Protection circuit for MOS tube, chip and electronic equipment

Abstract

The utility model provides a protection circuit for an MOS tube, a chip and electronic equipment. The protection circuit comprises a driving signal turn-off circuit and an overcurrent trigger detection circuit. The first end of the driving signal turn-off circuit is connected with a driving signal, the second end is connected with the grid electrode of the MOS tube to be protected, and the third end is connected with the first end of the overcurrent trigger detection circuit; the second end of the overcurrent trigger detection circuit is connected with one end of the MOS tube to be protected; the overcurrent trigger detection circuit generates a protection trigger signal according to the acquired real-time current information and a preset turn-off condition; when the protection trigger signal is a turn-off signal, self-locking is triggered until a reset signal is received; and when the protection trigger signal is a turn-off signal, the signal turn-off circuit is driven to turn off the MOS tube to be protected. The over-current protection circuit can protect the MOS tube to be protected during over-current, has a self-locking function after triggering, and can prevent over-current faults from causing secondary damage to the MOS tube to be protected.

Description

Technical Field

[0001] The utility model relates to the technical field of MOSFET protection, in particular to a protection circuit, a chip and an electronic device for a MOS tube. Background Art

[0002] With the rapid development of semiconductor technology, MOSFET (metal-oxide semiconductor field effect transistor, MOS tube for short) is widely used in various switching power supplies, motor controllers and other power electronic equipment due to its advantages such as high switching frequency, low conduction loss and large input resistance. However, due to the maximum junction temperature limit, the current limit value of the MOS tube has strict requirements. When the current flowing through the MOS tube exceeds the maximum current value of its limit, a great deal of heat will be generated in a short time, causing damage to the MOS tube. In severe cases, the MOS tube will explode and endanger personal safety. Therefore, adding an overcurrent protection circuit to the MOS tube can effectively reduce the damage of the MOS tube during product development and testing, while ensuring the safety of R&D and testing personnel.

[0003] Among the technologies related to MOS tube overcurrent protection, the mainstream solutions are mainly divided into the following two categories:

[0004] One type is to feed back the current signal sampled by ADC (Analog-to-Digital Converter) to the control chip through the current sampling circuit, and the control program determines whether the current value is greater than the current limit of the MOS tube. When the current value is greater than the current limit of the MOS tube, the gate drive signal of the MOS tube is turned off, thereby turning off the MOS tube and reducing the current flowing through the MOS tube to 0, protecting the MOS tube from breakdown and damage. However, research has found that when an overcurrent or short circuit fault occurs in the circuit, the time for generating a large current is usually extremely short. Due to the influence of the current sampling circuit and the program running time, the overcurrent protection determined by the software program cannot respond to the instantaneous large current signal in time, thereby causing damage to the MOS tube.

[0005] The other type uses a pure hardware circuit to determine whether the MOS tube is overcurrent. If the current of the MOS tube exceeds its current limit, the driving signal of the MOS tube is forced to be pulled down, the MOS tube is turned off, and the overcurrent protection function is realized. However, research has found that most pure hardware overcurrent protection circuits can only turn off the MOS tube when the MOS tube is overcurrent. Once the current drops to 0 after the MOS is turned off, the MOS tube will return to the normal conduction state. At this time, if the circuit fault is not resolved, it may cause secondary damage to the circuit. In addition, under high-power conditions, the frequent on and off of the MOS tube with large current will also affect its working performance and service life.

[0006] It should be noted that the information disclosed in the background technology section of the utility model is only intended to deepen the understanding of the general background technology of the utility model, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Utility Model Content

[0007] The present invention aims at one or more technical problems that, when a MOS tube is provided with overcurrent protection, a purely software overcurrent protection scheme has a slow response speed, and a purely hardware overcurrent protection circuit may cause secondary damage to the MOS tube when a circuit fault is not resolved. The present invention provides a protection circuit, a chip and an electronic device for the MOS tube. The protection circuit provided by the present invention can ensure the response speed of the circuit relative to the overcurrent protection scheme controlled by a software program; and the present invention has a self-locking function after being triggered, which can prevent the overcurrent fault from causing secondary damage to the MOS tube after the overcurrent fault occurs. Furthermore, the present invention has a simple circuit structure and is easy to implement.

[0008] To achieve the above-mentioned purpose, the utility model is implemented by the following technical solutions: a protection circuit for a MOS tube, the protection circuit comprising a drive signal shutdown circuit and an overcurrent trigger detection circuit; the first end of the drive signal shutdown circuit is configured to access the drive signal, the second end of the drive signal shutdown circuit is connected to the gate of the MOS tube to be protected, and the third end of the drive signal shutdown circuit is connected to the first end of the overcurrent trigger detection circuit to receive the protection trigger signal; the second end of the overcurrent trigger detection circuit is connected to one end of the MOS tube to be protected to obtain the real-time current information of the MOS tube to be protected;

[0009] The overcurrent trigger detection circuit is configured to generate the protection trigger signal according to the real-time current information and the preset shutdown condition; and trigger self-locking when the protection trigger signal is a shutdown signal until a reset signal is received; the drive signal shutdown circuit is configured to shut down the MOS tube to be protected when the protection trigger signal is the shutdown signal.

