first amplified signal or the second amplified signal is greater than the protection threshold.

[0051] It is understandable that the operational amplifier unit 310 can select to output either the first amplified signal or the second amplified signal depending on whether a gear shift signal is received.

[0052] When the operational amplifier unit 310 outputs the first amplified signal, the overcurrent threshold corresponding to the overcurrent protection module 300 is the first overcurrent threshold. When the operational amplifier unit 310 outputs the second amplified signal, the overcurrent threshold corresponding to the overcurrent protection module 300 is the second overcurrent threshold.

[0053] In one embodiment, such as Figure 3 As shown, the operational amplifier unit 310 includes a first isolation device U2, an operational amplifier U1, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a third capacitor C3. The first isolation device U2 is connected between the positive output terminal of the power supply circuit 20 and the first end of the sixth resistor R6. The first isolation device U2 is used to conduct when a gear switching signal is received. The second end of the sixth resistor R6 is connected to the non-inverting input terminal of the operational amplifier U1 and the first end of the seventh resistor R7, respectively. The second end of the seventh resistor R7 is grounded. The inverting input terminal of the operational amplifier U1 is connected to the current sampling module 200 through the eighth resistor R8. The output terminal of the operational amplifier U1 is connected to the overcurrent protection unit 320. The output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U1 through the ninth resistor R9. The third capacitor C3 is connected in parallel with the ninth resistor R9.

[0054] The first isolation device U2 may include an optocoupler. Specifically, the first terminal of the light-emitting diode of the first isolation device U2 can be connected to the gear shifting module 100 (the first terminal of the first switch Q1) to receive the gear shifting signal. The second terminal of the light-emitting diode of the first isolation device U2 can be grounded. The first terminal of the phototransistor of the first isolation device U2 can be connected to the positive output of the power supply circuit 20. The second terminal of the phototransistor of the first isolation device U2 can be connected to the first terminal of the sixth resistor R6.

[0055] The gear shift signal can be used to control the on and off of the first isolation device U2, and adjust the voltage at the non-inverting input terminal of the operational amplifier U1. When the voltage at the non-inverting input terminal of the operational amplifier U1 changes, the output of the operational amplifier U1 will also change accordingly.

[0056] Specifically, when the first isolation device U2 is turned off, the voltage at the non-inverting input terminal of the operational amplifier U1 is 0V, and the operational amplifier U1 can generate a first amplified signal based on the current sampling signal received at the inverting input terminal and the 0V at the non-inverting input terminal.

[0057] When the first isolation device U2 is turned on, the output voltage divider is provided to the non-inverting input terminal of the operational amplifier U1 through the sixth resistor R6 and the seventh resistor R7. The operational amplifier U1 can generate a second amplified signal based on the current sampling signal received at the inverting input terminal and the output voltage divider at the non-inverting input terminal.

[0058] It is understandable that when the output current is equal, the first amplified signal is less than the second amplified signal. At the same time, if overcurrent protection needs to be triggered while the protection threshold remains unchanged, the output current corresponding to the first amplified signal is greater than the output current corresponding to the second amplified signal. That is, the first overcurrent threshold corresponding to the first amplified signal is less than the second overcurrent threshold corresponding to the second amplified signal, thereby realizing the gear switching. In other words, for the current sampling signal, the threshold used for comparison switches between the first overcurrent threshold and the second overcurrent threshold.

[0059] In one embodiment, such as Figure 3 As shown, the overcurrent protection unit 320 includes a second Zener diode ZD2, a tenth resistor R10, and a second isolation device U3. The cathode of the second Zener diode ZD2 is connected to the operational amplifier unit 310, and the anode of the second Zener diode ZD2 is connected to the second isolation device U3 through the tenth resistor R10. The second isolation device U3 is connected between the feedback terminal FB of the power supply circuit 20 and ground. The second isolation device U3 is used to turn on when the voltage of the first amplified signal or the second amplified signal is greater than the protection threshold.

