Overcurrent detection circuit and device

Abstract

The application discloses an overcurrent detection circuit and device, which comprises a detection module and a signal output module, the input end of the detection module is connected with the detection end of an overcurrent detection object, and the output end of the detection module is connected with the input end of the signal output module; the detection module monitors the output voltage of the detection end, and outputs an overcurrent detection voltage to the signal output module when the output voltage is greater than an overcurrent protection voltage, the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object; and the signal output module outputs an overcurrent protection control signal according to the overcurrent detection voltage. In the application, the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object, and a current detection resistor is not additionally arranged, which can prevent the voltage drop and power loss on the current detection resistor, improve the output power and efficiency, and reduce the cost of the overcurrent detection circuit while ensuring the safe and reliable operation of the equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current detection, in particular to an overcurrent detection circuit and device. BACKGROUND

[0002] In the working process of the circuit, the current in the circuit generally needs to be detected to prevent the current in the circuit from exceeding the safe current. The traditional overcurrent detection circuit detects the current by connecting a current detection resistor in series on the current output path of the overcurrent detection object. However, the current detection resistor will generate a voltage drop and power loss, and the current detection resistor needs to have a good temperature coefficient to ensure the stability and accuracy of current detection, which increases the difficulty and cost of selecting the current detection resistor. Therefore, how to reduce the cost of the circuit while improving the output efficiency of the circuit has become a technical problem to be solved.

[0003] The above content is only used to assist in understanding the technical solutions of the present application and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0004] The main purpose of the present application is to provide an overcurrent detection circuit and device, which aims to solve the technical problems of high cost of overcurrent detection circuit and low output efficiency of circuit in the prior art.

[0005] To achieve the above purpose, the present application provides an overcurrent detection circuit, which comprises a detection module and a signal output module, the input end of the detection module is connected with the detection end of an overcurrent detection object, and the output end of the detection module is connected with the input end of the signal output module.

[0006] The detection module is used for monitoring the output voltage of the detection end, and outputting an overcurrent detection voltage to the signal output module when the output voltage is greater than an overcurrent protection voltage, wherein the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object.

[0007] The signal output module is used for outputting an overcurrent protection control signal according to the overcurrent detection voltage.

[0008] Optionally, the detection module comprises a switching unit, the first end of the switching unit is connected with the detection end of the overcurrent detection object, and the second end of the switching unit is connected with the input end of the signal output module.

[0009] The switching unit is used for connecting the loop in which the switching unit is located when the output voltage is greater than the overcurrent protection voltage, so as to output the overcurrent detection voltage to the signal output module through the loop.

[0010] Optionally, the detection module further comprises a filtering unit, and the filtering unit is connected with the switching unit in parallel.

[0011] The filter unit is configured to filter the sudden voltage when the voltage across the switch unit changes suddenly, so as to prevent the switch unit from malfunctioning.

[0012] Optionally, the overcurrent detection circuit further comprises a voltage dividing module, an input end of the voltage dividing module being connected with the second end of the switch unit, and an output end of the voltage dividing module being connected with an input end of the signal output module.

[0013] The voltage dividing module is configured to divide the overcurrent detection voltage and output the divided overcurrent detection voltage to the signal output module.

[0014] Optionally, the switch unit comprises a first triode and a first resistor, an emitter of the first triode being connected with the input end of the overcurrent detection object through a first diode, a base of the first triode being connected with a first end of the first resistor, and a second end of the first resistor being connected with the output end of the overcurrent detection object.

[0015] Optionally, the filter unit comprises a first capacitor, a first end of the first capacitor being connected with the emitter of the first triode, and a second end of the first capacitor being connected with the base of the first triode.

[0016] Optionally, the voltage dividing module comprises a second resistor, a first end of the second resistor being connected with a collector of the first triode.

[0017] Optionally, the signal output module comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a comparator and a seventh resistor, a first end of the third resistor being connected with a pull-up power supply, a second end of the third resistor being connected with a first end of the fourth resistor and an inverting input end of the comparator, a second end of the fourth resistor being connected with a negative rail voltage end, a first end of the fifth resistor being connected with the pull-up power supply, a second end of the fifth resistor being connected with a first end of the sixth resistor and a non-inverting input end of the comparator, a second end of the sixth resistor being connected with the second end of the fourth resistor, an output end of the comparator being connected with a first end of the seventh resistor, the non-inverting input end of the comparator being further connected with the second end of the second resistor, a second end of the seventh resistor being connected with a low-voltage power supply, and the output end of the comparator being configured to output an overcurrent protection control signal.