[0010] Optionally, the drive signal shutdown circuit includes a drive transistor, a first resistor and a second resistor; a common point between the first end of the drive transistor and the first end of the first resistor is configured to access the drive signal; the second end of the first resistor is connected to the gate of the MOS tube to be protected; the first end of the second resistor is connected to the first end of the overcurrent trigger detection circuit to receive a protection trigger signal; the second end of the second resistor is connected to the gate of the drive transistor, and the second end of the gate of the drive transistor is grounded;

[0011] The drive signal shutoff circuit is configured to turn on the drive transistor when the protection trigger signal is at a high level, thereby lowering the voltage at the second end of the first resistor to shut off the MOS tube to be protected.

[0012] Optionally, the overcurrent trigger detection circuit includes an overcurrent signal detection circuit and an overcurrent trigger circuit, the first end of the overcurrent signal detection circuit is connected to one end of the MOS tube to be protected to obtain the real-time current information, the second end of the overcurrent signal detection circuit is configured to access a first power supply voltage, the third end of the overcurrent signal detection circuit is grounded, and the fourth end of the overcurrent signal detection circuit is connected to the second end of the overcurrent trigger circuit;

[0013] The overcurrent signal detection circuit is configured to generate a detection result signal based on the real-time current information and a preset shutdown condition; the overcurrent trigger circuit is configured to generate the protection trigger signal based on the detection result signal; and set the protection trigger signal to a high level when the detection result signal is at a low level, and trigger self-locking when the protection trigger signal is at a high level until the reset signal is received.

[0014] Optionally, the overcurrent signal detection circuit includes a third resistor, a fourth resistor, a comparator and a reference voltage generating circuit; the common point of the first end of the third resistor and the first end of the fourth resistor is connected to one end of the MOS tube to be protected to obtain the real-time current information; the second end of the third resistor is grounded; the second end of the fourth resistor is connected to the first input end of the comparator, and the second input end of the comparator is connected to the output end of the reference voltage generating circuit; the output end of the comparator is connected to the second end of the overcurrent trigger circuit.

[0015] Optionally, the reference voltage generating circuit includes a fifth resistor, a sixth resistor and a seventh resistor, the first end of the fifth resistor is configured to be connected to a first supply voltage, the second end of the fifth resistor, the first end of the sixth resistor and the first end of the seventh resistor are connected in common, the second end of the sixth resistor is grounded, and the second end of the seventh resistor is connected to the second input terminal of the comparator.

[0016] Optionally, the overcurrent trigger circuit includes an RS trigger, a delay circuit and an eighth resistor, the output end of the RS trigger is connected to the third end of the drive signal shutdown circuit, the reset end of the RS trigger is connected to the output end of the delay circuit, and the set end of the RS trigger is connected in series with the eighth resistor and then connected to the fourth end of the overcurrent signal detection circuit;

[0017] The RS trigger is configured to generate the protection trigger signal according to the detection result signal; and to set the protection trigger signal to a high level when the detection result signal is at a low level, and to trigger self-locking when the protection trigger signal is at a high level until the reset signal is received;

[0018] The reset signal includes powering off the delay circuit and then powering it on again, or using an external reset signal to trigger.

[0019] Optionally, the RS trigger comprises an AND-NOR gate RS trigger.

[0020] Optionally, the delay circuit includes a ninth resistor and a capacitor, the first end of the ninth resistor is configured to be connected to a second supply voltage, the common point between the second end of the ninth resistor and the first end of the capacitor is connected to the reset end of the RS trigger, and the second end of the capacitor is grounded.

[0021] Optionally, a third terminal of the overcurrent trigger detection circuit is used to access a power supply voltage, and a fourth terminal of the overcurrent trigger detection circuit is grounded.

[0022] In order to achieve the above object, the utility model further provides a chip, on which any of the protection circuits described above is integrated.

[0023] In order to achieve the above-mentioned purpose, the utility model also provides an electronic device, which includes a driving chip, at least one MOS tube to be protected, and any one of the above-mentioned protection circuits for the MOS tube or the above-mentioned chips; the driving chip, the MOS tube to be protected and the protection circuit are coupled; the driving chip is configured to send a driving signal to the MOS tube to be protected; the protection circuit is configured to turn off the MOS tube to be protected when the MOS tube to be protected is overcurrent until a reset signal is received.