[0060] The second isolation device U3 can be an optocoupler. Specifically, the first terminal of the light-emitting diode of the second isolation device U3 can be connected to the tenth resistor R10, the second terminal of the light-emitting diode of the second isolation device U3 can be grounded, the first terminal of the phototransistor of the second isolation device U3 can be connected to the feedback terminal FB of the power supply circuit 20, and the second terminal of the phototransistor of the second isolation device U3 can be grounded.

[0061] Understandably, when the voltage of the first or second amplified signal exceeds the protection threshold, the second Zener diode ZD2 conducts, thereby controlling the second isolation device U3 to conduct. The overcurrent protection signal is a low-level signal. When the second isolation device U3 conducts, the feedback terminal of the power supply circuit 20 is grounded, thereby triggering the overcurrent protection of the power supply circuit 20.

[0062] In some embodiments, the power supply circuit 20 will shut down after triggering overcurrent protection.

[0063] In one embodiment, such as Figure 3 As shown, the current sampling module 200 includes a sampling resistor R11 and a limiting diode D3. The first terminal of the sampling resistor R11 is connected to the negative output terminal of the power supply circuit 20, and the second terminal of the sampling resistor R11 is connected to the load and grounded. The positive terminal of the limiting diode D3 is connected to the second terminal of the sampling resistor R11, and the negative terminal of the limiting diode D3 is connected to the first terminal of the sampling resistor R11.

[0064] When the power supply circuit 20 outputs, a current I is generated across the sampling resistor R11. out proportional voltage drop V CS Since the reference ground GND is at the second terminal of the sampling resistor R11, the current flows from the second terminal of the sampling resistor R11 to the first terminal of the sampling resistor R11, therefore the output current I... out If V is negative, CS It is also a negative value, voltage drop V CS The calculation formula is:

[0065] V CS =-I out *R11 (1)

[0066] The limiting diode D3 is used to limit the voltage drop across the sampling resistor R11 to prevent the sampling resistor R11 from being subjected to a large current surge during insertion and removal.

[0067] Based on such Figure 2 The gear shifting module 100 shown is based on the input voltage V. AC Sampling voltage V in The calculation formula is:

[0068]

[0069] It should be noted that, Figure 2 In the above, the comparator composed of comparator U4 is a hysteresis comparator, which can effectively avoid input voltage V AC The fluctuations in voltage cause instability in the output of comparator U4. The hysteresis comparator is based on a 2.5V reference voltage and an operating voltage V. CC The first comparison voltage V obtained in1Second comparison voltage V in2 The calculation formula is:

[0070]

[0071]

[0072] Therefore, when the sampling voltage V in Gradually increase and the sampling voltage V in Less than or equal to the first comparison voltage V in1 When the sampled voltage V is low, comparator U4 outputs a low level, controlling the first switch Q1 to turn off. in Gradually increase and the sampling voltage V in Greater than the first comparison voltage V in1 When the comparator U4 outputs a high level (gear switching signal), it controls the first switch Q1 to turn on.

[0073] When the sampling voltage V in Gradually decrease and the sampling voltage V in Greater than or equal to the second comparison voltage V in2 When the comparator U4 outputs a high level (gear shift signal), it controls the first switch Q1 to turn on. When the sampled voltage V... in Gradually decrease and the sampling voltage V in Less than the second comparison voltage V in2 When the comparator U4 outputs a low level, it controls the first switch Q1 to turn off.

[0074] Accordingly, the preset thresholds include a first preset threshold V. AC1 Second preset threshold V AC2 According to equations (2), (3), and (4), the first preset threshold V can be obtained. AC1 Second preset threshold V AC2 The calculation formula is as follows:

[0075]

[0076] Correspondingly, when the input voltage V AC Gradually increase and input voltage V AC Less than or equal to the first preset threshold V AC1 When the input voltage V is low, comparator U4 outputs a low level, controlling the first switch Q1 to turn off. AC Gradually increase and input voltage V AC Greater than the first preset threshold V AC1 When the comparator U4 outputs a high level (gear switching signal), it controls the first switch Q1 to turn on.

