Overcurrent protection circuit of switching tube and electronic equipment

Abstract

The utility model discloses an over-current protection circuit of a switching tube and electronic equipment. The over-current protection circuit comprises a sampling resistor and a comparison circuit, the sampling resistor is electrically connected between the output end of the switching tube and the reference ground; the comparison circuit comprises a comparator module and a conversion module connected with the sampling resistor; the conversion module is used for converting a current signal flowing through the sampling resistor into a voltage signal; the comparator module is connected between the conversion module and the controller, and the comparator module is used for comparing the voltage signal with a preset voltage range and sending a preset level signal to the controller when the voltage signal is not in the preset voltage range; and the controller is used for controlling the switching tube to be switched off when receiving the preset level signal. And a proportional amplification circuit is omitted between the sampling resistor and the comparison circuit, so that the response speed of the protection circuit is accelerated, and the protection effectiveness is improved.

Description

Technical Field

[0001] The present application relates to the field of electricity, and more specifically to an overcurrent protection circuit for a switch tube and an electronic device. Background Art

[0002] With the increasing development of electronic equipment products, various types of electronic devices have emerged, such as but not limited to smart phones, tablet computers, car terminals, laptops, smart wearable devices, etc. A large number of switching tubes are used in electronic devices, and the switching tubes can be various types of switching tubes such as but not limited to MOS tubes and triodes. In order to prevent the switch tube from being damaged due to overcurrent, an overcurrent protection circuit is usually provided. The overcurrent protection circuit in the related art needs to use a proportional amplifier circuit, which results in a large response delay of the overcurrent protection circuit, affecting the effectiveness of the protection. Utility Model Content

[0003] The utility model is proposed to solve at least one of the above problems. According to the first aspect of the present application, an overcurrent protection circuit of a switch tube is provided, the overcurrent protection circuit comprising: a sampling resistor and a comparison circuit; wherein the sampling resistor is electrically connected between the output end of the switch tube and a reference ground; the comparison circuit comprises a comparator module and a conversion module connected to the sampling resistor; the conversion module is used to convert a current signal flowing through the sampling resistor into a voltage signal; the comparator module is connected between the conversion module and a controller, the comparator module is used to compare the voltage signal with a preset voltage range, and when the voltage signal is not within the preset voltage range, sends a preset level signal to the controller; the controller is used to control the switch tube to be turned off when receiving the preset level signal.

[0004] In one embodiment of the present application, the comparison circuit includes: a first comparison branch and a second comparison branch; the preset voltage range includes a first voltage threshold and a second voltage threshold; wherein the first comparison branch is used to convert the current signal flowing through the sampling resistor into a first voltage signal, compare the first voltage signal with the first voltage threshold, and when the first voltage signal is greater than the first voltage threshold, send the preset level signal to the controller; the second comparison branch is used to convert the current signal flowing through the sampling resistor into a second voltage signal, compare the second voltage signal with the second voltage threshold, and when the second voltage signal is less than the second voltage threshold, send the preset level signal to the controller.

[0005] In one embodiment of the present application, the current flow direction from the switching tube to the reference ground is a first flow direction, and the current flow direction from the reference ground to the switching tube is a second flow direction; the maximum allowable current value of the first flow direction is a first current threshold, and the maximum allowable current value of the second flow direction is a second current threshold; wherein, the first voltage threshold is determined based on the first current threshold, and the second voltage threshold is determined based on the second current threshold.

[0006] In one embodiment of the present application, the first comparison branch includes: a first comparator module, the first comparator module having a first input terminal, a second input terminal and a first output terminal; wherein the first input terminal is used to input a first reference voltage signal whose voltage value is the first voltage threshold; the second input terminal is used to input the first voltage signal; the first output terminal is electrically connected to the controller, and is used to output the preset level signal to the controller when the first voltage signal is greater than the first reference voltage signal.

[0007] In one embodiment of the present application, the first comparison branch also includes: a first reference voltage branch, electrically connected between the voltage input terminal and the first input terminal, for dividing the reference voltage output from the voltage input terminal into the first reference voltage signal, and inputting the first reference voltage signal into the first input terminal.

[0008] In one embodiment of the present application, the first reference voltage branch includes: a first resistor, and a first reference resistor and a second reference resistor connected in series through a first node; wherein the two ends of the first reference resistor are electrically connected to the positive electrode of the voltage input terminal and the first node, respectively, and the two ends of the second reference resistor are electrically connected to the negative electrode of the voltage input terminal and the first node, respectively; the first resistor is electrically connected between the first node and the first input terminal.

[0009] In one embodiment of the present application, the first comparison branch also includes: a first conversion module, electrically connected between the first end of the sampling resistor, the positive electrode of the voltage input end, and the second input end, for converting the current signal flowing through the sampling resistor into the first voltage signal, and inputting the first voltage signal into the second input end; wherein the second end of the sampling resistor is electrically connected to the reference ground.

[0010] In one embodiment of the present application, the first conversion module includes: a second resistor, and a first voltage-dividing resistor and a second voltage-dividing resistor connected in series through a second node; wherein the two ends of the first voltage-dividing resistor are electrically connected to the first end of the sampling resistor and the second node, respectively; the two ends of the second voltage-dividing resistor are electrically connected to the second node and the positive electrode of the voltage input terminal, respectively; and the second resistor is electrically connected between the second node and the second input terminal.

