A MOSFET overcurrent protection circuit and a MOSFET device

Abstract

The present invention discloses a MOSFET overcurrent protection circuit and a MOSFET device. The overcurrent protection circuit includes: a first resistor, a current detection circuit, a logic comparison circuit, and a drive circuit; the current detection circuit is configured to detect the current flowing through the MOSFET and output it to the logic comparison circuit; the logic comparison circuit is configured to determine whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit when there is no overcurrent fault, and output a second level signal to the drive circuit when an overcurrent fault occurs; the drive circuit is configured to provide a drive signal required for turning on or off the MOSFET according to the first level signal or the second level signal. By providing the first resistor, the current detection circuit, the logic comparison circuit, and the drive circuit, overcurrent protection for the MOSFET is achieved, and the device can be turned off in a shorter time when an overcurrent fault occurs to protect the device.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics detection, and particularly to a MOSFET overcurrent protection circuit and a MOSFET device. Background Art

[0002] Compared with the traditional power transistor IGBT, the MOSFET can operate at high frequencies, and at the same time has low leakage current and switching losses, which is beneficial to improving the energy efficiency of electronic devices. In addition, the MOSFET also has the characteristic of radiation resistance, can work in a high-radiation environment, and has a small reverse recovery loss of the body diode, and can be used to realize high-speed switching. However, compared with the IGBT, the thinner gate dielectric layer and smaller chip size result in poorer short-circuit reliability of the MOSFET. Therefore, it requires a short-circuit protection circuit with better performance.

[0003] Currently, several common overcurrent protection methods are applied to MOSFETs. One is the desaturation technique, which directly detects the drain-source voltage of the device to determine whether the device has a fault. However, this technique is affected by a high voltage change rate and has a high delay. Another method is to sample the gate charge characteristic of the device to evaluate whether there is a Miller plateau to determine whether the device has a fault. However, this method has certain limitations, such as a complex detection circuit, a large data processing difficulty, a large influence of the evaluation result on the environment, and easy misjudgment, etc. Summary of the Invention

[0004] The present invention provides a MOSFET overcurrent protection circuit and a MOSFET device to achieve overcurrent protection of the MOSFET, shorten the detection time, and be able to quickly turn off the device when an overcurrent fault occurs to protect the safety of the device.

[0005] According to one aspect of the present invention, a MOSFET overcurrent protection circuit is provided. The MOSFET overcurrent protection circuit includes: a first resistor, a current detection circuit, a logic comparison circuit, and a drive circuit;

[0006] Wherein, the first end of the first resistor is electrically connected to the drain of the MOSFET; the second end of the first resistor is electrically connected to the current detection circuit; the current detection circuit is also electrically connected to the MOSFET and the logic comparison circuit respectively; the logic comparison circuit is also electrically connected to the drive circuit; the drive circuit is also electrically connected to the gate of the MOSFET;

[0007] Wherein, the current detection circuit is used to detect the current flowing through the MOSFET and output it to the logic comparison circuit;

[0008] The logic comparison circuit is configured to determine whether an overcurrent fault occurs in the MOSFET according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit when no overcurrent fault occurs, or output a second level signal to the drive circuit when an overcurrent fault occurs;

[0009] The drive circuit is configured to provide a drive signal required for turning on or off the MOSFET to the MOSFET according to the first level signal or the second level signal.

[0010] Optionally, the current detection circuit includes a diode and a first capacitor; wherein, the anode of the diode is electrically connected to the second end of the first resistor, the cathode of the diode is respectively electrically connected to the first end of the first capacitor and the logic comparison circuit; the second end of the first capacitor is respectively electrically connected to the drain of the MOSFET, the first end of the first resistor, and the logic comparison circuit.

