Driving protection circuit of driving chip

Abstract

The utility model provides a driving protection circuit of a driving chip. A short circuit desaturation detection pin of the driving chip is connected with a first end of a power switch unit through an intermediate circuit; a pulse width modulation output pin and a soft turn-off pin of the driving chip are connected with a first input end and a second input end of the push-pull circuit; when the push-pull circuit receives a control signal of a driving chip as a first signal, the push-pull circuit adopts a positive power supply to supply power, and when the push-pull circuit receives a control signal as a second signal, the push-pull circuit adopts a negative power supply to supply power; the output end of the push-pull circuit is connected with the control end of the power switch unit through the driving circuit; namely, when the power switch unit has a fault, the soft turn-off pin of the driving chip does not need to discharge the control end of the power switch unit, but discharges through the power switch unit, so that the soft turn-off pin is prevented from being damaged by over-high current of the control end of the power switch unit, and the driving chip is protected.

Description

Technical Field

[0001] This utility model belongs to the field of power electronics technology, and more specifically, it relates to a drive protection circuit for a drive chip. Background Technology

[0002] In power electronic systems, parallel power switching devices are widely used to improve the system's power handling capacity and reliability. However, due to differences in device parameters and uneven temperature distribution, uneven current distribution often occurs among power switching devices operating in parallel. This not only reduces system efficiency but may also cause individual devices to overheat, thereby shortening equipment lifespan or even causing failures.

[0003] To address the aforementioned issues, patent document CN115765405A discloses a dynamic current sharing control method for parallel power switching devices. The core of this method lies in installing current sensors on each branch of the parallel power switching devices. When the power switching devices are turned on, these sensors can capture the current amplitude information flowing through their respective branches in real time. Based on this information, the system can further analyze and deduce the current magnitude relationship between the branches of each power switching device.

[0004] However, while existing dynamic current sharing control methods for parallel power switching devices have solved the problem of uneven current distribution to some extent, they cannot achieve circuit protection, leading to instability of the driver chip. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a drive protection circuit for a driver chip, which, when a power switch unit malfunctions, allows the soft-shutdown pin of the driver chip to discharge through the power switch unit instead of the control terminal of the power switch unit, thus preventing excessive current at the control terminal of the power switch unit from damaging the soft-shutdown pin and protecting the driver chip.

[0006] This application discloses a drive protection circuit for a driver chip, including: a push-pull circuit, a drive circuit, and a power switching unit;

[0007] The short-circuit desaturation detection pin of the driver chip is connected to the first terminal of the power switch unit through an intermediate circuit;

[0008] The second terminal of the power switch unit is grounded;

[0009] The pulse width modulation output pin of the driver chip is connected to the first input terminal of the push-pull circuit;

[0010] The soft-shutdown pin of the driver chip is connected to the second input terminal of the push-pull circuit;

[0011] The positive and negative terminals of the push-pull circuit are connected to a positive power supply and a negative power supply, respectively. When the push-pull circuit receives a first control signal from the driver chip, the push-pull circuit is powered by the positive power supply. When the push-pull circuit receives a second control signal, the push-pull circuit is powered by the negative power supply.

[0012] The output terminal of the push-pull circuit is connected to the control terminal of the power switch unit through the drive circuit.

[0013] Optionally, the push-pull circuit includes: a pull-up unit and a pull-down unit;

[0014] The positive terminal of the pull-up unit is connected to the positive power supply.

[0015] The input terminal of the pull-up unit serves as the first input terminal of the push-pull circuit;

[0016] The negative terminal of the power supply of the pull-up unit is connected to the positive terminal of the power supply of the pull-down unit, and the connection point serves as the output terminal of the push-pull circuit.

[0017] The negative terminal of the power supply of the pull-down unit is connected to the negative power source;

[0018] The input terminal of the pull-down unit serves as the second input terminal of the push-pull circuit;

[0019] The middle node of the pull-up unit is connected to the middle node of the pull-down unit.

[0020] Optionally, the pull-up unit includes: a first resistor, a second resistor, and a first switching transistor;

[0021] The control terminal of the first switch is connected to one end of the first resistor and one end of the second resistor, respectively, and the connection point serves as the intermediate node of the pull-up unit.

[0022] The first terminal of the first switching transistor serves as the positive power supply terminal of the pull-up unit;

[0023] The second end of the first switching transistor is connected to the other end of the second resistor, and the connection point serves as the negative terminal of the power supply of the pull-up unit;

[0024] The other end of the first resistor serves as the input terminal of the pull-up unit.