[0011] In one embodiment of the present application, the second comparison branch includes: a second comparator module, the second comparator module having a third input terminal, a fourth input terminal and a second output terminal; wherein the third input terminal is used to input a second reference voltage signal whose voltage value is the second voltage threshold; the fourth input terminal is used to input the second voltage signal; the second output terminal is electrically connected to the controller, and is used to output the preset level signal to the controller when the second voltage signal is less than the second reference voltage signal.

[0012] In one embodiment of the present application, the second comparison branch also includes: a second reference voltage branch, electrically connected between the voltage input terminal and the third input terminal, for dividing the reference voltage output from the voltage input terminal into the second reference voltage signal, and inputting the second reference voltage signal into the third input terminal.

[0013] In one embodiment of the present application, the second reference voltage branch includes: a third resistor, and a third reference resistor and a fourth reference resistor connected in series through a third node; wherein two ends of the third reference resistor are electrically connected to the positive electrode of the voltage input terminal and the third node, respectively, and two ends of the fourth reference resistor are electrically connected to the negative electrode of the voltage input terminal and the third node, respectively; and the third resistor is electrically connected between the third node and the fourth input terminal.

[0014] In one embodiment of the present application, the second comparison branch also includes: a second conversion module, electrically connected between the first end of the sampling resistor, the positive electrode of the voltage input end, and the fourth input end, for converting the current signal flowing through the sampling resistor into the second voltage signal, and inputting the second voltage signal into the fourth input end; wherein the second end of the sampling resistor is electrically connected to the reference ground.

[0015] In one embodiment of the present application, the second conversion module includes: a fourth resistor, and a third voltage-dividing resistor and a fourth voltage-dividing resistor connected in series through a fourth node; wherein the two ends of the third voltage-dividing resistor are electrically connected to the first end of the sampling resistor and the fourth node, respectively; the two ends of the fourth voltage-dividing resistor are electrically connected to the fourth node and the positive electrode of the voltage input terminal, respectively; and the fourth current-limiting resistor is electrically connected between the fourth node and the fourth input terminal.

[0016] According to the second aspect of the present application, an electronic device is also provided, comprising: a switch tube, a controller and an overcurrent protection circuit of any one of the above switch tubes; wherein the controller is used to control the switch tube to be turned off when receiving the preset level signal.

[0017] According to the overcurrent protection circuit and electronic device of the switch tube provided by the embodiment of the present application, by directly connecting the sampling resistor to the comparison circuit, the conversion module is used to convert the current signal flowing through the sampling resistor into a voltage signal, and the comparator module is used to compare the voltage signal with the preset voltage range, and when the voltage signal is not within the preset voltage range, a preset level signal is sent to the controller, so that the controller controls the switch tube to turn off, and the circuit protection is realized when the switch tube is overcurrent. Compared with the prior art, the proportional amplifier circuit is omitted between the sampling resistor and the comparison circuit, which speeds up the response speed of the protection circuit and improves the effectiveness of the protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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 utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A circuit diagram of an overcurrent protection circuit for a switch tube provided in one embodiment of the utility model;

[0020] Figure 2 A circuit diagram of an overcurrent protection circuit for a switch tube provided by another embodiment of the utility model;

[0021] Figure 3 A circuit diagram of an overcurrent protection circuit for a switch tube provided in another embodiment of the utility model. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the utility model more obvious, the exemplary embodiments according to the utility model will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments of the utility model, and it should be understood that the utility model is not limited to the exemplary embodiments described here. Based on the embodiments of the utility model described in the utility model, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the utility model.

[0023] In the following description, a large number of specific details are given to provide a more thorough understanding of the utility model. However, it is obvious to those skilled in the art that the utility model can be implemented without one or more of these details. In other examples, in order to avoid confusion with the utility model, some technical features known in the art are not described.

[0024] It should be understood that the utility model can be implemented in different forms and should not be interpreted as being limited to the embodiments proposed herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the utility model to those skilled in the art.

[0025] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0026] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0027] The present application embodiment provides an overcurrent protection circuit for a switch tube, referring to Figure 1 The overcurrent protection circuit includes: a sampling resistor and a comparison circuit; wherein the sampling resistor is electrically connected between the output end of the switch tube and the reference ground (such as Figure 1 The GND in it represents the reference ground); the comparison circuit includes a comparator module and a conversion module connected to the sampling resistor; the conversion module is used to convert the current signal flowing through the sampling resistor into a voltage signal; the comparator module is connected between the conversion module and the controller, the comparator module is used to compare the voltage signal with a preset voltage range, and when the voltage signal is not within the preset voltage range, sends a preset level signal to the controller; the controller is used to control the switch tube to be turned off when receiving the preset level signal.

[0028] In the above scheme, by directly connecting the sampling resistor to the comparison circuit, the conversion module is used to convert the current signal flowing through the sampling resistor into a voltage signal, and the comparator module is used to compare the voltage signal with the preset voltage range, and when the voltage signal is not within the preset voltage range, a preset level signal is sent to the controller, so that the controller controls the switch tube to turn off, thereby realizing circuit protection when the switch tube is overcurrent. Compared with the prior art, the proportional amplification circuit is omitted between the sampling resistor and the comparison circuit, which speeds up the response speed of the protection circuit and improves the effectiveness of the protection. The above structures are described in detail below in conjunction with the accompanying drawings.