[0018] Optionally, the overcurrent detection object is a power transistor.

[0019] To achieve the above object, the application further provides an overcurrent detection device, which comprises the overcurrent detection circuit as described above.

[0020] The embodiment of the present application provides a kind of overcurrent detection circuit, the overcurrent detection circuit includes detection module and signal output module, the input of the detection module is connected with the detection end of overcurrent detection object, the output of the detection module is connected with the input of the signal output module;The detection module is used to monitor the output voltage of the detection end, and when the output voltage is greater than overcurrent protection voltage, overcurrent detection voltage is output to the signal output module, and the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object;The signal output module is used to output overcurrent protection control signal according to the overcurrent detection voltage.Detection module monitors the output voltage of overcurrent detection object detection end, and outputs overcurrent detection voltage to signal output module when the output voltage is greater than overcurrent protection voltage, to realize overcurrent detection, and the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object, without additional current detection resistor, on the one hand, it can prevent voltage drop and power loss on the current detection resistor, improve output power and efficiency, on the other hand, while ensuring the safe and reliable operation of equipment, reduce the cost of overcurrent detection circuit. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on the drawings shown.

[0022] Figure 1 The functional module diagram of the first embodiment of the overcurrent detection circuit of the present application is shown in the figure.

[0023] Figure 2 The functional module diagram of the second embodiment of the overcurrent detection circuit of the present application is shown in the figure.

[0024] Figure 3 The functional module diagram of the overcurrent detection circuit in an embodiment of the present application is shown in the figure.

[0025] Figure 4 The functional module diagram of the overcurrent detection circuit in an embodiment of the present application is shown in the figure.

[0026] Figure 5 The circuit structure schematic diagram of the third embodiment of the overcurrent detection circuit of the present application is shown in the figure.

[0027] Figure 6 The circuit structure schematic diagram of the overcurrent detection circuit in an embodiment of the present application is shown in the figure.

[0028] Figure 7Another circuit structure diagram for overcurrent detection of a power transistor in an embodiment of the overcurrent detection circuit of the present application.

[0029] Explanation of reference numerals:

[0030]

[0031] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0033] It should be noted that all directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the accompanying drawings), and if the certain posture changes, the directionality indications also change accordingly.

[0034] In addition, the descriptions of “first”, “second” and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first”, “second” can explicitly or implicitly include at least one of the features. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those skilled in the art, and when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0035] The embodiment of the present application provides an overcurrent detection circuit.

[0036] Reference Figure 1 , Figure 1 The functional module diagram of the first embodiment of the overcurrent detection circuit provided by the present application, in the embodiment, the overcurrent detection circuit comprises a detection module 10 and a signal output module 20, the input end of the detection module 10 is connected with the detection end of an overcurrent detection object A, and the output end of the detection module 10 is connected with the input end of the signal output module 20.

[0037] In the embodiment of the present application, the overcurrent detection circuit comprises a detection module and a signal output module. The detection module is connected with a detection end of an overcurrent detection object and is configured to monitor an output voltage of the detection end. The output voltage is generated based on an internal resistance of the overcurrent detection object and a current flowing through the overcurrent detection object. The detection module outputs an overcurrent detection voltage value signal when the output voltage of the detection end is greater than an overcurrent protection voltage. The signal output module outputs an overcurrent protection signal according to the overcurrent detection voltage.

[0038] It can be understood that the detection end can be a port provided on the overcurrent detection object and used for transmitting the output voltage.

[0039] The detection module 10 is configured to monitor the output voltage of the detection end and output an overcurrent detection voltage to the signal output module 20 when the output voltage is greater than an overcurrent protection voltage. The output voltage is generated based on an internal resistance of the overcurrent detection object and a current flowing through the overcurrent detection object.