[0024] Compared with the prior art, the protection circuit, chip and electronic device for MOS tube provided by the utility model have the following beneficial effects:

[0025] The utility model provides a protection circuit for a MOS tube, comprising a drive signal shutdown circuit and an overcurrent trigger detection circuit; the first end of the drive signal shutdown circuit is configured to access a drive signal, the second end of the drive signal shutdown circuit is connected to the gate of the MOS tube to be protected, and the third end of the drive signal shutdown circuit is connected to the first end of the overcurrent trigger detection circuit to receive a protection trigger signal; the second end of the overcurrent trigger detection circuit is connected to one end of the MOS tube to be protected to obtain real-time current information of the MOS tube to be protected; the overcurrent trigger detection circuit is configured to generate the protection trigger signal according to the real-time current information and a preset shutdown condition; and trigger self-locking when the protection trigger signal is a shutdown signal until a reset signal is received; the drive signal shutdown circuit is configured to shut down the MOS tube to be protected when the protection trigger signal is the shutdown signal. It can be seen that the overcurrent trigger detection circuit for the protection circuit of the MOS tube provided by the utility model can generate the protection trigger signal according to the real-time current information of the MOS tube to be protected and the preset shutdown condition; and trigger self-locking until receiving a reset signal when the protection trigger signal is a shutdown signal; the drive signal shutdown circuit is configured to shut down the MOS tube to be protected when the protection trigger signal is the shutdown signal. With such a configuration, the utility model is implemented by a pure hardware circuit, which can ensure the response speed of the circuit compared to the overcurrent protection scheme controlled by the software program; and the utility model has a self-locking function after triggering, which can avoid the overcurrent fault from causing secondary damage to the MOS tube after the overcurrent fault occurs. Furthermore, the circuit structure of the utility model is simple, easy to implement, and can significantly reduce the application cost of the protection circuit.

[0026] Since the chip and electronic device provided by the utility model and the protection circuit for the MOS tube provided by the utility model belong to the same utility model concept, the chip and electronic device provided by the utility model at least have all the beneficial effects of the protection circuit for the MOS tube provided by the utility model. For details, please refer to the relevant description of the beneficial effects of the protection circuit for the MOS tube provided by the utility model in the above text, so the beneficial effects of the chip and electronic device provided by the utility model will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A structural block diagram of a protection circuit for a MOS tube provided in the first embodiment of the utility model;

[0028] Figure 2 A circuit structure diagram of a specific example of a protection circuit for a MOS tube provided in the first embodiment of the utility model;

[0029] Figure 3A circuit structure diagram of another specific example of a protection circuit for a MOS tube provided in the first embodiment of the utility model;

[0030] Figure 4 A timing diagram of a specific example of a protection circuit for a MOS tube provided in the first embodiment of the utility model;

[0031] The reference numerals are described as follows:

[0032] MOS tube to be protected - Q1;

[0033] Driving signal shutoff circuit-110, driving transistor-Q2, first resistor-R1, second resistor-R2;

[0034] Overcurrent trigger detection circuit-120, first power supply voltage-VCC1, second power supply voltage-VCC2;

[0035] Overcurrent signal detection circuit-121, third resistor-R3, fourth resistor-R4, comparator-COMP, reference voltage generation circuit-U1, fifth resistor-R5, sixth resistor-R6, seventh resistor-R7;

[0036] Overcurrent trigger circuit-122, RS trigger-U2, output terminal-Q, reset terminal- Set terminal - Eighth resistor-R8, delay circuit-RC, ninth resistor-R9, capacitor-C;

[0037] Protection circuit-100, driving chip-200. DETAILED DESCRIPTION

[0038] In order to make the purpose, advantages and features of the utility model clearer, the protection circuit, chip and electronic device for MOS tube proposed by the utility model are further described in detail below in conjunction with the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiment of the utility model. It should be understood that the drawings in the specification do not necessarily show the specific structure of the utility model in proportion, and the illustrative features used to illustrate certain principles of the utility model in the drawings in the specification will also adopt a slightly simplified drawing method. The specific design features of the utility model disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or a part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. Where appropriate, these terms used in this way are interchangeable.

[0039] It should be understood that when an element is referred to as being "connected," "connected to," or "coupled to" another element, it can be directly connected to the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly connected to" another element, there are no intervening elements.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] The first embodiment of the utility model provides a protection circuit for a MOS tube. Specifically, see Figure 1 , Figure 1 FIG. 1 is a structural block diagram of the protection circuit for MOS tube in this embodiment. Figure 1It can be seen that the protection circuit includes a drive signal shutdown circuit 110 and an overcurrent trigger detection circuit 120. Specifically, the first end of the drive signal shutdown circuit 110 is configured to access the drive signal, the second end of the drive signal shutdown circuit 110 is connected to the gate of the MOS tube Q1 to be protected, and the third end of the drive signal shutdown circuit 110 is connected to the first end of the overcurrent trigger detection circuit 120 to receive the protection trigger signal; the second end of the overcurrent trigger detection circuit 120 is connected to one end of the MOS tube Q1 to be protected to obtain the real-time current information of the MOS tube Q1 to be protected. The overcurrent trigger detection circuit 120 is configured to generate the protection trigger signal according to the real-time current information and the preset shutdown condition; and trigger self-locking when the protection trigger signal is a shutdown signal until a reset signal is received; the drive signal shutdown circuit 110 is configured to shut down the MOS tube Q1 to be protected when the protection trigger signal is the shutdown signal.