[0029] refer to Figure 1 The switch tube can be a switch tube in the bridge arm circuit. The switch tube has an input end, an output end, and a control end, wherein the control end is used to control the conduction of the input end and the output end. Figure 1 The control end of the switch tube is used to connect to the controller to receive the control signal of the controller, so that the controller controls the switch tube to be turned off or on, thereby realizing the control of the disconnection or conduction of the input and output ends of the switch tube. Exemplarily, the controller can be a PWM controller to send a control signal of a PWM waveform. Of course, in other embodiments, the controller can also choose to use a single-chip microcomputer. Reference Figure 1 , a sampling resistor is provided in the overcurrent protection circuit, and the sampling resistor is connected between the output end of the switch tube and the reference ground, so as to sample the current flowing through the switch tube. It should be noted here that the sampling resistor is not limited to Figure 1 to Figure 3 In addition, the sampling resistor may also be a sampling resistor device formed by at least two sampling resistors connected in series or in parallel.

[0030] For example, Figure 1 As shown, the switch tube shown in the embodiment of the utility model is a switch tube at the lower bridge arm in the bridge arm circuit. That is, the sampling resistor is electrically connected between the output end of the switch tube at the lower bridge arm of the bridge arm circuit and the reference ground. The type of the switch tube can be, for example, but not limited to, a MOS tube, a triode, etc. The MOS tube can be an N-type MOS tube and a P-type MOS tube, and the triode can be an NPN-type triode or a PNP-type triode.

[0031] Exemplary, reference Figure 1The comparison circuit is electrically connected between the controller and the sampling resistor. The comparison circuit is used to convert the current signal flowing through the sampling resistor into a voltage signal. The comparison circuit is also used to compare the voltage signal with a preset voltage range. The preset voltage range is determined based on the maximum allowable current range between the switch tube and the reference ground. The comparison circuit is also used to send a preset level signal to the controller when the voltage signal is not within the preset voltage range. The controller is used to control the switch tube to turn off when receiving the preset level signal. The preset level signal can be a high level signal or a low level signal. For example, the reference Figure 2 In the scheme shown, the preset level signal is a high level signal. Figure 3 In the scheme shown, the preset level signal is a low level signal. By directly connecting the sampling resistor to the comparison circuit, the comparison circuit is used to convert the current signal flowing through the sampling resistor into a voltage signal, compare the voltage signal with the preset voltage range, and send a preset level signal to the controller when the voltage signal is not within the preset voltage range, so that the controller controls the switch tube to turn off, and realizes circuit protection when the switch tube is overcurrent. Compared with the prior art, the proportional amplifier circuit is omitted between the sampling resistor and the comparison circuit, which speeds up the response speed of the protection circuit and improves the effectiveness of the protection.

[0032] Exemplary, reference Figure 1 The overcurrent protection circuit may also include: a voltage input terminal, a sampling resistor electrically connected between the positive electrode of the voltage input terminal and the reference ground, so that the current flowing through the sampling resistor not only has the current between the output terminal of the switch tube and the reference ground, but also has the current between the voltage input terminal and the reference ground, thereby adjusting the current flowing through the sampling resistor to a certain extent. Figure 1 As shown, the negative electrode of the voltage input terminal is connected to the reference ground, where the reference ground can be a non-isolated reference ground connected to the sampling resistor. Exemplarily, the voltage input terminal can be connected to a reference voltage source for inputting a reference voltage.

[0033] When setting the comparison circuit, various methods may be used, and several methods are exemplarily introduced below.

[0034] When converting the current signal flowing through the sampling resistor into a voltage signal, a variety of methods that do not use differential amplifier circuits and current transformers can be used. Exemplarily, a conversion module can be used to convert the current signal flowing through the sampling resistor into a voltage signal, that is, the conversion module is electrically connected to the sampling resistor, and is used to convert the current signal flowing through the sampling resistor into a voltage signal. Exemplarily, the conversion module can be a voltage grouping branch, and the current signal flowing through the sampling resistor is converted into a voltage signal through a voltage divider resistor connected to the sampling resistor. When comparing the voltage signal with a preset voltage range, a variety of methods can be used. Exemplarily, a comparator module can be used, that is, the comparator module is electrically connected between the conversion module and the controller, and the comparator module is used to compare the voltage signal with the preset voltage range, and when the voltage signal is not within the preset voltage range, a preset level signal is sent to the controller.

[0035] Exemplary, reference Figure 1 The comparison circuit may include: two comparison branches, each comparison branch is electrically connected between the controller and the sampling resistor. The two comparison branches may be a first comparison branch and a second comparison branch. Figure 1 The upper half of the comparison circuit shown is the first comparison branch. Figure 1 The lower half of the comparison circuit shown is the second comparison branch. Exemplarily, the first comparison branch is used to detect the current flowing from the reference ground to the switch tube, and the second comparison branch is used to detect the current flowing from the switch tube to the reference ground, and when the current overload is collected, a preset level signal is sent to the controller to control the switch tube to turn off, terminate the current overload phenomenon between the switch tube and the reference ground, thereby realizing overcurrent protection for the bidirectional current of the switch tube.