[0011] Optionally, the logic comparison circuit includes a current-voltage conversion unit, a voltage comparison unit, and a level signal output unit; wherein, the current-voltage conversion unit is respectively electrically connected to the current detection circuit and the voltage comparison unit; the voltage comparison unit is further electrically connected to the level signal output unit; the level signal output unit is further electrically connected to the drive circuit.

[0012] Optionally, the current-voltage conversion unit includes a first amplifier and a second capacitor; wherein, the first input terminal and the second input terminal of the first amplifier are both electrically connected to the current detection circuit; the output terminal of the first amplifier is respectively electrically connected to the first end of the second capacitor and the voltage comparison unit; the second end of the second capacitor is grounded.

[0013] Optionally, the current-voltage conversion unit further includes a second resistor; the first end of the second resistor is respectively electrically connected to the current detection circuit and the first input terminal of the first amplifier, and the second end of the second resistor is respectively electrically connected to the output terminal of the first amplifier, the first end of the second capacitor, and the voltage comparison unit.

[0014] Optionally, the voltage comparison unit includes a second amplifier; the first input terminal of the second amplifier is electrically connected to the current-voltage conversion unit, the second input terminal of the second amplifier is connected to a preset reference voltage; the output terminal of the second amplifier is electrically connected to the level signal output unit.

[0015] Optionally, the level signal output unit includes a flip-flop and a logical AND gate; wherein, the data input terminal of the flip-flop is grounded, the clock input terminal of the flip-flop is electrically connected to the voltage comparison unit, the inverted output terminal of the flip-flop is electrically connected to the first input terminal of the logical AND gate, and a preset PWM signal is input to the second input terminal of the logical AND gate; the output terminal of the logical AND gate is electrically connected to the drive circuit.

[0016] Optionally, the drive circuit is a push-pull drive circuit.

[0017] Optionally, the first level signal is a high level signal and the second level signal is a low level signal.

[0018] According to another aspect of the present invention, there is provided a MOSFET device, which includes the MOSFET overcurrent protection circuit as described in the first aspect.

[0019] The technical solution of the embodiment of the present invention provides a MOSFET overcurrent protection circuit and a MOSFET device. The MOSFET overcurrent protection circuit includes: a first resistor, a current detection circuit, a logic comparison circuit, and a drive circuit; wherein, the first end of the first resistor is electrically connected to the drain of the MOSFET; the second end of the first resistor is electrically connected to the current detection circuit; the current detection circuit is also electrically connected to the MOSFET and the logic comparison circuit respectively; the logic comparison circuit is also electrically connected to the drive circuit; the drive circuit is also electrically connected to the gate of the MOSFET; wherein, the current detection circuit is configured to detect the current flowing through the MOSFET and output it to the logic comparison circuit; the logic comparison circuit is configured to determine whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit when no overcurrent fault occurs, or output a second level signal to the drive circuit when an overcurrent fault occurs; the drive circuit is configured to provide a drive signal required for the MOSFET to turn on or off to the MOSFET according to the first level signal or the second level signal. It can be seen that by setting the first resistor, the current detection circuit, the logic comparison circuit, and the drive circuit, overcurrent protection of the MOSFET can be achieved, and compared with the traditional overcurrent protection circuit, this circuit has a shorter detection time, enabling the device to be turned off in a shorter time when the MOSFET has an overcurrent fault, thereby protecting the safe operation of the MOSFET device.

[0020] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 is the principle structural block diagram of a MOSFET overcurrent protection circuit provided in the embodiments of the present invention;

[0023] Figure 2 is the principle structural block diagram of another MOSFET overcurrent protection circuit provided in the embodiments of the present invention;

[0024] Figure 3 is the structural schematic diagram of a MOSFET overcurrent protection circuit provided in the embodiments of the present invention. Detailed implementation manners