[0042] It can be seen that the overcurrent trigger detection circuit 120 for the protection circuit of the MOS tube provided by the utility model can generate the protection trigger signal according to the real-time current information of the MOS tube Q1 to be protected and the preset shutdown condition; and trigger self-locking until receiving a reset signal when the protection trigger signal is a shutdown signal; the drive signal shutdown circuit 110 is configured to shut down the MOS tube Q1 to be protected when the protection trigger signal is the shutdown signal. With such a configuration, the utility model is implemented by a pure hardware circuit, which can ensure the response speed of the circuit compared to the overcurrent protection scheme controlled by the software program; and the utility model has a self-locking function after triggering, which can avoid the overcurrent fault from causing secondary damage to the MOS tube after the overcurrent fault occurs. Further, the circuit structure of the utility model is simple, easy to implement, and can significantly reduce the application cost of the protection circuit.

[0043] It should be noted that those skilled in the art should be able to understand that the utility model does not limit the source of the drive signal. For example, in some embodiments, the drive signal may come from the driver chip 200; in other embodiments, the drive signal may also come from the circuit system where the MOS tube Q1 to be protected is located. Furthermore, the utility model does not limit the drive signal, and the drive signal may be, but is not limited to, a PWM (Pulse-width modulation) signal, a PFM mode (Pulse frequency modulation), and an automatic mode (Auto-mode), etc.

[0044] Specifically, the protection trigger signal is generated according to the real-time current information of the MOS tube Q1 to be protected and the preset shutdown condition, including: when the real-time current value flowing through the MOS tube Q1 to be protected exceeds the preset overcurrent threshold, the protection trigger signal is set to a shutdown signal (for example, a high level indicates a shutdown signal).

[0045] Please continue to see Figure 2 , Figure 2 FIG. 1 is a circuit diagram of a specific example of a protection circuit for a MOS tube provided in this embodiment. Figure 2 It can be seen that the driving signal shutdown circuit 110 includes a driving transistor Q2, a first resistor R1 and a second resistor R2; the common point of the first end of the driving transistor Q2 and the first end of the first resistor R1 is configured to access the driving signal; the second end of the first resistor R1 is connected to the gate of the MOS tube Q1 to be protected; the first end of the second resistor R2 is connected to the first end of the overcurrent trigger detection circuit 120 to receive the protection trigger signal; the second end of the second resistor R2 is connected to the gate of the driving transistor Q2, and the second end of the gate of the driving transistor Q2 is grounded. Specifically, the driving signal shutdown circuit 110 is configured to turn on the driving transistor Q2 when the protection trigger signal is at a high level, thereby lowering the voltage of the second end of the first resistor R1 to turn off the MOS tube Q1 to be protected.

[0046] Configured in this way, the protection circuit for the MOS tube provided by the utility model, the drive signal shutdown circuit 110 only includes the drive transistor Q2, the first resistor R1 and the second resistor R2. It not only has clear logic, requires fewer circuit components, has a simple circuit structure, is easy to implement, but also can reduce the application cost of the protection circuit.

[0047] Exemplarily, the driving transistor Q2 may be an NPN transistor. It should be noted that those skilled in the art should be able to understand that the present invention does not impose too many restrictions on the driving transistor Q2, as long as it can pull down the voltage at the second end of the first resistor R1 to turn off the MOS transistor Q1 to be protected when the protection trigger signal is at a high level. Exemplarily, in other embodiments, the driving transistor Q2 may be, but is not limited to, a transistor or a MOSFET. For example, the driving transistor Q2 may be a PNP transistor.

[0048] Preferably, the third terminal of the overcurrent trigger detection circuit 120 is used to access the power supply voltage, and the fourth terminal of the overcurrent trigger detection circuit 120 is grounded. In this way, an independent power supply voltage is used to power the overcurrent trigger detection circuit 120, further improving the reliability of the protection circuit provided by the utility model.

[0049] In some exemplary embodiments, please continue to see Figure 2 ,from Figure 2 It can be seen that the overcurrent trigger detection circuit 120 includes an overcurrent signal detection circuit 121 and an overcurrent trigger circuit 122. Specifically, the first end of the overcurrent signal detection circuit 121 is connected to one end of the MOS tube Q1 to be protected to obtain the real-time current information, the second end of the overcurrent signal detection circuit 121 is configured to access the first power supply voltage VCC1, the third end of the overcurrent signal detection circuit 121 is grounded, and the fourth end of the overcurrent signal detection circuit 121 is connected to the second end of the overcurrent trigger circuit 122. More specifically, the overcurrent signal detection circuit 121 is configured to generate a detection result signal according to the real-time current information and the preset shutdown condition; the overcurrent trigger circuit 122 is configured to generate the protection trigger signal according to the detection result signal; and when the detection result signal is at a low level, the protection trigger signal is set to a high level, and when the protection trigger signal is at a high level, the self-locking is triggered until the reset signal is received.