[0036] Exemplarily, the preset voltage range includes a first voltage threshold and a second voltage threshold. The first comparison branch is used to convert the current signal flowing through the sampling resistor into a first voltage signal, and the first comparison branch is also used to compare the first voltage signal with the first voltage threshold of the preset voltage range. The first comparison branch is also used to send a preset level signal to the controller when the first voltage signal is greater than the first voltage threshold. Exemplarily, the first comparison branch can be used to sample the overcurrent of the current flow between the switch tube and the reference ground.

[0037] Exemplarily, the second comparison branch is used to convert the current signal flowing through the sampling resistor into a second voltage signal, and the second comparison branch is also used to compare the second voltage signal with a second voltage threshold of a preset voltage range. The second comparison branch is also used to send a preset level signal to the controller when the second voltage signal is less than the second voltage threshold. Exemplarily, the second comparison branch can be used to sample the overcurrent of the current flow direction between the reference ground and the switch tube.

[0038] It should be noted that the preset voltage range is determined based on the maximum allowable current range between the switch tube and the reference ground. For the convenience of the following description, the current flow direction from the switch tube to the reference ground can be the first flow direction, and the current flow direction from the reference ground to the switch tube can be the second flow direction. That is, the current flow direction from the switch tube → sampling resistor → reference ground is the first flow direction, and the current flow direction from the reference ground → sampling resistor → switch tube is the second flow direction. The maximum allowable current value of the first flow direction is the first current threshold, and the maximum allowable current value of the second flow direction is the second current threshold. Exemplarily, the first flow direction can be defined as a positive flow direction, and the second flow direction can be defined as a negative flow direction. Of course, in other embodiments, the first flow direction can also be defined as a negative flow direction, and the second flow direction can be defined as a positive flow direction. When the first flow direction is a positive flow direction, the first current threshold is a positive value, the second flow direction is a negative flow direction, and the second current threshold is a negative value. When the first flow direction is a negative flow direction, the first flow direction is a negative value, the second flow direction is a positive flow direction, and the second current threshold is a positive value. The maximum allowable current range between the switch tube and the reference ground is between a first current threshold in the first flow direction and a second current threshold in the second flow direction.

[0039] In some embodiments, the first voltage threshold of the preset voltage range is determined based on the first current threshold, and the second voltage threshold of the preset voltage range is determined based on the second current threshold. At this time, the first comparison branch can be used for overcurrent sampling of the current flow direction between the switch tube and the reference ground, and the second comparison branch can be used for overcurrent sampling of the current flow direction between the reference ground and the switch tube. Of course, in other embodiments, the second voltage threshold of the preset voltage range is determined based on the first current threshold, and the first voltage threshold of the preset voltage range is determined based on the first current threshold, so that the second comparison branch can be used for overcurrent sampling of the current flow direction between the switch tube and the reference ground, and the first comparison branch can be used for overcurrent sampling of the current flow direction between the reference ground and the switch tube.

[0040] When setting the first comparison branch, multiple methods may be used, and several methods are exemplarily introduced as follows.

[0041] Exemplary, reference Figure 1, the first comparison branch may include: a first comparator module, the first comparator module having a first input terminal, a second input terminal and a first output terminal. Among them, the first input terminal is used to input a first reference voltage signal whose voltage value is a first voltage threshold, that is, the first reference voltage signal represents the first voltage threshold of a preset voltage range. The second input terminal is used to input a first voltage signal, and the first voltage signal is a first voltage signal obtained by the first comparison branch converting a current signal flowing through a sampling resistor. The first output terminal is electrically connected to the controller, and the first output terminal is used to output a preset level signal to the controller when the first voltage signal is greater than the first reference voltage signal. It can be seen that the first comparator module is used to compare the magnitude of the first reference voltage signal and the first voltage signal. The comparison result of the first comparator module includes: the first voltage signal is not greater than the first reference voltage signal, or the first voltage signal is greater than the first reference voltage signal. When the comparison result of the first comparator module is that the first voltage signal is greater than the first reference voltage signal, a preset level signal is output to the controller, triggering the controller to control the switch tube to close, so as to perform overcurrent protection on the switch tube.

[0042] It should be noted that the first input terminal and the second input terminal may be the positive input terminal and the negative input terminal of the first comparator module, respectively. Figure 2 and Figure 3 The "+" in the figure indicates the positive input terminal of the comparator module, and the "-" indicates the negative input terminal of the comparator module. Figure 2 In the embodiment, the second input terminal is the positive input terminal of the first comparator module, and the first input terminal is the negative input terminal of the first comparator module. Figure 3 In the embodiment, the second input terminal is the negative input terminal of the first comparator module, and the first input terminal is the positive input terminal of the first comparator module.

[0043] Exemplary, reference Figure 1 , Figure 2 and Figure 3 , the first comparison branch may also include: a first reference voltage branch. The first reference voltage branch is electrically connected between the voltage input terminal and the first input terminal. The first reference voltage branch is used to divide the reference voltage output from the voltage input terminal into a first reference voltage signal, and input the first reference voltage signal to the first input terminal. That is, the first reference voltage branch is used to input the first reference voltage signal to the first input terminal of the first comparator module according to the reference voltage output from the voltage input terminal.