[0025] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily need to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] Figure 1 is the principle structural block diagram of a MOSFET overcurrent protection circuit provided in the embodiments of the present invention. Refer to Figure 1, the MOSFET overcurrent protection circuit includes: a first resistor R1, a current detection circuit 10, a logic comparison circuit 20, and a drive circuit 30; wherein, the first end of the first resistor R1 is electrically connected to the drain of the MOSFET; the second end of the first resistor R1 is electrically connected to the current detection circuit 10; the current detection circuit 10 is also electrically connected to the MOSFET and the logic comparison circuit 20 respectively; the logic comparison circuit 20 is also electrically connected to the drive circuit 30; the drive circuit 30 is also electrically connected to the gate of the MOSFET; wherein, the current detection circuit 10 is used to detect the current flowing through the MOSFET and output it to the logic comparison circuit 20; the logic comparison circuit 20 is used to judge whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit 30 when there is no overcurrent fault, or output a second level signal to the drive circuit 30 when an overcurrent fault occurs; the drive circuit 30 is used to provide the drive signal required for the MOSFET to conduct or turn off to the MOSFET according to the first level signal or the second level signal.

[0028] Among them, the first resistor R1 is a sampling resistor. The specific resistance value of the first resistor R1 can be set according to the actual situation and will not be specifically limited here.

[0029] Among them, the logic comparison circuit 20 is used to judge whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a corresponding level signal to the drive circuit 30 according to the judgment result. For example, when the logic comparison circuit 20 judges that the MOSFET has no overcurrent fault, it outputs a first level signal to the drive circuit 30; when the logic comparison circuit 20 judges that the MOSFET has an overcurrent fault, it outputs a second level signal to the drive circuit 30.

[0030] Specifically, when the logic comparison circuit 20 judges that the MOSFET has no overcurrent fault, it outputs a first level signal to the drive circuit 30, and the drive circuit 30 provides the drive signal required for the MOSFET to conduct to the MOSFET according to the first level signal; when the logic comparison circuit 20 judges that the MOSFET has an overcurrent fault, it outputs a second level signal to the drive circuit 30, and the drive circuit 30 provides the drive signal required for the MOSFET to turn off to the MOSFET according to the second level signal.

[0031] Among them, the drive circuit 30 can adopt various traditional and common drive circuits, such as a push-pull drive circuit, etc. It can be specifically set according to the actual situation and will not be specifically limited here.

[0032] In the technical solution of this embodiment, the implementation process of the MOSFET overcurrent protection circuit is: Refer to Figure 1, the current detection circuit 10 detects the current flowing through the MOSFET and outputs it to the logic comparison circuit 20. The logic comparison circuit 20 determines whether the MOSFET has an overcurrent fault based on the received current flowing through the MOSFET. If it is determined that the MOSFET has not had an overcurrent fault, a first level signal is output to the drive circuit 30, and the drive circuit 30 provides the drive signal required for the MOSFET to conduct according to the first level signal; if it is determined that the MOSFET has an overcurrent fault, a second level signal is output to the drive circuit 30, and the drive circuit 30 provides the drive signal required for the MOSFET to turn off according to the second level signal. Thus, by detecting the current flowing through the MOSFET and determining whether the MOSFET has an overcurrent fault, rapid detection of whether the MOSFET has an overcurrent fault is achieved, and when it is detected that the MOSFET has an overcurrent fault, the MOSFET can be quickly turned off in a timely manner to protect the safety of the device. Compared with the existing overcurrent protection methods, it has a shorter detection time, and when the MOSFET has an overcurrent fault, the device can be turned off in a shorter time to protect the safe operation of the MOSFET device and avoid damaging the MOSFET device.