[0025] Optionally, the first switching transistor is an NPN transistor.

[0026] Optionally, the pull-down unit includes: a third resistor, a fourth resistor, and a second switch.

[0027] The control terminal of the second switch is connected to one end of the third resistor and one end of the fourth resistor, respectively, and the connection point serves as the intermediate node of the pull-down unit.

[0028] The first end of the second switch transistor serves as the positive power supply terminal of the pull-down unit;

[0029] The second terminal of the second switch is connected to the other terminal of the fourth resistor, and the connection point serves as the negative terminal of the power supply of the pull-down unit.

[0030] The other end of the third resistor serves as the input terminal of the pull-down unit.

[0031] Optionally, the second switching transistor is a PNP transistor.

[0032] Optionally, it also includes: diodes;

[0033] The cathode of the diode is connected to the first terminal of the power switching unit;

[0034] The anode of the diode is connected to the intermediate circuit.

[0035] Optionally, capacitors may also be included;

[0036] The short-circuit desaturation detection pin of the driver chip is grounded through the capacitor.

[0037] Optionally, the driving circuit has n output terminals that correspond one-to-one with the n control terminals of the power switching unit; each output terminal of the driving circuit is connected to its corresponding control terminal in the power switching unit; n is a positive integer;

[0038] The driving circuit includes: n driving resistors;

[0039] One end of each of the driving resistors is connected, and the connection point serves as the input terminal of the driving circuit.

[0040] The other end of each of the driving resistors serves as an output terminal of the driving circuit.

[0041] Optionally, the power switching unit includes: n power switching transistors and n current sharing resistors;

[0042] Each of the power switching transistors corresponds one-to-one with each of the current sharing resistors;

[0043] One end of each of the power switching transistors serves as the first end of the power switching unit.

[0044] Each of the power switching transistors serves as a control terminal of the power switching unit.

[0045] The other end of each of the power switching transistors is connected to the second end of the power switching unit through its corresponding current sharing resistor.

[0046] As can be seen from the above technical solution, the present invention provides a drive protection circuit for a drive chip, wherein: the short-circuit desaturation detection pin of the drive chip is connected to the first terminal of the power switch unit through an intermediate circuit; the second terminal of the power switch unit is grounded; the pulse width modulation output pin of the drive chip is connected to the first input terminal of the push-pull circuit; the soft turn-off pin of the drive chip is connected to the second input terminal of the push-pull circuit; the positive and negative terminals of the power supply of the push-pull circuit are connected to the positive and negative power supplies, respectively; when the push-pull circuit receives the first control signal from the drive chip, the push-pull circuit uses the positive power supply; when the push-pull circuit receives the second control signal, the push-pull circuit uses the negative power supply; the output terminal of the push-pull circuit is connected to the control terminal of the power switch unit through the drive circuit; that is, the push-pull circuit is set between the power switch unit and the drive chip. When the power switch unit is faulty, the soft turn-off pin of the drive chip does not need to discharge the control terminal of the power switch unit, but discharges through the power switch unit, avoiding damage to the soft turn-off pin caused by excessive current at the control terminal of the power switch unit, thereby protecting the drive chip. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of a drive protection circuit for a driver chip provided in an embodiment of the present utility model;

[0049] Figure 2 This is a schematic diagram of a drive protection circuit for another driver chip provided in an embodiment of the present utility model;

[0050] Figure 3 This is a schematic diagram of a drive protection circuit for another driver chip provided in an embodiment of the present utility model;

[0051] Figure 4 This is a schematic diagram of a drive protection circuit for another driver chip provided in an embodiment of this utility model. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0053] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data used can be interchanged where appropriate so that embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0054] This application provides a drive protection circuit for a driver chip, which solves the problem that the dynamic current sharing control method for parallel power switching devices in the prior art cannot achieve circuit protection, resulting in instability of the driver chip.

[0055] See Figure 1 The drive protection circuit of the driver chip includes: push-pull circuit, drive circuit and power switching unit.

[0056] This driver chip has a short-circuit desaturation detection pin (such as...) Figure 4 The DESAT pin shown), pulse width modulation output pin (as shown) Figure 4 The PWM pins shown) and soft-shutdown pins (such as...) Figure 4 The SSW pins shown are examples, and other pins may also be included, but will not be detailed here.