[0077] When the input voltage V AC Gradually decrease and input voltage V ACGreater than or equal to the second preset threshold V AC2 When the input voltage V is high, comparator U4 outputs a high level (gear shift signal), controlling the first switch Q1 to turn on. AC Gradually decrease and input voltage V AC Less than the second preset threshold V AC2 When the comparator U4 outputs a low level, it controls the first switch Q1 to turn off.

[0078] Based on such Figure 3 The overcurrent protection module 300 shown and such Figure 3 The current sampling module 200 shown, when it does not receive a gear shift signal, causing the first isolation device U2 to turn off, the voltage V at the output terminal of the operational amplifier U1 is... O1 The formula for calculating (the first amplified signal) is:

[0079]

[0080] In the formula, I out This is the output current.

[0081] When a gear shift signal is received, causing the first isolation device U2 to conduct, the voltage V at the output of operational amplifier U1... O2 The formula for calculating (the second amplified signal) is:

[0082]

[0083] In the formula, V out+ This is the voltage at the positive output terminal of the power supply circuit 20.

[0084] Correspondingly, the breakdown voltage of the second Zener diode ZD2 is V. Z In this case, the first overcurrent threshold I corresponding to the first amplified signal can be obtained according to the above equations (1), (7), and (8). out.ocp.ll And the second overcurrent threshold I corresponding to the second amplified signal out.ocp.hl The calculation formula is as follows:

[0085]

[0086] It is understandable that the gear shifting module 100 adjusts the input voltage V based on the gear shifting module 100. AC Selecting whether to output a gear shift signal, thereby controlling the overcurrent protection module 300 according to the first overcurrent threshold I. out.ocp.ll Or the second overcurrent threshold I out.ocp.hl For output current I out The system will detect when the output current exceeds the first overcurrent threshold I. out.ocp.ll Or the second overcurrent threshold I out.ocp.hlAt this time, the second Zener diode ZD2 breaks down, thereby turning on the second isolation device U3, so that the feedback terminal FB of the power supply circuit 20 is grounded (sending an overcurrent protection signal).

[0087] Figure 4 A schematic diagram of an electronic device according to an embodiment of this application is shown. For ease of explanation, only the parts related to this embodiment are shown, and the details are as follows:

[0088] An electronic device 30 includes a power supply circuit 20 and an overcurrent protection circuit 10 as described in any of the above embodiments. The overcurrent protection circuit 10 is connected to the power supply circuit 20 and is used to provide overcurrent protection for the power supply circuit 20. The electronic device 30 can be either a power supply device or an electrical device, and this embodiment does not limit it.

[0089] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An overcurrent protection circuit for providing overcurrent protection to a power supply circuit, characterized in that, The overcurrent protection circuit includes: A gear shifting module is connected to the input terminal of the power supply circuit. The gear shifting module is used to output a gear shifting signal when the input voltage of the power supply circuit is less than a preset threshold. A current sampling module is connected to the output terminal of the power supply circuit. The current sampling module is used to detect the current at the output terminal of the power supply circuit and output a current sampling signal based on the current at the output terminal of the power supply circuit. An overcurrent protection module is connected to the gear shifting module, the current sampling module, and the power supply circuit. The overcurrent protection module is used to output an overcurrent protection signal to the power supply circuit based on the current sampling signal and a first overcurrent threshold when the gear shifting signal is not received, and to output an overcurrent protection signal to the power supply circuit based on the current sampling signal and a second overcurrent threshold when the gear shifting signal is received, wherein the first overcurrent threshold is less than the second overcurrent threshold.

2. The overcurrent protection circuit as described in claim 1, characterized in that, The gear switching module includes a voltage sampling unit and a comparison unit; The voltage sampling unit is connected to the input terminal of the power supply circuit, and the voltage sampling unit is used to obtain the sampling voltage based on the input voltage of the power supply circuit; The comparison unit is connected to the voltage sampling unit and the overcurrent protection module respectively. The comparison unit is used to output the gear switching signal according to the sampled voltage and the reference voltage.