[0040] It can be understood that the overcurrent protection voltage can be a voltage triggering the overcurrent protection of the overcurrent detection object. The voltage value of the overcurrent protection voltage is related to the overcurrent detection object.

[0041] The signal output module 20 is configured to output an overcurrent protection control signal according to the overcurrent detection voltage.

[0042] It can be understood that the overcurrent protection control signal can be a signal controlling the overcurrent protection of the overcurrent detection object.

[0043] In an example, the overcurrent detection object is a power transistor. During the operation of the power transistor, the detection module is connected with a drain of the power transistor and monitors the voltage of the drain. If the current flowing through the power transistor is lower than a safe current, the detection module does not output an overcurrent detection voltage. If the current flowing through the power transistor increases, the voltage drop generated on the on-resistance of the power transistor increases. When the voltage drop is greater than the overcurrent protection voltage, the detection module outputs an overcurrent detection voltage value signal. The signal output module outputs an overcurrent protection control signal according to the overcurrent detection voltage. After the overcurrent protection control signal is received by a subsequent circuit, the power transistor is controlled to stop working, so as to prevent the power transistor from being damaged due to overcurrent.

[0044] The embodiment of the present application provides a kind of overcurrent detection circuit, the overcurrent detection circuit includes detection module and signal output module, the input of the detection module is connected with the detection end of overcurrent detection object, the output of the detection module is connected with the input of the signal output module;The detection module is used to monitor the output voltage of the detection end, and when the output voltage is greater than overcurrent protection voltage, overcurrent detection voltage is output to the signal output module, the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object;The signal output module is used to output overcurrent protection control signal according to the overcurrent detection voltage.In the embodiment of the present application, the output voltage of the detection end of overcurrent detection object is monitored by detection module, and overcurrent detection voltage is output to signal output module when the output voltage is greater than overcurrent protection voltage, to realize overcurrent detection, the output voltage is generated based on the internal resistance of the overcurrent detection object and the current flowing through the overcurrent detection object, without additional current detection resistance, on the one hand, it can prevent the voltage drop and power loss on the current detection resistance, improve the output power and efficiency, on the other hand, while ensuring the safe and reliable operation of equipment, the cost of overcurrent detection circuit is reduced.

[0045] Reference Figure 2 , Figure 2 The function module diagram of the second embodiment of the overcurrent detection circuit provided by the present application, in the embodiment, the detection module 10 includes switch unit 101, the first end of the switch unit 101 is connected with the detection end of the overcurrent detection object, and the second end of the switch unit 101 is connected with the input of the signal output module 20.

[0046] In the embodiment of the present application, the detection module includes switch unit, the first end of the switch unit is connected with the detection end of the overcurrent detection object, and the second end of the switch unit is connected with the input of the signal output module, and the switch unit is connected with the detection end when the output voltage is greater than overcurrent protection voltage, to output overcurrent detection voltage to the signal output module through the closed loop.

[0047] The switch unit 101 is used to connect the loop in which the switch unit 101 is located when the output voltage is greater than overcurrent protection voltage, to output overcurrent detection voltage to the signal output module 20 through the loop.

[0048] It can be understood that if the output voltage is less than or equal to overcurrent protection voltage, the switch unit does not connect the loop in which the switch unit is located, and the overcurrent detection voltage cannot be output to the signal output module, and the signal output module does not act;If the output voltage is greater than overcurrent protection voltage, the switch unit connects the loop in which the switch unit is located, and overcurrent detection voltage is output to the signal output module through the closed loop.

[0049] In one example, if the current flowing through the overcurrent detection object is lower than the safe limit current, the output voltage is lower than the overcurrent protection voltage, the switch unit does not turn on the circuit in which it is located, and the signal output module does not act; if the current flowing through the overcurrent detection object is greater than the safe limit current, the output voltage is greater than the overcurrent protection voltage, at this time the switch unit turns on the circuit in which it is located, and outputs the overcurrent detection voltage to the signal output module through the turned-on circuit, the signal output module outputs the overcurrent protection control signal based on the received overcurrent detection voltage, and the rear-stage circuit controls the overcurrent detection object to stop working when the overcurrent protection control signal is received, so as to prevent the overcurrent detection object from being damaged.