[0057] The short-circuit desaturation detection pin of the driver chip is connected to the first terminal of the power switch unit through an intermediate circuit.

[0058] Specifically, the short-circuit desaturation detection pin of the driver chip is connected to the input terminal of the intermediate circuit, and the output terminal of the intermediate circuit is connected to the first terminal of the power switching unit. That is, the short-circuit desaturation detection pin of the driver chip and the first terminal of the power switching unit transmit corresponding signals, such as voltage signals, through the intermediate circuit, which can accurately monitor the operating status of the power switching unit and react quickly once abnormal conditions such as short circuit or desaturation are detected.

[0059] The intermediate circuit can be a circuit disposed between the power switching unit and the driver chip in the prior art; it does not include the drive protection circuit proposed in this application. The specific content of the intermediate circuit is not specifically limited here, but depends on the actual situation, and all are within the protection scope of this application.

[0060] The second terminal of the power switch unit is grounded.

[0061] In other words, the power switching unit, the driver chip, and the intermediate circuit form a loop, which ensures that the current in the circuit has a stable return path, thereby maintaining the normal operation of the circuit.

[0062] The pulse width modulation output pin of the driver chip is connected to the first input terminal of the push-pull circuit.

[0063] The pulse width modulation output pin of the driver chip is responsible for sending PWM signals to the push-pull circuit to control its output power.

[0064] The soft-shutdown pin of the driver chip is connected to the second input terminal of the push-pull circuit.

[0065] The soft-shutdown pin of the driver chip is used to achieve smooth circuit shutdown when needed, avoiding excessive inrush current. The driver chip also connects to a positive power supply and a negative power supply; the positive power supply voltage is VCC, and the negative power supply voltage is VEE.

[0066] The power supply terminals of the push-pull circuit are connected to the positive and negative power supplies, respectively. When the push-pull circuit receives the first control signal from the driver chip, it uses the positive power supply. When the push-pull circuit receives the second control signal, it uses the negative power supply.

[0067] Specifically, the positive terminal of the push-pull circuit is connected to a positive power source, and the negative terminal is connected to a negative power source. This allows the push-pull circuit to flexibly select the power supply based on the received control signal. Specifically, when the push-pull circuit receives the first signal from the driver chip, it selects the positive power source; when it receives the second signal, it switches to the negative power source. This design not only improves the circuit's flexibility but also enhances its stability and reliability. In other words, the output voltage of the push-pull circuit changes with the control signal from the driver chip, thereby adjusting the gate voltage of the power switching unit.

[0068] The output of the push-pull circuit is connected to the control terminal of the power switch unit through the drive circuit.

[0069] The push-pull circuit precisely controls the power switching unit to turn on and off based on the received PWM signal and soft-shutdown signal, thereby achieving effective protection and control of the entire circuit.

[0070] In summary, the driver chip's protection circuit, through the close cooperation of the push-pull circuit, the driver circuit, and the power switching unit, achieves effective protection and control of the circuit. This design not only improves the reliability and stability of the circuit but also provides strong support for its stable operation in various complex environments.

[0071] Optional, such as Figure 2 As shown, it also includes: diode D1.

[0072] The cathode of diode D1 is connected to the first terminal of the power switching unit.

[0073] The anode of diode D1 is connected to the intermediate circuit.

[0074] In the circuit, diode D1 plays a crucial connection and guiding role. Specifically, the cathode of diode D1 is connected to the first terminal of the power switching unit. This connection ensures that the power switching unit can receive the necessary signal or current through diode D1, thereby enabling normal switching operation.

[0075] The anode of diode D1 is connected to the intermediate circuit. The intermediate circuit acts as a bridge between the preceding and following circuits, further processing or converting signals from the driver chip or other control units before transmitting them to the power switching unit. Through the connection between the anode of diode D1 and the intermediate circuit, signals can be smoothly transmitted from one circuit section to another, achieving effective communication and control between circuits.

[0076] It is worth noting that diode D1 not only serves as a connector here, but also utilizes its unidirectional conductivity. This means that current can only flow through diode D1 in one direction (i.e., from cathode to anode), thus ensuring that the current and signal in the circuit can flow in the predetermined direction, avoiding unnecessary interference or damage.

[0077] In summary, diode D1, through its connection with the power switching unit and intermediate circuit, enables signal transmission and control, ensuring the normal operation of the circuit.