3. The overcurrent protection circuit as described in claim 2, characterized in that, The comparison unit includes a comparator, a first switch, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a first capacitor; The non-inverting input of the comparator is connected to the voltage sampling unit through the first resistor, the inverting input of the comparator is used to connect to the reference voltage, and the output of the comparator is connected to the non-inverting input of the comparator through the second resistor. The output of the comparator is also connected to the control terminal of the first switch through a third resistor. The first terminal of the first switch is connected to the overcurrent protection module and the first terminal of the fourth resistor. The second terminal of the first switch is grounded. The second terminal of the fourth resistor is used to connect to the working voltage. The two ends of the fifth resistor are connected to the second terminal of the fourth resistor and the output terminal of the comparator, respectively. The two ends of the first capacitor are connected to the control terminal of the first switch and the second terminal of the first switch, respectively.

4. The overcurrent protection circuit as described in claim 2, characterized in that, The power supply circuit includes a rectifier unit and a voltage conversion unit; The rectifier unit is used to generate input DC power based on input AC power. The voltage conversion unit is connected to the rectifier unit and is used to convert the input DC power into voltage to generate output current.

5. The overcurrent protection circuit as described in claim 4, characterized in that, The voltage sampling unit includes a first voltage divider resistor, a second voltage divider resistor, a first unidirectional conductor, a second unidirectional conductor, a first Zener diode, and a second capacitor; The input terminal of the first unidirectional conductor is connected to the first input terminal of the rectifier unit, the output terminal of the first unidirectional conductor is connected to the first terminal of the first voltage divider resistor, the input terminal of the second unidirectional conductor is connected to the second input terminal of the rectifier unit, and the output terminal of the second unidirectional conductor is connected to the first terminal of the first voltage divider resistor. The second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, the negative terminal of the first Zener diode, the first end of the second capacitor, and the comparator unit, respectively. The second end of the second voltage divider resistor, the positive terminal of the first Zener diode, and the second end of the second capacitor are grounded.

6. The overcurrent protection circuit as described in claim 2, characterized in that, The gear shifting module further includes a reference voltage unit, which is connected to the comparison unit and is used to output the reference voltage.

7. The overcurrent protection circuit as described in any one of claims 1 to 6, characterized in that, The overcurrent protection module includes an operational amplifier unit and an overcurrent protection unit; The operational amplifier unit is configured to output a first amplified signal based on the current sampling signal when the gear shift signal is not received, and to output a second amplified signal based on the current sampling signal and the gear shift signal when the gear shift signal is received. The overcurrent protection unit is used to output the overcurrent protection signal when the first amplified signal or the second amplified signal is greater than the protection threshold. The overcurrent protection signal is used to trigger the overcurrent protection of the power supply circuit.

8. The overcurrent protection circuit as described in claim 7, characterized in that, The operational amplifier unit includes a first isolation device, an operational amplifier, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and a third capacitor; The first isolation device is connected between the positive output terminal of the power supply circuit and the first end of the sixth resistor. The first isolation device is used to turn on when the gear switching signal is received. The second end of the sixth resistor is connected to the non-inverting input of the operational amplifier and the first end of the seventh resistor, respectively. The second end of the seventh resistor is grounded. The inverting input of the operational amplifier is connected to the current sampling module through the eighth resistor. The output of the operational amplifier is connected to the overcurrent protection unit. The output of the operational amplifier is connected to the inverting input of the operational amplifier through the ninth resistor. The third capacitor is connected in parallel with the ninth resistor.

9. The overcurrent protection circuit as described in claim 7, characterized in that, The overcurrent protection unit includes a second Zener diode, a tenth resistor, and a second isolation device; The negative terminal of the second Zener diode is connected to the operational amplifier unit, and the positive terminal of the second Zener diode is connected to the second isolation device through the tenth resistor. The second isolation device is connected between the feedback terminal of the power supply circuit and ground. The second isolation device is used to conduct when the voltage of the first amplified signal or the second amplified signal is greater than the protection threshold.

10. An electronic device, characterized in that, It includes a power supply circuit and an overcurrent protection circuit as described in any one of claims 1 to 9, wherein the overcurrent protection circuit is connected to the power supply circuit and is used to provide overcurrent protection for the power supply circuit.

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