[0050] It can be seen that the protection circuit for MOS tube provided by the utility model, the overcurrent trigger detection circuit 120 includes an overcurrent signal detection circuit 121 and an overcurrent trigger circuit 122. This modular design method is not only simple in structure and clear in logic, but also easy to implement. Furthermore, the overcurrent signal detection circuit 121 can generate a detection result signal according to the real-time current information and the preset shutdown condition; the overcurrent trigger circuit 122 can generate the protection trigger signal according to the detection result signal; and when the detection result signal is at a low level, the protection trigger signal is set to a high level, and when the protection trigger signal is at a high level, the self-locking is triggered until the reset signal is received (such as the overcurrent fault is resolved). With such a setting, when an overcurrent fault occurs, the MOS tube Q1 to be protected can be kept in a closed state, thereby avoiding secondary damage to the MOS tube Q1 to be protected caused by the overcurrent fault.

[0051] In some exemplary embodiments, see Figure 3 , Figure 3 FIG. 1 is a circuit diagram of another specific example of a protection circuit for a MOS tube provided in this embodiment. Figure 3It can be seen that the overcurrent signal detection circuit 121 includes a third resistor R3, a fourth resistor R4, a comparator COMP and a reference voltage generating circuit U1; the common point of the first end of the third resistor R3 and the first end of the fourth resistor R4 is connected to one end of the MOS tube Q1 to be protected to obtain the real-time current information; the second end of the third resistor R3 is grounded; the second end of the fourth resistor R4 is connected to the first input end of the comparator COMP, and the second input end of the comparator COMP is connected to the output end of the reference voltage generating circuit U1; the output end of the comparator COMP is connected to the second end of the overcurrent trigger circuit 122.

[0052] Therefore, with such configuration, the protection circuit for the MOS tube provided by the utility model, the overcurrent signal detection circuit 121 only includes the third resistor R3, the fourth resistor R4, the comparator COMP and the reference voltage generating circuit U1, not only fewer electronic components are required, but also the resistor device and the comparator COMP are inexpensive and easy to obtain, which can significantly reduce the cost of the protection circuit.

[0053] In some exemplary embodiments, please continue to see Figure 3 The reference voltage generating circuit U1 includes a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, the first end of the fifth resistor R5 is configured to be connected to the first power supply voltage VCC1, the second end of the fifth resistor R5, the first end of the sixth resistor R6 and the first end of the seventh resistor R7 are connected in common, the second end of the sixth resistor R6 is grounded, and the second end of the seventh resistor R7 is connected to the second input end of the comparator COMP.

[0054] Therefore, with such configuration, the protection circuit for the MOS tube provided by the utility model, the reference voltage generating circuit U1 includes a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, and the resistor devices are inexpensive and easy to obtain, which can significantly reduce the cost of the protection circuit; further, the resistance values ​​of the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 can be reasonably selected according to actual needs to generate the required reference voltage.

[0055] It should be noted that those skilled in the art should be able to understand that the reference voltage generating circuit U1 described in this embodiment includes the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7, which is only an exemplary description of a preferred embodiment, and is not a limitation of the present invention. In other embodiments, other solutions known to those skilled in the art may also be adopted, including but not limited to a voltage stabilizer.

[0056] In some exemplary embodiments, please continue to see Figure 3The overcurrent trigger circuit 122 includes an RS trigger U2, a delay circuit RC, and an eighth resistor R8. Specifically, the output terminal Q of the RS trigger U2 is connected to the third terminal of the drive signal shutdown circuit 110, and the reset terminal of the RS trigger U2 is connected to the reset terminal of the RS trigger U2. Connect the output end of the delay circuit RC and the set end of the RS trigger U2 The eighth resistor R8 is connected in series to the fourth end of the overcurrent signal detection circuit 121. More specifically, the RS trigger U2 is configured to generate the protection trigger signal according to the detection result signal; and to set the protection trigger signal to a high level when the detection result signal is at a low level, and to trigger self-locking when the protection trigger signal is at a high level until the reset signal is received; wherein the reset signal includes powering off the delay circuit RC and then powering it on again, or using an external reset signal trigger (such as including but not limited to triggering through the driver chip 200).

[0057] Therefore, with such configuration, the protection circuit provided by the utility model fully utilizes the working principle of the RS trigger U2 to realize the self-locking function, so that the MOS tube Q1 to be protected is protected.

[0058] Preferably, the RS trigger U2 comprises an AND-NOR gate RS trigger.

[0059] Preferably, in some of the exemplary embodiments, please continue to refer to Figure 3 The delay circuit RC includes a ninth resistor R9 and a capacitor C, wherein the first end of the ninth resistor R9 is configured to be connected to the second power supply voltage VCC2, and the common point of the second end of the ninth resistor R9 and the first end of the capacitor C is connected to the reset end of the RS trigger U2. The second end of the capacitor C is grounded. Therefore, in such a configuration, the protection circuit provided by the utility model, the delay circuit RC only includes the ninth resistor R9 and the capacitor C, which is not only easy to implement, but also can significantly reduce the cost of the protection circuit. It should be noted that the utility model does not limit the specific values ​​of the first power supply voltage VCC1 and the second power supply voltage VCC2, and the voltage values ​​of the first power supply voltage VCC1 and the second power supply voltage VCC2 can be the same or different.