[0078] Optional, such as Figure 3 As shown, it also includes capacitor C1.

[0079] The short-circuit desaturation detection pin of the driver chip is grounded through capacitor C1.

[0080] Specifically, the short-circuit desaturation detection pin of the driver chip is connected to one end of capacitor C1 and one end of the intermediate circuit, respectively; the other end of capacitor C1 is grounded.

[0081] In this embodiment, the short-circuit desaturation detection pin of the driver chip is connected to the first terminal of the power switch unit through an intermediate circuit; the second terminal of the power switch unit is grounded; the pulse width modulation output pin of the driver chip is connected to the first input terminal of the push-pull circuit; the soft-shutdown pin of the driver chip is connected to the second input terminal of the push-pull circuit; the positive and negative terminals of the power supply of the push-pull circuit are connected to the positive and negative power supplies, respectively; when the push-pull circuit receives the first control signal from the driver chip, the push-pull circuit is powered by the positive power supply; when the push-pull circuit receives the second control signal, the push-pull circuit is powered by the negative power supply; the output terminal of the push-pull circuit is connected to the control terminal of the power switch unit through the driver circuit; that is, the push-pull circuit is placed between the power switch unit and the driver chip. When the power switch unit is faulty, the soft-shutdown pin of the driver chip does not need to discharge the control terminal of the power switch unit, but discharges through the power switch unit, avoiding damage to the soft-shutdown pin caused by excessive current at the control terminal of the power switch unit, thus protecting the driver chip.

[0082] Optionally, the push-pull circuit includes a pull-up unit and a pull-down unit.

[0083] The positive terminal of the pull-up unit is connected to a positive power supply to ensure sufficient voltage supply.

[0084] The input terminal of the pull-up unit serves as the first input terminal of the push-pull circuit and is connected to the pulse width modulation output pin of the driver chip to receive the drive signal from the driver chip, such as a PWM wave signal.

[0085] The negative terminal of the pull-up unit is connected to the positive terminal of the pull-down unit, and the connection point serves as the output terminal of the push-pull circuit. That is, the negative terminal of the pull-up unit is not directly grounded or left floating, but is connected to the positive terminal of the pull-down unit through a node. This connection point is also regarded as the output terminal of the push-pull circuit, used to output the processed signal.

[0086] The negative terminal of the pull-down unit is connected to a negative power source to provide the necessary voltage reference.

[0087] The input terminal of the pull-down unit serves as the second input terminal of the push-pull circuit and is connected to the soft-shutdown pin of the driver chip to receive the soft-shutdown signal from the driver chip.

[0088] The middle node of the pull-up unit is connected to the middle node of the pull-down unit.

[0089] The pull-down unit is not isolated in the circuit. Its intermediate node is connected to the intermediate node of the pull-up unit in some way. This connection may be a direct wire connection or an indirect connection through other components to achieve signal interaction and coordination between the two.

[0090] In summary, the push-pull circuit, through its carefully designed pull-up and pull-down units and their interconnections, achieves effective processing and output of the input signal.

[0091] Optional, such as Figure 4 As shown, the pull-up unit includes: a first resistor Rb, a second resistor Rx, and a first switching transistor Q1.

[0092] The control terminal of the first switch Q1 is connected to one end of the first resistor Rb and one end of the second resistor Rx, respectively. The connection point serves as the intermediate node of the pull-up unit. In other words, a connection is formed between the control terminal of the first switch Q1, one end of the first resistor Rb, and one end of the second resistor Rx. This connection point plays the role of an intermediate node in the entire pull-up unit, and it is responsible for transmitting and regulating signals in the circuit.

[0093] The first terminal of the first switching transistor Q1 serves as the positive terminal of the pull-up unit, connected to a positive power supply. That is, when the first switching transistor Q1 is turned on, the push-pull circuit is powered by a positive power supply, and the output voltage of the push-pull circuit is related to the positive power supply voltage.

[0094] The second terminal of the first switching transistor Q1 is connected to the other end of the second resistor Rx, and this connection point serves as the negative power supply terminal of the pull-up unit. In other words, the second terminal of the first switching transistor Q1 is tightly connected to the other end of the second resistor Rx. This connection point is particularly important in the entire circuit because it not only serves as the negative power supply terminal of the pull-up unit but also connects with the pull-down unit, jointly determining the output of the push-pull circuit.