[0033] The technical solution of this embodiment provides a MOSFET overcurrent protection circuit, which includes: a first resistor, a current detection circuit, a logic comparison circuit, and a drive circuit; wherein, the first end of the first resistor is electrically connected to the drain of the MOSFET; the second end of the first resistor is electrically connected to the current detection circuit; the current detection circuit is also electrically connected to the MOSFET and the logic comparison circuit respectively; the logic comparison circuit is also electrically connected to the drive circuit; the drive circuit is also electrically connected to the gate of the MOSFET; wherein, the current detection circuit is used to detect the current flowing through the MOSFET and output it to the logic comparison circuit; the logic comparison circuit is used to determine whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit when there is no overcurrent fault, or output a second level signal to the drive circuit when there is an overcurrent fault; the drive circuit is used to provide the drive signal required for the MOSFET to conduct or turn off according to the first level signal or the second level signal. It can be seen from this that by setting the first resistor, the current detection circuit, the logic comparison circuit, and the drive circuit, overcurrent protection of the MOSFET can be achieved, and compared with the traditional overcurrent protection circuit, this circuit has a shorter detection time, and when the MOSFET has an overcurrent fault, the device can be turned off in a shorter time, thereby protecting the safe operation of the device.

[0034] On the basis of the above implementation, optionally, the first level signal is a high level signal, and the second level signal is a low level signal.

[0035] Among them, the first level signal and the second level signal are different level signals. Among them, the first level signal can also be a low-level signal, and the corresponding second level signal can also be a high-level signal. It should be noted that which of the first level signal and the second level signal is the high-level signal and which is the low-level signal can be set according to the actual situation and will not be specifically limited here.

[0036] Figure 2 is the principle structural block diagram of another MOSFET overcurrent protection circuit provided in the embodiment of the present invention. On the basis of the above embodiment, optionally, referring to Figure 2 , the logic comparison circuit 20 includes a current-voltage conversion unit 21, a voltage comparison unit 22, and a level signal output unit 23; among them, the current-voltage conversion unit 21 is electrically connected to the current detection circuit 10 and the voltage comparison unit 22 respectively; the voltage comparison unit 22 is also electrically connected to the level signal output unit 23; the level signal output unit 23 is also electrically connected to the drive circuit 30.

[0037] Among them, the current-voltage conversion unit 21 is used to convert the detected current flowing through the MOSFET into a voltage signal and output it to the voltage comparison unit 22 for comparison. Among them, the voltage comparison unit 22 is used to compare the voltage signal corresponding to the detected current flowing through the MOSFET with a preset reference voltage to determine whether the MOSFET has an overcurrent fault. Among them, the level signal output unit 23 is used to output a first level signal to the drive circuit 30 when the voltage comparison unit 22 determines that the MOSFET has not had an overcurrent fault, and output a second level signal to the drive circuit 30 when the voltage comparison unit 22 determines that the MOSFET has an overcurrent fault.

[0038] Among them, the specific implementation manner of the voltage comparison unit 22 for comparing the voltage signal corresponding to the detected current flowing through the MOSFET with a preset reference voltage to determine whether the MOSFET has an overcurrent fault can be: comparing the voltage signal corresponding to the detected current flowing through the MOSFET with a preset reference voltage. If the voltage corresponding to the detected current flowing through the MOSFET is less than the preset reference voltage, it is determined that the MOSFET has not had an overcurrent fault; if the voltage corresponding to the detected current flowing through the MOSFET is greater than the preset reference voltage, it is determined that the MOSFET has an overcurrent fault. Among them, the magnitude of the preset reference voltage can be set according to the actual situation and will not be specifically limited here.