[0050] In one optional embodiment, referring to Figure 3 , the detection module further comprises a filter unit 102, which is connected in parallel with the switch unit 101.

[0051] In the embodiment of the application, the filter unit is connected in parallel with the switch unit, and the filter unit filters the sudden voltage when the voltage across the switch unit changes suddenly, so as to prevent the switch unit from malfunctioning due to the interference voltage.

[0052] The filter unit 102 is configured to filter the sudden voltage when the voltage across the switch unit 101 changes suddenly, so as to prevent the switch unit 101 from malfunctioning.

[0053] In one example, if the current flowing through the overcurrent detection object is lower than the safe limit current, at this time the output voltage is greater than the overcurrent protection voltage due to external interference, at this time the filter unit acts to filter the sudden voltage, so that the switch unit is not turned on, and the overcurrent detection object that is normally working is prevented from stopping working, thereby improving the accuracy of overcurrent detection.

[0054] In one optional embodiment, referring to Figure 4 , the overcurrent detection circuit further comprises a voltage dividing module 30, an input end of the voltage dividing module 30 is connected with the second end of the switch unit 101, and an output end of the voltage dividing module 30 is connected with an input end of the signal output module 20.

[0055] In the embodiment of the application, the voltage dividing module is connected in series between the detection module and the signal output module, the overcurrent detection voltage output by the detection module is divided by the voltage dividing module before being transmitted to the signal output module, so as to prevent the signal output module from being damaged due to excessively high voltage.

[0056] The voltage dividing module 30 is configured to divide the overcurrent detection voltage and output the divided overcurrent detection voltage to the signal output module 20.

[0057] The detection module in the embodiment of the application comprises a switching unit, a first end of the switching unit is connected with a detection end of the overcurrent detection object, and a second end of the switching unit is connected with an input end of the signal output module; the switching unit is used for conducting a loop in which the switching unit is located when the output voltage is greater than the overcurrent protection voltage, so as to output the overcurrent detection voltage to the signal output module through the loop. The switching unit in the embodiment of the application conducts the loop in which the switching unit is located when the output voltage is greater than the overcurrent protection voltage, and outputs the overcurrent detection voltage to the signal output module through the conducted loop, thereby reducing the power loss caused by the current detection resistor and improving the output efficiency of the circuit.

[0058] With reference to Figure 5 , Figure 5 The functional module diagram of the third embodiment of the overcurrent detection circuit provided by the application is shown in the figure. In the embodiment, the switching unit 101 comprises a first triode T1 and a first resistor R1, the emitter of the first triode T1 is connected with the input end of the overcurrent detection object through a first diode D1, the base of the first triode T1 is connected with the first end of the first resistor R1, and the second end of the first resistor R1 is connected with the output end of the overcurrent detection object.

[0059] It can be understood that when the overcurrent detection object is not working, the emitter junction of the first triode T1 is not conducted, the first triode T1 is in a cut-off state, and the first resistor R1 provides a proper base current for the first triode T1.

[0060] In an optional embodiment, the filtering unit 102 comprises a first capacitor C1, the first end of the first capacitor C1 is connected with the emitter of the first triode T1, and the second end of the first capacitor C1 is connected with the base of the first triode T1.

[0061] It can be understood that the first capacitor C1 is connected with the base and the emitter of the first triode T1, the first capacitor C1 is a bypass capacitor, and the first capacitor C1 prevents the emitter junction of the first triode T1 from being mistakenly conducted when a sharp peak voltage appears between the base and the emitter of the first triode T1.

[0062] In an example, the conduction voltage of the emitter junction of the first triode T1 is 0.7V, the emitter junction of the first triode T1 is not conducted when the overcurrent detection object is working normally, a sharp peak voltage appears between the base and the emitter of the first triode T1 at a certain moment, and the sharp peak voltage is greater than 0.7V, at this moment, the first capacitor C1 is conducted, so that the emitter junction of the first triode T1 is not conducted, and the false action of the first triode T1 is prevented; if the output voltage of the detection end of the overcurrent detection object is greater than the overcurrent protection voltage, the first capacitor C1 is in an open circuit state, so that the emitter junction of the first triode T1 is conducted, and the overcurrent detection voltage is transmitted to the signal output module.