[0095] The other end of the first resistor Rb serves as the input of the pull-up unit and is connected to the pulse width modulation output pin of the driver chip to receive the PWM signal from the driver chip.

[0096] Optionally, the first switching transistor Q1 is an NPN transistor.

[0097] In other words, the control terminal of the first switch Q1 is the base B of the NPN transistor, the first terminal of the first switch Q1 is the collector C of the NPN transistor, which is connected to the positive power supply, and the second terminal of the first switch Q1 is the emitter E of the NPN transistor, which is connected to the output terminal of the push-pull circuit.

[0098] In summary, the pull-up unit, through its carefully designed resistors and switching transistors, and the connections between them, effectively receives, processes, and transmits input signals, providing a solid guarantee for the overall performance of the push-pull circuit.

[0099] Optional, the pull-down unit includes: a third resistor Rs, a fourth resistor Re, and a second switch Q2.

[0100] The control terminal of the second switch Q2 is connected to one end of the third resistor Rs and one end of the fourth resistor Re, respectively. The connection point serves as the intermediate node of the pull-down unit and the intermediate node of the pull-up unit. More specifically, the control terminal of the second switch Q2 is connected to one end of the third resistor Rs, one end of the fourth resistor Re, one end of the first resistor Rb, one end of the second resistor Rx and the control terminal of the first switch Q1, respectively.

[0101] The first end of the second switch Q2 serves as the positive terminal of the power supply for the pull-down unit and is connected to the negative terminal of the power supply for the pull-up unit. More specifically, the first end of the second switch Q2 is connected to the second end of the first switch Q1 and the other end of the second resistor Rx.

[0102] The second terminal of the second switch Q2 is connected to the other terminal of the fourth resistor Re. The connection point serves as the negative terminal of the power supply for the pull-down unit. In other words, the connection point between the second terminal of the second switch Q2 and the other terminal of the fourth resistor Re is connected to the negative power supply.

[0103] The other end of the third resistor Rs serves as the input of the pull-down unit and is connected to the soft-shutdown pin of the driver chip to receive the soft-shutdown signal from the driver chip.

[0104] Optionally, the second switching transistor Q2 is a PNP transistor.

[0105] In other words, the control terminal of the second switch Q2 is the base B of the PNP transistor, the first terminal of the first switch Q1 is the emitter E of the PNP transistor, which is connected to the output terminal of the push-pull circuit, and the second terminal of the first switch Q1 is the collector C of the PNP transistor, which is connected to the negative power supply.

[0106] The first switch Q1 and the second switch Q2 mentioned above can be transistors, such as NPN or PNP transistors, or MOSFETs, or other types of transistors, which will not be elaborated here.

[0107] Optionally, the drive circuit has n output terminals that correspond one-to-one with the n control terminals of the power switch unit; each output terminal of the drive circuit is connected to its corresponding control terminal in the power switch unit.

[0108] Specifically, the first output terminal of the drive circuit is connected to the first control terminal of the power switch unit, the second output terminal of the drive circuit is connected to the second control terminal of the power switch unit, and so on, with the nth output terminal of the drive circuit connected to the nth control terminal of the power switch unit.

[0109] n is a positive integer. The specific value of n is not limited here, and all are within the scope of protection of this application.

[0110] The driving circuit includes: n driving resistors (e.g. Figure 4 R shown g1 R g2 …R gn ).

[0111] One end of each driving resistor is connected, and the connection point serves as the input terminal of the driving circuit and the output terminal of the push-pull circuit. More specifically, the connection point between each driving resistor is connected to the second terminal of the first switching transistor Q1, the first terminal of the second switching transistor Q2, and one end of the second resistor Rx, respectively.

[0112] The other end of each driving resistor serves as an output terminal of the driving circuit.

[0113] Specifically, the other end of the first driving resistor serves as the first output terminal of the driving circuit; the other end of the second driving resistor serves as the second output terminal of the driving circuit, and so on, with the other end of the nth driving resistor serving as the nth output terminal of the driving circuit.

[0114] Optionally, the power switching unit includes: n power switching transistors (e.g., ... Figure 4 The K1, K2...K shown n ) and n current-sharing resistors (such as Figure 4 R shown av1 R av2 …R avn ).

[0115] Each power switch corresponds to a current sharing resistor.

[0116] One end of each power switch transistor serves as the first end of the power switch unit.