[0060] For a better understanding of the present invention, please refer to Figure 3 and Figure 4 ,in, Figure 4 This is a timing diagram of a specific example of a protection circuit for a MOS tube provided in this embodiment. Figure 3 , Figure 4The working state of the circuit system where the MOS tube Q1 to be protected is located is briefly described as follows for the working sequence of the protection circuit for the MOS tube provided by the utility model.

[0061] It should be noted that, although those skilled in the art should be aware of the working principle of the RS trigger U2 according to the relevant technology, in order to facilitate the understanding of the present invention, Figure 3 The truth table of the RS flip-flop U2 is as follows:

[0062] Truth table of RS flip-flop U2:

[0063]

[0064] In the truth table of RS flip-flop U2, Q n Indicates the original state of RS flip-flop U2, Q n+1 Indicates the next state of RS flip-flop U2.

[0065] (1) When the circuit where the MOS transistor Q1 to be protected is located works normally: the real-time current information flowing through the MOS transistor Q1 to be protected is converted by the third resistor R3 (for example, the voltage at the common point of the third resistor R3 and the fourth resistor R4 is obtained), and the comparator COMP compares the current information with the threshold reference voltage of the reference voltage generating circuit. The threshold reference voltage can be set by adjusting the values ​​of the fifth resistor R5 and the sixth resistor R6. The calculation formula of the threshold reference voltage is as follows:

[0066]

[0067] In formula (1), V ref is the threshold reference voltage, V cc is the voltage value of the first power supply voltage, R5 is the resistance value of the fifth resistor, and R6 is the resistance value of the sixth resistor. When the voltage sampling value corresponding to the real-time current is less than the set threshold reference voltage, the output level of the comparator COMP is high. The comparison result is used as a trigger signal of the overcurrent trigger circuit 122. According to the working principle of the RS trigger U2 trigger U2 (please refer to the truth table of the RS trigger U2 trigger U2 above), the output terminal Q of the RS trigger U2 trigger U2 is low, so the driving transistor Q2 is in the off state, and the gate of the driving transistor Q2 can still normally receive the driving signal provided by the driving chip 200, and the MOS tube Q1 to be protected works normally.

[0068] (2) When an overcurrent fault occurs in the circuit where the MOS transistor Q1 to be protected is located: due to the increase in the current flowing through the MOS transistor Q1 to be protected, when the voltage sampling value corresponding to the real-time current (obtained by conversion by the third resistor R3, in fact, the third resistor R3 is a sampling resistor) is greater than the set threshold reference voltage, the output terminal Q of the comparator COMP outputs a low level and acts on the set terminal of the RS trigger U2. When the RS flip-flop U2 is set Low level, reset terminal When the level is high, the level of the output terminal Q is high. The overcurrent trigger circuit 122 outputs a high level to turn on the driving transistor Q2 in the driving signal shutdown circuit 110, and the driving signal output by the driving chip 200 is grounded, the output signal is forced to be pulled low, and the MOS transistor Q1 to be protected is turned off, thereby avoiding damage to the MOS transistor Q1 to be protected due to long-term exposure to large current.

[0069] (3) After the overcurrent protection of the MOS tube Q1 to be protected is triggered and before the protection trigger signal receives a reset signal: the MOS tube Q1 to be protected is turned off, the current flowing through the third resistor R3 is 0A, and the output of the comparator COMP returns to a high level and is input to the set terminal of the RS trigger U2. At this time, the reset terminal of RS trigger U2 The RS trigger U2 remains at a high level, and the RS trigger U2 will maintain the previous state unchanged (see the truth table of the RS trigger U2 above). Therefore, the output terminal Q of the RS trigger U2 is still at a high level, and the driving transistor Q2 remains on to force the gate driving signal of the MOS tube Q1 to be protected to be pulled low, so that the MOS tube Q1 to be protected can still remain in the off state, and the MOS tube Q1 to be protected will not be damaged due to repeated conduction before the overcurrent problem is solved.

[0070] (4) When the circuit where the MOS tube Q1 to be protected is powered on again after power failure: the set terminal of the RS trigger U2 Will output high level, reset terminal Due to the effect of the delay circuit RC, it will remain at a low level for a period of time after power-on. According to the working principle of the RS trigger U2, the output terminal Q of the RS trigger U2 is reset to a low level, and the gate of the MOS transistor Q1 to be protected can normally receive the driving signal output by the driving chip 200, and the MOS transistor Q1 to be protected works normally.

[0071] A second embodiment of the present invention provides a chip, on which a protection circuit as described in any implementation manner of the first embodiment of the present invention is integrated.