[0063] In an alternative embodiment, the voltage dividing module 30 comprises a second resistor R2, a first end of the second resistor R2 being connected to the collector of the first transistor T1.

[0064] It can be understood that the fifth resistor R5 is a voltage dividing resistor, preventing the overcurrent detection voltage input to the signal output module from being too high to damage the signal output module when the first transistor T1 is turned on.

[0065] In an alternative embodiment, continuing to refer to Figure 5 , the signal output module 20 comprises a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a comparator U and a seventh resistor R7, a first end of the third resistor R3 being connected to the pull-up power supply Vpull, a second end of the third resistor R3 being connected to a first end of the fourth resistor R4 and an inverting input terminal of the comparator U, a second end of the fourth resistor R4 being connected to a negative rail voltage terminal, a first end of the fifth resistor R5 being connected to the pull-up power supply Vpull, a second end of the fifth resistor R5 being connected to a first end of the sixth resistor R6 and a non-inverting input terminal of the comparator U, a second end of the sixth resistor R6 being connected to the second end of the fourth resistor R4, an output terminal of the comparator U being connected to a first end of the seventh resistor R7, the non-inverting input terminal of the comparator U also being connected to a second end of the second resistor R2, a second end of the seventh resistor R7 being connected to a low voltage power supply VCC, the output terminal of the comparator U being used to output an overcurrent protection control signal.

[0066] It can be understood that when the first transistor T1 is in an off state, the voltage at the non-inverting input terminal of the comparator U is: IN +=V N +(Vpull-V N )*R6 / (R5+R6), and the voltage at the inverting input terminal of the comparator U is: IN -=V N +(Vpull-V N )*R4 / (R3+R4), under the condition that Vpull>V N , and the resistance values R5=R4>R3=R6, the following can be obtained: IN+ <V IN , and the output Vout of the comparator U is a low level. If the overcurrent detection object is working normally, the output terminal of the comparator outputs a low level; if the current of the overcurrent detection object is greater than the safe limit current, the emitter junction of the first transistor T1 is turned on, the voltage at the non-inverting input terminal of the comparator U is pulled up to Vp, the voltage at the non-inverting input terminal of the comparator is higher than the voltage at the inverting input terminal of the comparator, and the output terminal of the comparator outputs a high level signal, which is the overcurrent protection control signal.

[0067] In an alternative embodiment, the overcurrent detection object is a power transistor.

[0068] In one example, referring to Figure 6 For example, the overcurrent detection object is a power transistor Q1, the overcurrent detection circuit according to the embodiments of the present application detects the overcurrent of the power transistor Q1, the first diode D1 prevents the drain voltage of the power transistor from flowing back to the gate, thereby ensuring the safety of the power transistor Q1, the eighth resistor R8 is a voltage dividing resistor, the D1 has a low conduction voltage, which ensures that the first transistor T1 is not turned on when the circuit is working normally, the R2 is a voltage dividing resistor, which prevents the comparator from being damaged due to the excessively high voltage of the non-inverting input terminal of U when the first transistor T1 is turned on, the R1 provides a proper base current for the first transistor, the C1 is a bypass capacitor, which prevents the emitter junction of the first transistor T1 from being mis-conducted due to the voltage spikes at the base and emitter of the first transistor T1, the R3, R4, R5 and R6 are voltage dividing resistors, one end of the R3 and R5 is connected to the pull-up voltage Vpull, one end of the R2 and R4 is connected to the negative rail voltage VN, which provides a proper static voltage for the non-inverting input terminal and the inverting input terminal of U, the R7 is a pull-up resistor for the output of the comparator; Vp>Vpull, during the normal operation of the power transistor Q1, the base-emitter voltage of the first transistor T1 is less than the conduction voltage, the first transistor T1 is not turned on, and the U outputs a low level signal; if the current flowing through the power transistor Q1 increases, the voltage across the power transistor Q1 increases, the base-emitter voltage of the first transistor T1 increases, and when the voltage increases to the conduction voltage of the first transistor T1, the first transistor T1 is turned on, the voltage at the collector of the first transistor T1 is pulled up to Vp, and after being divided by the R2, the voltage is applied to the non-inverting input terminal of U, at this time, the voltage at the non-inverting input terminal of U is higher than that at the inverting input terminal of U, the U outputs a high level signal, i.e., an overcurrent protection control signal, and the current in the subsequent stage outputs a low level signal through the Control terminal when receiving the overcurrent protection control signal, so that the power transistor Q1 stops working.