[0044] When setting the first reference voltage branch, various methods may be used. Figure 1The first reference voltage branch may include: a first resistor, and a first reference resistor and a second reference resistor connected in series through a first node. The two ends of the first reference resistor are respectively electrically connected to the positive electrode of the voltage input terminal and the first node, the two ends of the second reference resistor are respectively electrically connected to the negative electrode of the voltage input terminal and the first node, and the first current limiting resistor is electrically connected between the first node and the first input terminal. Figure 1 R14 in the figure represents the first resistor. Figure 1 J1 in represents the first node, such as Figure 1 R5 in the figure represents the first reference resistor. Figure 1 R7 in the figure represents the second reference resistor. When the reference voltage outputted from the positive electrode of the voltage input terminal is determined, the voltage value of the voltage signal inputted to the first input terminal of the first comparator module can be made equal to the first voltage threshold value of the preset voltage range by adjusting the resistance values ​​of the first reference resistor, the second reference resistor and the first resistor.

[0045] Exemplary, reference Figure 1 , the first comparison branch may also include: a first conversion module. The first conversion module is electrically connected between the first end of the sampling resistor, the positive pole of the voltage input terminal, and the second input terminal. The first conversion module is used to convert the current signal flowing through the sampling resistor into a first voltage signal, and input the first voltage signal into the second input terminal. Among them, the second end of the sampling resistor is electrically connected to the reference ground, and the first conversion circuit is connected to the non-grounded end of the sampling resistor. In this embodiment, the non-grounded end of the sampling resistor is not directly connected to the second input terminal of the first comparator module, but by setting the first conversion module between the sampling resistor and the first comparator module, the voltage signal of the non-grounded end of the sampling resistor is adjusted to obtain the first voltage signal, and then the first voltage signal is input to the second input terminal of the first comparator module, so that it can be adjusted according to the overcurrent parameter, the resistance value of the sampling resistor, etc. Of course, in other embodiments, the first end of the sampling resistor can be directly connected to the second input terminal of the first comparison.

[0046] When setting the first conversion module, various methods may be used. For example, refer to Figure 1 , the first conversion module includes: a second resistor, and a first voltage-dividing resistor and a second voltage-dividing resistor connected in series through a second node. The two ends of the first voltage-dividing resistor are electrically connected to the first end of the sampling resistor and the second node respectively. The two ends of the second voltage-dividing resistor are electrically connected to the second node and the positive electrode of the voltage input terminal respectively. The second resistor is electrically connected between the second node and the second input terminal. Figure 1 R3 in the figure represents the second resistor. Figure 1 R2 in the figure represents the second voltage divider resistor. Figure 1 R1 in the figure represents the first voltage-dividing resistor. Figure 1J2 in the figure represents the second node. Through this connection mode, the proportional relationship between the first voltage signal and the voltage signal between the non-grounded end of the sampling resistor can be adjusted by adjusting the resistance value relationship of the first voltage divider resistor, the second voltage divider resistor, the second resistor, and the sampling resistor.

[0047] When setting the second comparator module, multiple methods may be used, and several setting methods are exemplarily introduced as follows.

[0048] Exemplary, reference Figure 1 , the second comparison branch may include: a second comparator module, the second comparator module has a third input terminal, a fourth input terminal and a second output terminal. Among them, the third input terminal is used to input a second reference voltage signal whose voltage value is a second voltage threshold, that is, the second reference voltage signal represents a second voltage threshold of a preset voltage range. The fourth input terminal is used to input a second voltage signal, and the second voltage signal is a second voltage signal obtained by the second comparison branch converting the current signal flowing through the sampling resistor. The second output terminal is electrically connected to the controller, and is used to output a preset level signal to the controller when the second voltage signal is less than the second reference voltage signal. It can be seen that the second comparator module is used to compare the magnitude of the second reference voltage signal and the second voltage signal. The comparison result of the second comparator module includes: the second voltage signal is less than the second reference voltage signal, or the second voltage signal is not less than the second reference voltage signal. When the comparison result of the second comparator module is that the second voltage signal is less than the second reference voltage signal, the preset level signal is output to the controller, triggering the controller to control the switch tube to close, so as to perform overcurrent protection on the switch tube.

[0049] It should be noted that the third input terminal and the fourth input terminal may be the positive input terminal and the negative input terminal of the second comparator module respectively. Figure 2 and Figure 3 The "+" in the figure indicates the positive input terminal of the comparator module, and the "-" indicates the negative input terminal of the comparator module. Figure 2 In the example, the third input terminal is the positive input terminal of the second comparator module, and the fourth input terminal is the negative input terminal of the second comparator module. Figure 3 In the embodiment, the third input terminal is the negative input terminal of the second comparator module, and the fourth input terminal is the positive input terminal of the second comparator module.

[0050] Exemplary, reference Figure 1, the second comparison branch may also include: a second reference voltage branch. The second reference voltage branch is electrically connected between the voltage input terminal and the third input terminal. The second reference voltage branch is used to divide the reference voltage output from the voltage input terminal into a second reference voltage signal, and input the second reference voltage signal to the third input terminal. That is, the second reference voltage branch is used to input the second reference voltage signal to the third input terminal of the second comparator module according to the reference voltage output from the voltage input terminal.