[0039] In the technical solution of this embodiment, the implementation process of this MOSFET overcurrent protection circuit is: referring to Figure 2, the current detection circuit 10 detects the current flowing through the MOSFET and outputs it to the current-voltage conversion unit 21. The current-voltage conversion unit 21 converts the detected current flowing through the MOSFET into a corresponding voltage according to the received current and outputs it to the voltage comparison unit 22. The voltage comparison unit 22 compares the voltage signal corresponding to the detected current flowing through the MOSFET with a preset reference voltage to determine whether the MOSFET has an overcurrent fault. If the voltage corresponding to the detected current flowing through the MOSFET is less than the preset reference voltage, it is determined that the MOSFET has no overcurrent fault, and the level signal output unit outputs a first level signal to the drive circuit 30. The drive circuit 30 provides the drive signal required for the MOSFET to turn on according to the first level signal; if the voltage corresponding to the detected current flowing through the MOSFET is greater than the preset reference voltage, it is determined that the MOSFET has an overcurrent fault, and the level signal output unit outputs a second level signal to the drive circuit 30. The drive circuit 30 provides the drive signal required for the MOSFET to turn off according to the second level signal. Thus, by detecting the current flowing through the MOSFET, converting it into a corresponding voltage signal and comparing it with the preset reference voltage, it is possible to determine whether the MOSFET has an overcurrent fault, thereby achieving rapid detection of whether the MOSFET has an overcurrent fault, and being able to quickly turn off the MOSFET in time when it is detected that the MOSFET has an overcurrent fault to protect the safety of the device. Compared with the existing overcurrent protection methods, it has a shorter detection time, and can turn off the device in a shorter time when the MOSFET has an overcurrent fault to protect the safe operation of the device and avoid damaging the device.

[0040] Figure 3 is a schematic structural diagram of a MOSFET overcurrent protection circuit provided in an embodiment of the present invention. On the basis of the above implementation, optionally, refer to Figure 3 , the current detection circuit includes a diode D1 and a first capacitor C1; wherein, the anode of the diode D1 is electrically connected to the second end of the first resistor R1, and the cathode of the diode D1 is respectively electrically connected to the first end of the first capacitor C1 and the logic comparison circuit; the second end of the first capacitor C1 is respectively electrically connected to the drain of the MOSFET, the first end of the first resistor R1 and the logic comparison circuit.

[0041] Exemplarily, refer to Figure 3 , the anode of the diode D1 is electrically connected to the second end of the first resistor R1, and the cathode of the diode D1 is respectively electrically connected to the first end of the first capacitor C1 and the current-voltage conversion unit 21. The second end of the first capacitor C1 is respectively electrically connected to the drain of the MOSFET, the first end of the first resistor R1 and the current-voltage conversion unit 21.

[0042] Among them, the capacitance value of the first capacitor C1 can be set according to the actual situation and will not be specifically limited here.

[0043] Optionally, continue to refer to Figure 3 , the current-voltage conversion unit 21 includes a first amplifier COM1 and a second capacitor C2; among them, the first input terminal and the second input terminal of the first amplifier COM1 are both electrically connected to the current detection circuit 10; the output terminal of the first amplifier COM1 is respectively electrically connected to the first terminal of the second capacitor C2 and the voltage comparison unit 22; the second terminal of the second capacitor C2 is grounded.

[0044] Among them, the first amplifier COM1 is used to convert the detected current flowing through the MOSFET into a corresponding voltage signal and output it to the voltage comparison unit 22.

[0045] Among them, the first amplifier COM1 can be a high-speed operational amplifier.

[0046] Exemplarily, refer to Figure 3 , the first input terminal of the first amplifier COM1 is the non-inverting input terminal, and its second input terminal is the inverting input terminal. Refer to Figure 3 , the first input terminal of the first amplifier COM1 is respectively electrically connected to the cathode of the diode D1 and the first terminal of the first capacitor C1, and the second input terminal of the first amplifier COM1 is respectively electrically connected to the first terminal of the first resistor R1, the drain of the MOSFET, and the second terminal of the first capacitor C1.

[0047] Among them, the second capacitor C2 is used for filtering. Among them, the capacitance value of the second capacitor C2 can be set according to the actual situation and will not be specifically limited here.

[0048] Optionally, continue to refer to Figure 3 , the current-voltage conversion unit 21 further includes a second resistor R2; the first terminal of the second resistor R2 is respectively electrically connected to the current detection circuit 10 and the first input terminal of the first amplifier COM1, and the second terminal of the second resistor R2 is respectively electrically connected to the output terminal of the first amplifier COM1, the first terminal of the second capacitor C2, and the voltage comparison unit 22.