[0069] In another example, referring to Figure 7For example, the overcurrent detection object is a power transistor, the overcurrent detection circuit provided by the embodiment of the application performs overcurrent detection on two power transistors Q1 and Q2, the ninth resistor R9 is a voltage dividing resistor, the tenth resistor R10 provides a proper base current for the second transistor T2, the second capacitor C2 is a bypass capacitor, and the Gate Driver is a driving module for driving Q1 and Q2 to work; when the power transistors Q1 and Q2 are turned off at the same time, the emitter junction of T1 and T2 is not conductive, so that the transistors T1 and T2 are in the off state, the voltage at the same-phase input end of the comparator U is VIN+ = VN + (Vpull-VN) * R6 / (R5+R6), the voltage at the opposite-phase input end of the comparator U is VIN- = VN + (Vpull-VN) * R4 / (R3+R4), and when Vpull > VN and the resistance values of R4 = R5 > R3 = R6, VIN+ < VIN-, and the output Vout of U is at a low level. When the power transistor Q1 is turned on and the power transistor Q2 is turned off, the current flows through the drain and source of Q1 and generates a voltage drop on the on-resistance RDS1(ON) of Q1, and as the output current IOUT1 of Q1 increases, the voltage drop on Q1 also increases. Assuming that the forward conduction voltage of the first diode D1 is VF1 and the forward conduction voltage of the emitter junction of the first transistor T1 is 0.7 V, the emitter-base voltage VEB1 of T1 is VEB1 = VF1 + IOUT1 * RDS1(ON), and when the output current IOUT1 increases to a certain degree, the emitter junction of T1 is forward conductive, at this time, IOUT1 = (0.7 V-VF1) / RDS1(ON), the input voltage VIN+ at the same-phase input end of the comparator U increases, so that VIN+ > VIN-, and the output level of U is inverted from a low level to a high level, that is, an overcurrent protection control signal, and after the overcurrent protection control signal is received by the subsequent processing circuit, the output of the gate driver (Gate Driver) is controlled to turn off Q1, so that the output current of Q1 is reduced, and the overcurrent protection of Q1 is realized. When the power transistor Q1 is turned off and the power transistor Q2 is turned on, the current flows through the drain and source of Q2 and generates a voltage drop on the on-resistance RDS2(ON) of Q2, and as the output current flowing through Q2 increases, the voltage drop also increases. Assuming that the forward conduction voltage of the second diode D2 is VF2 and the forward conduction voltage of the emitter junction of the second transistor T2 is 0.7 V, the base-emitter voltage VBE2 of T2 is VBE2 = VF2 + IOUT2 * RDS2(ON), and when the output current IOUT2 increases to a certain degree, the emitter junction of T2 is forward conductive, at this time, IOUT2 = (0.7 V-VF2) / RDS2(ON), so that the input voltage VIN- at the opposite-phase input end of the comparator U decreases, so that VIN+ > VIN-, and the output level of U is inverted from a low level to a high level, and after the level change is received by the subsequent processing circuit, the output of the gate driver is controlled to turn off Q2, so that the output current is reduced, and the purpose of protecting the power transistor is achieved.

[0070] In the embodiment of the present application, the on-resistance RDS(ON) of the power transistor is directly used as the overcurrent detection resistance, and no additional current detection resistance is needed, which can prevent voltage drop and power loss on the current detection resistance, improve the output power and output efficiency, and reduce the design cost of the protection circuit while ensuring safe and reliable operation of the device, thereby improving the cost performance of the device.