[0051] When setting the second reference voltage branch, various methods can be used. Figure 1 , the second reference voltage branch includes: a third resistor, and a third reference resistor and a fourth reference resistor connected in series through a third node. The two ends of the third reference resistor are respectively electrically connected to the positive electrode of the voltage input terminal and the third node, and the two ends of the fourth reference resistor are respectively electrically connected to the negative electrode of the voltage input terminal and the third node; the third resistor is electrically connected between the third node and the third input terminal. Figure 1 R10 in the figure represents the third resistor. Figure 1 J3 in represents the third node, such as Figure 1 R9 in the figure represents the third reference resistor. Figure 1 R8 in the figure represents the fourth reference resistor. When the reference voltage outputted from the positive electrode of the voltage input terminal is determined, the voltage value of the voltage signal inputted to the third input terminal of the second comparator module can be made equal to the second voltage threshold value of the preset voltage range by adjusting the resistance values ​​of the third reference resistor, the fourth reference resistor and the third resistor.

[0052] Exemplary, reference Figure 1 , the second comparison branch may also include: a second conversion module. The second conversion module is electrically connected between the first end of the sampling resistor, the positive pole of the voltage input terminal, and the fourth input terminal. The second conversion module is used to convert the current signal flowing through the sampling resistor into a second voltage signal, and input the second voltage signal into the fourth input terminal. Among them, the second end of the sampling resistor is electrically connected to the reference ground, and the second conversion circuit is connected to the non-grounded end of the sampling resistor. In this embodiment, the non-grounded end of the sampling resistor is not directly connected to the fourth input terminal of the second comparator module, but by setting the second conversion module between the sampling resistor and the second comparator module, the voltage signal of the non-grounded end of the sampling resistor is adjusted to obtain the second voltage signal, and then the second voltage signal is input to the fourth input terminal of the second comparator module, so that it can be adjusted according to the overcurrent parameter, the resistance value of the sampling resistor, etc. Of course, in other embodiments, the first end of the sampling resistor can be directly connected to the fourth input terminal of the second comparison.

[0053] When setting the second conversion module, multiple methods can be used. For example, refer to Figure 1, the second conversion module may include: a fourth resistor, and a third voltage-dividing resistor and a fourth voltage-dividing resistor connected in series through a fourth node. The two ends of the third voltage-dividing resistor are electrically connected to the first end of the sampling resistor and the fourth node respectively. The two ends of the fourth voltage-dividing resistor are electrically connected to the fourth node and the positive electrode of the voltage input terminal respectively. The fourth resistor is electrically connected between the fourth node and the fourth input terminal. Figure 1 R11 in the figure represents the fourth resistor. Figure 1 J4 in represents the fourth node, such as Figure 1 R13 in the figure represents the third voltage divider resistor. Figure 1 R12 in the figure represents the fourth voltage-dividing resistor. With this connection mode, the proportional relationship between the second voltage signal and the voltage signal between the non-grounded end of the sampling resistor can be adjusted by adjusting the resistance values ​​of the third voltage-dividing resistor, the fourth voltage-dividing resistor, the fourth resistor, and the sampling resistor.

[0054] Exemplary, reference Figure 1 An isolation capacitor C1 may be set between the reference ground and the fourth node J4, an isolation capacitor C2 may be set between the reference ground and the third node J3, an isolation capacitor C3 may be set between the reference ground and the second node J2, and an isolation capacitor C4 may be set between the reference ground and the first node J1 to achieve isolation and prevent signal interference.

[0055] Combine as follows Figure 1 , the working principle of current overcurrent protection is introduced by way of example.

[0056] refer to Figure 1 The third reference resistor R9 and the fourth reference resistor R8 are connected in series and connected between the voltage input terminal and the reference ground, and the voltage division value obtained by the two resistors (R9 and R8) is input into the third input terminal of the second comparator module. The second reference resistor R7 and the first reference resistor R5 are connected in series and connected between the voltage input terminal and the reference ground, and the voltage division value obtained by the two resistors (R7 and R5) is input into the first input terminal of the first comparator module.

[0057] like Figure 1 As shown, the second voltage-dividing resistor R2, the first voltage-dividing resistor R1 and the sampling resistor are connected in series and then connected between the voltage input terminal and the reference ground. The three resistors (R1, R2 and the sampling resistor) form a voltage divider at the second node J2 to obtain a value. When the switch tube is turned on, a large current flows from the power supply through the switch tube to the reference ground GND, which will cause the voltage at the second node J2 to increase. After the voltage is increased to exceed the set voltage at the first node J1, the first comparator module flips and inputs a preset level signal to the controller. After receiving the preset level signal, the controller turns off the switch tube and interrupts the loop, thereby realizing overcurrent protection between the switch tube and the reference ground.

[0058] For example, in Figure 2In the circuit diagram shown, the preset level signal can be a high level signal. Specifically, the positive input terminal of the first comparator module is the second input terminal, the negative input terminal of the first comparator module is the first input terminal, the positive input terminal of the second comparator module is the third input terminal, and the negative input terminal of the second comparator module is the fourth input terminal. At this time, the first output terminal and the second output terminal are connected through the series resistor R14 and the resistor R15, wherein the series node between the resistor R14 and the resistor R15 is also connected to the reference ground on the second comparator module. When the current exceeding the protection limit flows from the switch tube to the reference ground through the sampling resistor, the output level of the first comparator module is flipped to high, so that the controller receives a high level signal, and the controller stops working to control the switch tube to close.

[0059] For example, in Figure 3 In the circuit diagram shown, the preset level signal can be a low level signal. When the current exceeding the protection limit flows from the switch tube to the reference ground through the sampling resistor, the output level of the first comparator module flips to low, so that the controller receives a low level signal and stops working to control the switch tube to turn off.