[0117] Specifically, one end of each power switch is connected, and the connection point serves as the first end of the power switch unit. It is connected to the short-circuit desaturation detection pin of the driver chip through diode D1 and intermediate circuit.

[0118] Each power switch transistor's control terminal serves as a control terminal of the power switch unit and is connected to the corresponding output terminal of the drive circuit. More specifically, the control terminal of the first power switch transistor is connected to the other end of the first drive resistor in the drive circuit; the control terminal of the second power switch transistor is connected to the other end of the second drive resistor in the drive circuit... and so on, with the control terminal of the nth power switch transistor connected to the other end of the nth drive resistor in the drive circuit.

[0119] The other end of each power switch is connected to the second end of the power switch unit through its corresponding current sharing resistor.

[0120] Specifically, the other end of each power switch is connected to one end of its corresponding current sharing resistor, and the other end of each current sharing resistor is connected to the ground. The connection point serves as the second terminal of the power switch unit.

[0121] More specifically, the other end of the first power switch is connected to one end of the first current sharing resistor, the other end of the second power switch is connected to one end of the second current sharing resistor, and so on, with the other end of the nth power switch connected to one end of the nth current sharing resistor.

[0122] The aforementioned power switching transistors can be IGBTs, MOSFETs, SiC MOSFETs, SiC power switching transistors, GaN power switching transistors, etc. No specific limitation is made here; the choice depends on the actual situation.

[0123] Each current-sharing resistor can mitigate the dynamic current imbalance caused by the asymmetry of stray inductance in the power circuit.

[0124] In this embodiment, soft-shutdown protection is implemented for short-circuit faults that may occur in parallel applications of any number of power switches. This protection function relies on a transistor push-pull circuit as the driving protection mechanism, ensuring rapid soft-shutdown upon detection of a short-circuit fault, while guaranteeing no adverse impact on the gate voltage under normal operating conditions. The driving protection circuit proposed in this application can be flexibly applied to power switch systems with any configuration.

[0125] The following is based on Figure 4The structure shown illustrates the operation of the driver protection circuit of the driver chip:

[0126] During normal operation, the driver chip operates as follows: the pulse width modulation (PWM) output pin sends a PWM drive signal, the desaturation detection pin monitors whether the power switch's on-state current exceeds the set current threshold, and the soft-shutdown pin is at high impedance during normal operation. When the device's on-state current exceeds the set current threshold, the soft-shutdown pin goes low, the PWM output pin goes high impedance, and the power switch transitions from the on state to the off state.

[0127] (1) The logic of the driver chip during normal operation is as follows:

[0128] The pulse width modulation (PWM) output pin outputs a PWM drive signal, and its desaturation detection pin monitors whether the on-state current of the power switch exceeds a preset current threshold. The soft-shutdown pin presents high impedance under normal operating conditions. Once the on-state current exceeds the set threshold, the soft-shutdown pin switches to a low level, and the PWM output pin enters a high-impedance state, causing the power switch to switch from on to off.

[0129] When the PWM output of the driver chip is high, through Rb (such as...) Figure 4 Current path ②) charges node 1, and then node 1 activates the upper NPN transistor in the push-pull circuit via current path ⑤. After the NPN transistor is turned on, the VCC power supply charges node 2 along current paths ⑥ and ⑦. Due to the on-state voltage drop ΔVce between the collector and emitter of the NPN transistor, when the transistor is fully turned on, the voltage of node 2 is VCC minus ΔVce (V2 = VCC - ΔVce). At this time, the voltage of node 1 is VCC. Through Rx and current path ④, the voltage of node 2 rises from V2 to VCC, ensuring that there is no voltage loss after the PWM high level passes through the push-pull circuit. Node 2 then charges node 2 through Rx. g1 R g2 …R gn Equal driving resistors are used to synchronously turn on power switching transistors K1, K2...Kn. "Node 1" is the intermediate node mentioned above, and "Node 2" is the output terminal of the push-pull circuit.