[0071] The switch unit in the embodiment of the present application includes a first transistor and a first resistor, the emitter of the first transistor is connected to the input end of the overcurrent detection object through a first diode, the base of the first transistor is connected to the first end of the first resistor, and the second end of the first resistor is connected to the output end of the overcurrent detection object. The switch unit in the embodiment of the present application includes a first transistor and a first resistor, when the current flowing through the overcurrent detection object increases and the output voltage is greater than the on-voltage of the first transistor, the first transistor is turned on, the input voltage of the positive input end of the comparator is pulled up, the output voltage of the comparator is converted from low to high, and thus the overcurrent detection and overcurrent protection of the overcurrent detection object are realized, no additional current detection resistance is needed, the loss caused by the current detection resistance is reduced, and the output efficiency of the circuit is improved.

[0072] To achieve the above object, the present application further provides an overcurrent detection device, which includes the overcurrent detection circuit as described above. The specific structure of the circuit is referred to the above embodiments, and since the device adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0073] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made according to the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. An overcurrent detection circuit, characterized by comprising: The overcurrent detection circuit comprises a detection module and a signal output module, an input end of the detection module is connected with a detection end of an overcurrent detection object, an output end of the detection module is connected with an input end of the signal output module, the detection end is a port arranged on the overcurrent detection object, and the detection end is used for transmitting an output voltage; The detection module is used for monitoring the output voltage of the detection end, and outputs an overcurrent detection voltage to the signal output module when the output voltage is greater than an overcurrent protection voltage, the output voltage is generated based on an internal resistance of the overcurrent detection object and a current flowing through the overcurrent detection object; The signal output module is used for outputting an overcurrent protection control signal according to the overcurrent detection voltage.

2. The overcurrent detection circuit of claim 1, wherein, The detection module comprises a switching unit, a first end of the switching unit is connected with the detection end of the overcurrent detection object, and a second end of the switching unit is connected with the input end of the signal output module; The switching unit is used for turning on a loop in which the switching unit is located when the output voltage is greater than the overcurrent protection voltage, so as to output the overcurrent detection voltage to the signal output module through the loop.

3. The overcurrent detection circuit of claim 2, wherein, The detection module further comprises a filtering unit, and the filtering unit is connected with the switching unit in parallel; The filtering unit is used for filtering a sudden change voltage when the voltage between the switching unit and the filtering unit suddenly changes, so as to prevent the switching unit from malfunctioning.

4. The overcurrent detection circuit of claim 3, wherein, The overcurrent detection circuit further comprises a voltage dividing module, an input end of the voltage dividing module is connected with the second end of the switching unit, and an output end of the voltage dividing module is connected with the input end of the signal output module; The voltage dividing module is used for dividing the overcurrent detection voltage and outputting the divided overcurrent detection voltage to the signal output module.

5. The overcurrent detection circuit of claim 4, wherein, The switching unit comprises a first triode and a first resistor, an emitter of the first triode is connected with an input end of the overcurrent detection object through a first diode, a base of the first triode is connected with a first end of the first resistor, and a second end of the first resistor is connected with an output end of the overcurrent detection object.

6. The overcurrent detection circuit of claim 5, wherein, The filtering unit comprises a first capacitor, a first end of the first capacitor is connected with the emitter of the first triode, and a second end of the first capacitor is connected with the base of the first triode.

7. The overcurrent detection circuit of claim 6, wherein, The voltage dividing module comprises a second resistor, a first end of the second resistor is connected with a collector of the first triode.

8. The overcurrent detection circuit of claim 7, wherein, The signal output module comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a comparator and a seventh resistor, a first end of the third resistor is connected with a pull-up power supply, a second end of the third resistor is connected with a first end of the fourth resistor and an inverting input end of the comparator, a second end of the fourth resistor is connected with a negative rail voltage end, a first end of the fifth resistor is connected with the pull-up power supply, a second end of the fifth resistor is connected with a first end of the sixth resistor and a non-inverting input end of the comparator, a second end of the sixth resistor is connected with the second end of the fourth resistor, an output end of the comparator is connected with a first end of the seventh resistor, the non-inverting input end of the comparator is also connected with a second end of the second resistor, a second end of the seventh resistor is connected with a low-voltage power supply, and the output end of the comparator is used for outputting an overcurrent protection control signal.

9. An overcurrent detection circuit as claimed in any one of claims 1 to 8, wherein The overcurrent detection object is a power transistor.

10. An overcurrent detection device, characterized by comprising: The overcurrent detection device comprises the overcurrent detection circuit according to any one of claims 1-9.

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