[0060] Continue to refer Figure 1 The fourth voltage-dividing resistor R12, the third voltage-dividing resistor R13 and the sampling resistor are connected in series and then connected between the voltage input terminal and the reference ground. The three resistors (R12, R13 and the sampling resistor) form a voltage divider at the fourth node J4 to obtain a value. When a large current flows from the reference ground GND to the switch tube and forms a loop through other switching devices, if the voltage at the fourth node J4 is lower than the set voltage at the third node J3, the second comparator module flips and inputs a preset level signal to the controller. After receiving the preset level signal, the controller turns off the switch tube and interrupts the loop, thereby realizing overcurrent protection from the reference ground to the switch tube.

[0061] For example, in Figure 2 In the circuit diagram shown, the preset level signal can be a high level signal. When the current exceeding the protection limit flows from the reference ground through the sampling resistor to the switch tube, the output level of the second comparator module flips to high, so that the controller receives a high level signal and stops working to control the switch tube to turn off. For example, in Figure 3 In the circuit diagram shown, the preset level signal can be a low level signal. When the current exceeding the protection limit flows from the reference ground to the switch tube through the sampling resistor, the output level of the second comparator module flips to low, so that the controller receives a low level signal and stops working to control the switch tube to turn off.

[0062] For example, the resistance R of the resistor can be 10*10 -3Ω; R1 = R2 = R12 = R13 = 1000Ω; R5 = R8 = 7500; R7 = R9 = 9100; the reference voltage Vref output by the reference voltage source = 5V; then the voltage at the third node VJ3 = Vref*R8 / (R8+R9) = 2.259V; the voltage at the first node VJ1 = Vref*R7 / (R5+R7) = 2.741V. Assume that the point voltage between the switch tube and the sampling resistor is Vr, the current on the sampling resistor is Ir, the current from the switch tube to the reference ground is positive, that is, the first flow direction is the current positive direction; the current from the reference ground to the switch tube is negative, that is, the second flow direction is the current negative direction. The overcurrent protection limit is 48A, that is, the first current threshold is +48A, and the second current threshold is -48A.

[0063] If the following situation is encountered: the current on the resistor flows in the second direction. When Ir = -50A, the current exceeds the second current threshold; at this time, Vr = Ir*R = -0.5V.

[0064] The voltage at the second node VJ2 = (Vref-Vr)*R1 / (R1+R2)+Vr=2.25V;

[0065] The voltage at the fourth node VJ4 = (Vref-Vr)*R13 / (R12+R13)+Vr=2.25V;

[0066] VJ2<VJ1, the output of the first comparator module does not act, and does not output a preset level signal to the controller; VJ4<VJ3, the second comparator module outputs a preset level signal to the controller.

[0067] It should be noted that when Ir is -60A, VJ4=2.2V, and the voltage value of VJ4 decreases as the negative Ir increases. Therefore, when Ir<0A, VJ2<VJ1, the output of the first comparator module does not act, and will not output a preset level signal to the controller.

[0068] In the various embodiments shown above, by directly connecting the sampling resistor to the comparison circuit, the comparison circuit is used to convert the current signal flowing through the sampling resistor into a voltage signal, compare the voltage signal with a preset voltage range, and send a preset level signal to the controller when the voltage signal is not within the preset voltage range, so that the controller controls the switch tube to turn off, thereby realizing circuit protection when the switch tube is overcurrent. Compared with the prior art, the proportional amplifier circuit is omitted between the sampling resistor and the comparison circuit, which speeds up the response speed of the protection circuit and improves the effectiveness of the protection.

[0069] In addition, an embodiment of the present application further provides an electronic device, which includes: a switch tube, a controller, and an overcurrent protection circuit of any of the above switch tubes; wherein the controller is used to control the switch tube to turn off when a preset level signal is received. Exemplarily, the electronic device can be various electronic devices that require switch tubes, such as but not limited to smart wearable devices, smart phones, tablet computers, laptops, vehicle terminals, vehicle chargers, motor controllers, etc. Exemplarily, the switch tube can be various types of switch tubes, such as but not limited to MOS tubes and triodes. In some embodiments, the switch tube can be a switch tube in a bridge arm circuit, wherein the bridge arm circuit can be a power circuit such as but not limited to an electronic device.

[0070] The utility model has been described through the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the utility model to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the utility model is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the utility model, and these variations and modifications all fall within the scope of protection claimed by the utility model. The protection scope of the utility model is defined by the attached claims and their equivalents.

Claims

1. An overcurrent protection circuit for a switching tube, characterized in that: include: A sampling resistor, electrically connected between the output end of the switch tube and a reference ground; A comparison circuit comprises a comparator module and a conversion module connected to the sampling resistor; wherein the conversion module is used to convert a current signal flowing through the sampling resistor into a voltage signal; the comparator module is connected between the conversion module and a controller, the comparator module is used to compare the voltage signal with a preset voltage range, and when the voltage signal is not within the preset voltage range, sends a preset level signal to the controller; wherein the controller is used to control the switch tube to be turned off when receiving the preset level signal.