[0072] The protection circuit of the aforementioned embodiment of the present invention can be implemented as a PCB circuit (i.e., discrete components); in addition, other embodiments of the present invention provide a chip, which integrates the protection circuit of the aforementioned embodiment of the present invention, that is, in addition to the aforementioned discrete component implementation, the aforementioned protection circuit can also be implemented as a circuit in a package outside the die of the chip; if the process conditions permit, the aforementioned protection circuit can also be implemented as an integrated circuit inside the die of the chip. However, it should be understood that the present invention does not impose any limitation on the specific existence form of the protection circuit of the aforementioned embodiment.

[0073] It should be noted that those skilled in the art should be able to understand that the present invention does not impose any limitations on the process, application field and function of the chip. For example, the chip may be but not limited to a 7nm chip, a 14nm chip and a 28nm chip; the chip may be but not limited to automotive chips, consumer electronics chips and medical chips, etc.; the chip may be but not limited to a processor chip, a sensor chip and a communication chip, etc.

[0074] The third embodiment of the utility model provides an electronic device. Specifically, the electronic device provided by this embodiment includes a driver chip and at least one MOS tube to be protected. More specifically, the electronic device provided by the first embodiment of this embodiment also includes the protection circuit for the MOS tube described in any implementation of the first embodiment of the utility model; the electronic device provided by the second implementation of this embodiment also includes the chip provided by the second embodiment of the utility model. Furthermore, the driver chip, the MOS tube to be protected and the protection circuit are coupled; the driver chip is configured to send a drive signal to the MOS tube to be protected; the protection circuit is configured to turn off the MOS tube to be protected when the MOS tube to be protected is overcurrent until a reset signal is received.

[0075] Since the chip and electronic device provided by the utility model and the protection circuit for the MOS tube provided by the utility model belong to the same utility model concept, the chip and electronic device provided by the utility model at least have all the beneficial effects of the protection circuit for the MOS tube provided by the utility model. For details, please refer to the relevant description of the beneficial effects of the protection circuit for the MOS tube provided by the utility model in the above text, so the beneficial effects of the chip and electronic device provided by the utility model will not be described one by one here.

[0076] Specifically, it should be noted that those skilled in the art should be able to understand that the present utility model does not impose any limitation on the electronic equipment. For example, the electronic equipment includes but is not limited to video products such as televisions, video recorders, and digital cameras, communication products such as mobile phones, communication switching equipment, and communication transmission equipment, learning assistance products such as translators, learning machines, and electronic dictionaries, and medical equipment products such as medical imaging equipment and medical testing equipment, etc., without giving examples one by one.

[0077] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0078] Compared with the prior art, the protection circuit, chip and electronic device for MOS tube provided by the utility model have the following beneficial effects:

[0079] The overcurrent trigger detection circuit for the protection circuit of the MOS tube provided by the utility model can generate the protection trigger signal according to the real-time current information of the MOS tube to be protected and the preset shutdown condition; and trigger self-locking until receiving a reset signal when the protection trigger signal is a shutdown signal; the drive signal shutdown circuit is configured to shut down the MOS tube to be protected when the protection trigger signal is the shutdown signal. With such a configuration, the utility model is implemented by a pure hardware circuit, which can ensure the response speed of the circuit compared to the overcurrent protection scheme controlled by the software program; and the utility model has a self-locking function after triggering, which can avoid the overcurrent fault from causing secondary damage to the MOS tube after the overcurrent fault occurs. Furthermore, the circuit structure of the utility model is simple, easy to implement, and can significantly reduce the application cost of the protection circuit.

[0080] Since the chip and electronic device provided by the utility model and the protection circuit for the MOS tube provided by the utility model belong to the same utility model concept, the chip and electronic device provided by the utility model at least have all the beneficial effects of the protection circuit for the MOS tube provided by the utility model. For details, please refer to the relevant description of the beneficial effects of the protection circuit for the MOS tube provided by the utility model in the above text, so the beneficial effects of the chip and electronic device provided by the utility model will not be described one by one here.

[0081] In summary, the above embodiments provide a detailed description of different configurations of protection circuits, chips and electronic devices for MOS tubes provided by the utility model. Of course, the above description is only a description of the preferred embodiments of the utility model, and is not any limitation on the scope of the utility model. The utility model includes but is not limited to the configurations listed in the above implementations. Those skilled in the art can draw inferences based on the contents of the above embodiments. Any changes and modifications made by ordinary technicians in the field of the utility model based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A protection circuit for MOS tube, It is characterized in that The protection circuit includes a drive signal shutdown circuit and an overcurrent trigger detection circuit; the first end of the drive signal shutdown circuit is configured to access the drive signal, the second end of the drive signal shutdown circuit is connected to the gate of the MOS tube to be protected, and the third end of the drive signal shutdown circuit is connected to the first end of the overcurrent trigger detection circuit to receive the protection trigger signal; the second end of the overcurrent trigger detection circuit is connected to one end of the MOS tube to be protected to obtain real-time current information of the MOS tube to be protected; The overcurrent trigger detection circuit is configured to generate the protection trigger signal according to the real-time current information and the preset shutdown condition; And when the protection trigger signal is a shutdown signal, self-locking is triggered until a reset signal is received; the drive signal shutdown circuit is configured to shut down the MOS tube to be protected when the protection trigger signal is the shutdown signal.