[0049] Among them, by adjusting the resistance value of the second resistor R2, the proportional relationship between the output signal and the input signal of the first amplifier COM1 can be adjusted, thereby adjusting the action threshold of the overcurrent protection circuit. Among them, the resistance value of the second resistor R2 can be specifically set according to the actual situation and will not be specifically limited here.

[0050] Exemplarily, refer to Figure 3, the first end of the second resistor R2 is electrically connected to the cathode of the diode D1, the first end of the first capacitor C1, and the first input terminal of the first amplifier COM1 respectively, and the second end of the second resistor R2 is electrically connected to the output terminal of the first amplifier COM1, the first end of the second capacitor C2, and the voltage comparison unit 22 respectively.

[0051] Optionally, continue to refer to Figure 3 , the voltage comparison unit 22 includes a second amplifier COM2; the first input terminal of the second amplifier COM2 is electrically connected to the current-voltage conversion unit 21, and the second input terminal of the second amplifier COM2 is connected to a preset reference voltage V ref ; the output terminal of the second amplifier COM2 is electrically connected to the level signal output unit 23.

[0052] Exemplarily, refer to Figure 3 , the first input terminal of the second amplifier COM2 is the non-inverting input terminal, and the second input terminal of the second amplifier COM2 is the inverting input terminal. The first input terminal of the second amplifier COM2 is electrically connected to the output terminal of the first amplifier COM1, the first end of the second capacitor C2, and the second end of the second resistor R2 respectively, and the second input terminal of the second amplifier COM2 is connected to a preset reference voltage; the output terminal of the second amplifier COM2 is electrically connected to the level signal output unit 23. Among them, the second amplifier COM2 is used to compare the voltage signal corresponding to the detected current flowing through the MOSFET received at its first input terminal with the preset reference voltage V ref to determine whether the MOSFET has an overcurrent fault.

[0053] Among them, the second amplifier COM2 can be a high-speed operational amplifier.

[0054] Optionally, continue to refer to Figure 3 , the level signal output unit 23 includes a flip-flop M1 and a logic AND gate M2; among them, the data input terminal D of the flip-flop M1 is grounded, the clock input terminal CLK of the flip-flop M1 is electrically connected to the voltage comparison unit 22, and the inverting output terminal of the flip-flop M1 is electrically connected to the first input terminal of the logic AND gate M2, and the second input terminal of the logic AND gate M2 is connected to a preset PWM signal; the output terminal of the logic AND gate M2 is electrically connected to the drive circuit 30.

[0055] Among them, the flip-flop M1 can be a D flip-flop.

[0056] Among them, the preset PWM signal can be a high-level signal.

[0057] Under normal circumstances, that is, when the MOSFET does not have an overcurrent fault, the voltage corresponding to the detected current flowing through the MOSFET (that is, the output voltage signal of the first amplifier COM1) is less than the preset reference voltage Vref At this time, the second amplifier COM2 outputs a low-level signal to the flip-flop M1, and the inverting output terminal of the flip-flop M1 outputs a high-level signal to the logic AND gate M2. The logic AND gate M2 combines the preset PWM signal (such as a high-level signal) input at its second input terminal, so that the drive signal input to the drive circuit 30 always remains a high-level signal, thereby providing the drive signal required to turn on the MOSFET to the MOSFET, thus realizing the normal operation of the MOSFET. When an overcurrent fault occurs in the MOSFET, the voltage across the first resistor R1 will increase. At this time, the output voltage signal of the first amplifier COM1 will increase, and the output voltage signal of the first amplifier COM1 will be compared with the preset reference voltage V ref If the output voltage signal of the first amplifier COM1 is higher than the preset reference voltage V ref it indicates that an overcurrent fault has occurred in the MOSFET. At this time, the second amplifier COM2 outputs a high-level signal to the flip-flop M1, and the inverting output terminal of the flip-flop M1 outputs a low-level signal to the logic AND gate M2. The logic AND gate M2 combines the preset PWM signal (such as a high-level signal) input at its second input terminal, so that the drive signal input to the drive circuit 30 always remains a low-level signal, thereby providing the drive signal required to turn off the MOSFET to the MOSFET, thus realizing quickly turning off the MOSFET when an overcurrent fault occurs in the MOSFET, and further ensuring the safety of the MOSFET.