2. The overcurrent protection circuit according to claim 1, characterized in that: The comparison circuit comprises: a first comparison branch and a second comparison branch; the preset voltage range comprises a first voltage threshold and a second voltage threshold; Wherein, the first comparison branch is used to convert the current signal flowing through the sampling resistor into a first voltage signal, compare the first voltage signal with the first voltage threshold, and send the preset level signal to the controller when the first voltage signal is greater than the first voltage threshold; The second comparison branch is used to convert the current signal flowing through the sampling resistor into a second voltage signal, compare the second voltage signal with the second voltage threshold, and send the preset level signal to the controller when the second voltage signal is less than the second voltage threshold.

3. The overcurrent protection circuit according to claim 2, characterized in that: The current flowing from the switch tube to the reference ground is a first direction, and the current flowing from the reference ground to the switch tube is a second direction; the maximum allowable current value of the first direction is a first current threshold, and the maximum allowable current value of the second direction is a second current threshold; The first voltage threshold is determined according to the first current threshold, and the second voltage threshold is determined according to the second current threshold.

4. The overcurrent protection circuit according to claim 2, characterized in that: The first comparison branch comprises: a first comparator module, the first comparator module having a first input terminal, a second input terminal and a first output terminal; Among them, the first input terminal is used to input a first reference voltage signal whose voltage value is the first voltage threshold; the second input terminal is used to input the first voltage signal; the first output terminal is electrically connected to the controller, and is used to output the preset level signal to the controller when the first voltage signal is greater than the first reference voltage signal.

5. The overcurrent protection circuit according to claim 4, characterized in that: The first comparison branch also includes: a first reference voltage branch, electrically connected between the voltage input terminal and the first input terminal, for dividing the reference voltage output from the voltage input terminal into the first reference voltage signal, and inputting the first reference voltage signal into the first input terminal.

6. The overcurrent protection circuit according to claim 5, characterized in that: The first reference voltage branch comprises: A first reference resistor and a second reference resistor connected in series via a first node; wherein two ends of the first reference resistor are electrically connected to the positive electrode of the voltage input terminal and the first node respectively, and two ends of the second reference resistor are electrically connected to the negative electrode of the voltage input terminal and the first node respectively; The first resistor is electrically connected between the first node and the first input terminal.

7. The overcurrent protection circuit according to claim 4, characterized in that: The first comparison branch further includes: a first conversion module, electrically connected between the first end of the sampling resistor, the positive electrode of the voltage input end, and the second input end, for converting the current signal flowing through the sampling resistor into the first voltage signal, and inputting the first voltage signal into the second input end; Wherein, the second end of the sampling resistor is electrically connected to the reference ground.

8. The overcurrent protection circuit according to claim 7, characterized in that: The first conversion module comprises: A first voltage-dividing resistor and a second voltage-dividing resistor connected in series through a second node; wherein two ends of the first voltage-dividing resistor are electrically connected to a first end of the sampling resistor and the second node respectively; and two ends of the second voltage-dividing resistor are electrically connected to the second node and a positive electrode of the voltage input terminal respectively; The second resistor is electrically connected between the second node and the second input terminal.

9. The overcurrent protection circuit according to claim 2, characterized in that: The second comparison branch comprises: a second comparator module, the second comparator module having a third input terminal, a fourth input terminal and a second output terminal; Among them, the third input terminal is used to input a second reference voltage signal whose voltage value is the second voltage threshold; the fourth input terminal is used to input the second voltage signal; the second output terminal is electrically connected to the controller and is used to output the preset level signal to the controller when the second voltage signal is less than the second reference voltage signal.

10. The overcurrent protection circuit according to claim 9, characterized in that: The second comparison branch also includes: a second reference voltage branch, electrically connected between the voltage input terminal and the third input terminal, for dividing the reference voltage output from the voltage input terminal into the second reference voltage signal, and inputting the second reference voltage signal into the third input terminal.

11. The overcurrent protection circuit according to claim 10, characterized in that: The second reference voltage branch comprises: A third reference resistor and a fourth reference resistor connected in series via a third node; wherein two ends of the third reference resistor are electrically connected to the positive electrode of the voltage input terminal and the third node respectively, and two ends of the fourth reference resistor are electrically connected to the negative electrode of the voltage input terminal and the third node respectively; The third resistor is electrically connected between the third node and the third input terminal.

12. The overcurrent protection circuit according to claim 9, characterized in that: The second comparison branch further includes: a second conversion module, electrically connected between the first end of the sampling resistor, the positive electrode of the voltage input end, and the fourth input end, for converting the current signal flowing through the sampling resistor into the second voltage signal, and inputting the second voltage signal into the fourth input end; Wherein, the second end of the sampling resistor is electrically connected to the reference ground.

13. The overcurrent protection circuit according to claim 12, characterized in that: The second conversion module comprises: A third voltage-dividing resistor and a fourth voltage-dividing resistor connected in series through a fourth node; wherein two ends of the third voltage-dividing resistor are electrically connected to the first end of the sampling resistor and the fourth node respectively; and two ends of the fourth voltage-dividing resistor are electrically connected to the fourth node and the positive electrode of the voltage input terminal respectively; A fourth resistor is electrically connected between the fourth node and the fourth input terminal.

14. An electronic device, characterized in that: include: A switch tube, a controller, and an overcurrent protection circuit for the switch tube as claimed in any one of claims 1 to 13; wherein the controller is used to control the switch tube to be turned off when receiving the preset level signal.

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