2. The protection circuit according to claim 1, It is characterized in that The driving signal shutoff circuit comprises a driving transistor, a first resistor and a second resistor; a common point of the first end of the driving transistor and the first end of the first resistor is configured to access the driving signal; The second end of the first resistor is connected to the gate of the MOS tube to be protected; the first end of the second resistor is connected to the first end of the overcurrent trigger detection circuit to receive a protection trigger signal; the second end of the second resistor is connected to the gate of the driving transistor, and the second end of the gate of the driving transistor is grounded; The drive signal shutoff circuit is configured to turn on the drive transistor when the protection trigger signal is at a high level, thereby lowering the voltage at the second end of the first resistor to shut off the MOS tube to be protected.

3. The protection circuit according to claim 1, It is characterized in that The overcurrent trigger detection circuit comprises an overcurrent signal detection circuit and an overcurrent trigger circuit, wherein a first end of the overcurrent signal detection circuit is connected to one end of the MOS tube to be protected to obtain the real-time current information, a second end of the overcurrent signal detection circuit is configured to access a first power supply voltage, a third end of the overcurrent signal detection circuit is grounded, and a fourth end of the overcurrent signal detection circuit is connected to the second end of the overcurrent trigger circuit; The overcurrent signal detection circuit is configured to generate a detection result signal according to the real-time current information and a preset shutdown condition; The overcurrent trigger circuit is configured to generate the protection trigger signal according to the detection result signal; and set the protection trigger signal to a high level when the detection result signal is at a low level, and trigger self-locking when the protection trigger signal is at a high level until the reset signal is received.

4. The protection circuit according to claim 3, It is characterized in that The overcurrent signal detection circuit includes a third resistor, a fourth resistor, a comparator and a reference voltage generating circuit; the common point of the first end of the third resistor and the first end of the fourth resistor is connected to one end of the MOS tube to be protected to obtain the real-time current information; the second end of the third resistor is grounded; the second end of the fourth resistor is connected to the first input end of the comparator, and the second input end of the comparator is connected to the output end of the reference voltage generating circuit; the output end of the comparator is connected to the second end of the overcurrent trigger circuit.

5. The protection circuit according to claim 4, It is characterized in that The reference voltage generating circuit includes a fifth resistor, a sixth resistor and a seventh resistor, the first end of the fifth resistor is configured to be connected to a first supply voltage, the second end of the fifth resistor, the first end of the sixth resistor and the first end of the seventh resistor are connected in common, the second end of the sixth resistor is grounded, and the second end of the seventh resistor is connected to the second input terminal of the comparator.

6. The protection circuit according to claim 3, It is characterized in that The overcurrent trigger circuit includes an RS trigger, a delay circuit and an eighth resistor, the output end of the RS trigger is connected to the third end of the drive signal shutdown circuit, the reset end of the RS trigger is connected to the output end of the delay circuit, and the set end of the RS trigger is connected in series with the eighth resistor and then connected to the fourth end of the overcurrent signal detection circuit; The RS trigger is configured to generate the protection trigger signal according to the detection result signal; and to set the protection trigger signal to a high level when the detection result signal is at a low level, and to trigger self-locking when the protection trigger signal is at a high level until the reset signal is received; The reset signal includes powering off the delay circuit and then powering it on again, or using an external reset signal to trigger.

7. The protection circuit according to claim 6, It is characterized in that The RS trigger comprises an AND-NOR gate RS trigger.

8. The protection circuit according to claim 6, It is characterized in that The delay circuit includes a ninth resistor and a capacitor, the first end of the ninth resistor is configured to be connected to a second power supply voltage, the common point of the second end of the ninth resistor and the first end of the capacitor is connected to the reset end of the RS trigger, and the second end of the capacitor is grounded.

9. The protection circuit according to claim 1, It is characterized in that The third terminal of the overcurrent trigger detection circuit is used to access the power supply voltage, and the fourth terminal of the overcurrent trigger detection circuit is grounded.

10. A chip, It is characterized in that The chip is integrated with the protection circuit as claimed in any one of claims 1 to 9.

11. An electronic device, comprising a driver chip and at least one MOS tube to be protected; It is characterized in that The electronic device also includes a protection circuit for a MOS tube as described in any one of claims 1 to 9 or a chip as described in claim 10; the driving chip, the MOS tube to be protected and the protection circuit are coupled; the driving chip is configured to send a driving signal to the MOS tube to be protected; the protection circuit is configured to turn off the MOS tube to be protected when the MOS tube to be protected is overcurrent until a reset signal is received.

Images