[0058] Optionally, the drive circuit is a push-pull drive circuit.

[0059] In addition, the drive circuit can also be other drive circuits, which are not specifically limited here.

[0060] In the technical solution of this embodiment, the implementation process of the MOSFET overcurrent protection circuit is as follows: Refer to Figure 3 , the current detection circuit 10 detects the current flowing through the MOSFET and outputs it to the current-voltage conversion unit 21. The current-voltage conversion unit 21 converts the detected current flowing through the MOSFET into a corresponding voltage according to the received current and outputs it to the voltage comparison unit 22. The voltage comparison unit 22 compares the voltage signal corresponding to the detected current flowing through the MOSFET with the preset reference voltage V ref to determine whether an overcurrent fault has occurred in the MOSFET. Under normal circumstances, that is, when no overcurrent fault occurs in the MOSFET, the output voltage signal of the first amplifier COM1 is less than the preset reference voltage V ref At this time, the second amplifier COM2 outputs a low-level signal to the flip-flop M1, and the inverting output terminal of the flip-flop M1 Output a high-level signal to the logic AND gate M2. The logic AND gate M2 combines the preset PWM signal (such as a high-level signal) input at its second input terminal, so that the drive signal input to the drive circuit 30 always remains a high-level signal, thereby providing the drive signal required to turn on the MOSFET to the MOSFET, and thus realizing the normal operation of the MOSFET. When an overcurrent fault occurs in the MOSFET, the voltage across the first resistor R1 will increase. At this time, the output voltage signal of the first amplifier COM1 will increase, and the output voltage signal of the first amplifier COM1 will be compared with the preset reference voltage V ref for comparison. If the output voltage signal of the first amplifier COM1 is higher than the preset reference voltage V ref it indicates that an overcurrent fault has occurred in the MOSFET. At this time, the second amplifier COM2 will output a high-level signal to the flip-flop M1, and the inverted output terminal of the flip-flop M1 outputs a low-level signal to the logic AND gate M2. The logic AND gate M2 combines the preset PWM signal (such as a high-level signal) input at its second input terminal, so that the drive signal input to the drive circuit 30 always remains a low-level signal, thereby providing the drive signal required to turn off the MOSFET to the MOSFET, and thus realizing quickly turning off the MOSFET when an overcurrent fault occurs in the MOSFET, and further ensuring the safety of the MOSFET. Thus, by detecting the current flowing through the MOSFET, converting it into a corresponding voltage signal and comparing it with the preset reference voltage to determine whether an overcurrent fault has occurred in the MOSFET, the quick detection of whether an overcurrent fault has occurred in the MOSFET is realized, and when it is detected that an overcurrent fault has occurred in the MOSFET, the MOSFET can be quickly turned off in time to protect the safety of the device. Compared with the existing overcurrent protection methods, it has a shorter detection time, and when an overcurrent fault occurs in the MOSFET, the device can be turned off in a shorter time to protect the safe operation of the device and avoid damaging the device.

[0061] An embodiment of the present invention also provides a MOSFET device, which includes the MOSFET overcurrent protection circuit provided in any embodiment of the present invention.

[0062] Since the MOSFET device includes the MOSFET overcurrent protection circuit provided in any embodiment of the present invention, it has the function of detecting overcurrent faults, and when it is detected that an overcurrent fault has occurred, it can quickly turn off the MOSFET device to ensure the safety of the MOSFET device.

[0063] It should be understood that the various forms of processes shown above can be used, with steps reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0064] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A MOSFET overcurrent protection circuit, characterized in that, Including: A first resistor, a current detection circuit, a logic comparison circuit, and a drive circuit; Wherein, the first end of the first resistor is electrically connected to the drain of the MOSFET; the second end of the first resistor is electrically connected to the current detection circuit; the current detection circuit is also electrically connected to the MOSFET and the logic comparison circuit respectively; the logic comparison circuit is also electrically connected to the drive circuit; the drive circuit is also electrically connected to the gate of the MOSFET; Wherein, the current detection circuit is used to detect the current flowing through the MOSFET and output it to the logic comparison circuit; The logic comparison circuit is used to judge whether the MOSFET has an overcurrent fault according to the detected current flowing through the MOSFET, and output a first level signal to the drive circuit when there is no overcurrent fault, or output a second level signal to the drive circuit when there is an overcurrent fault; The drive circuit is used to provide the drive signal required for the MOSFET to turn on or off to the MOSFET according to the first level signal or the second level signal; The current detection circuit includes a diode and a first capacitor; wherein, the anode of the diode is electrically connected to the second end of the first resistor, and the cathode of the diode is electrically connected to the first end of the first capacitor and the logic comparison circuit respectively; the second end of the first capacitor is electrically connected to the drain of the MOSFET, the first end of the first resistor, and the logic comparison circuit respectively.

2. The MOSFET overcurrent protection circuit according to claim 1, wherein The logic comparison circuit includes a current-voltage conversion unit, a voltage comparison unit, and a level signal output unit; wherein, the current-voltage conversion unit is electrically connected to the current detection circuit and the voltage comparison unit respectively; the voltage comparison unit is also electrically connected to the level signal output unit; the level signal output unit is also electrically connected to the drive circuit.

3. The MOSFET overcurrent protection circuit according to claim 2, characterized in that, The current-voltage conversion unit includes a first amplifier and a second capacitor; wherein, the first input terminal and the second input terminal of the first amplifier are both electrically connected to the current detection circuit; the output terminal of the first amplifier is electrically connected to the first end of the second capacitor and the voltage comparison unit respectively; the second end of the second capacitor is grounded.

4. The MOSFET overcurrent protection circuit according to claim 3, characterized in that The current-voltage conversion unit further includes a second resistor; the first end of the second resistor is electrically connected to the current detection circuit and the first input terminal of the first amplifier respectively, and the second end of the second resistor is electrically connected to the output terminal of the first amplifier, the first end of the second capacitor, and the voltage comparison unit respectively.

5. The MOSFET overcurrent protection circuit according to claim 2, characterized in that, The voltage comparison unit includes a second amplifier; the first input terminal of the second amplifier is electrically connected to the current-voltage conversion unit, the second input terminal of the second amplifier is connected to a preset reference voltage; the output terminal of the second amplifier is electrically connected to the level signal output unit.

6. The MOSFET overcurrent protection circuit according to claim 2, wherein The level signal output unit includes a flip-flop and a logic AND gate; wherein, the data input terminal of the flip-flop is grounded, the clock input terminal of the flip-flop is electrically connected to the voltage comparison unit, the inverted output terminal of the flip-flop is electrically connected to the first input terminal of the logic AND gate, and a preset PWM signal is input to the second input terminal of the logic AND gate; the output terminal of the logic AND gate is electrically connected to the drive circuit.

7. The MOSFET overcurrent protection circuit according to claim 1, wherein The drive circuit is a push-pull drive circuit.

8. The MOSFET overcurrent protection circuit according to claim 1, wherein The first level signal is a high-level signal, and the second level signal is a low-level signal.

9. A MOSFET device, characterized in that, It includes the MOSFET overcurrent protection circuit according to any one of claims 1-8.

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