[0130] Conversely, when the PWM output is low, "Node 1" is discharged through Rb and current path ①. Then, "Node 1" activates the lower PNP transistor in the push-pull circuit through current path ⑩. After the PNP transistor is turned on, "Node 2" discharges along current paths ⑧ and ⑨. Similarly, due to the on-state voltage drop ΔVce between the collector and emitter of the PNP transistor, when the transistor is fully turned on, the voltage of "Node 2" is VEE plus ΔVce (i.e., V2 = VEE + ΔVce). At this time, the voltage of "Node 1" is VEE. Through Rx and current path ③, the voltage of "Node 2" drops from V2 to VEE, ensuring that there is no voltage loss after the PWM low level passes through the push-pull circuit. Simultaneously, "Node 2" turns off the power switching transistors K1, K2…K through the same group of drive resistors. n .

[0131] (2) When an overcurrent or short-circuit fault occurs in the power switching unit, the logic of the driver chip is as follows:

[0132] If the power switching transistors K1, K2...K n In the event of an overcurrent or short-circuit fault, the DESAT function of the driver chip will be activated, causing the soft-shutdown pin to go low and the pulse width modulation output pin to enter a high-impedance state. At this time, "Node 1" discharges through Rs and Re (the discharge current path is IRs and IRe), and activates the PNP transistor of the lower transistor through current path ⑩, which in turn causes "Node 2" to discharge through current paths ⑧ and ⑨, thereby synchronously turning off all power switching transistors.

[0133] This solution implements soft-shutdown protection through a push-pull circuit, avoiding the process of directly discharging the power switch gate through multiple resistors in conventional solutions. This reduces the commutation problems that may occur when the power switch gate is directly connected to the soft-shutdown pin of the driver chip through a resistor.

[0134] The drive protection circuit in this embodiment has a gate voltage regulation function, which can achieve soft-shutdown protection for the power switch without interfering with the gate voltage waveform. This ensures the lossless transmission of the gate voltage of the power switch during normal operation and provides soft-shutdown protection under short-circuit conditions. Furthermore, under short-circuit conditions, the soft-shutdown pin of the driver chip does not directly discharge the gate current; instead, the lower PNP transistor handles it. Therefore, the discharge current handled by the soft-shutdown pin is limited (typically only a few amperes), thus eliminating the limitation on the number of power switches connected in parallel. During design, it is only necessary to ensure that the collector current of the lower PNP transistor is greater than the gate charge current to be discharged, thereby avoiding the limitation on the number of power switches connected in parallel.

[0135] The features described in the various embodiments of this specification can be substituted for or combined with each other. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0136] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this invention.

[0137] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A drive protection circuit for a driver chip, characterized in that, include: Push-pull circuit, drive circuit, and power switching unit; The short-circuit desaturation detection pin of the driver chip is connected to the first terminal of the power switch unit through an intermediate circuit; The second terminal of the power switch unit is grounded; The pulse width modulation output pin of the driver chip is connected to the first input terminal of the push-pull circuit; The soft-shutdown pin of the driver chip is connected to the second input terminal of the push-pull circuit; The positive and negative terminals of the push-pull circuit are connected to a positive power supply and a negative power supply, respectively. When the push-pull circuit receives a first control signal from the driver chip, the push-pull circuit is powered by the positive power supply. When the push-pull circuit receives a second control signal, the push-pull circuit is powered by the negative power supply. The output terminal of the push-pull circuit is connected to the control terminal of the power switch unit through the drive circuit.

2. The drive protection circuit for the driver chip according to claim 1, characterized in that, The push-pull circuit includes: a pull-up unit and a pull-down unit; The positive terminal of the pull-up unit is connected to the positive power supply. The input terminal of the pull-up unit serves as the first input terminal of the push-pull circuit; The negative terminal of the power supply of the pull-up unit is connected to the positive terminal of the power supply of the pull-down unit, and the connection point serves as the output terminal of the push-pull circuit. The negative terminal of the power supply of the pull-down unit is connected to the negative power source; The input terminal of the pull-down unit serves as the second input terminal of the push-pull circuit; The middle node of the pull-up unit is connected to the middle node of the pull-down unit.

3. The drive protection circuit for the driver chip according to claim 2, characterized in that, The pull-up unit includes: a first resistor, a second resistor, and a first switching transistor; The control terminal of the first switch is connected to one end of the first resistor and one end of the second resistor, respectively, and the connection point serves as the intermediate node of the pull-up unit; The first terminal of the first switching transistor serves as the positive power supply terminal of the pull-up unit; The second end of the first switching transistor is connected to the other end of the second resistor, and the connection point serves as the negative terminal of the power supply of the pull-up unit; The other end of the first resistor serves as the input terminal of the pull-up unit.

4. The drive protection circuit for the driver chip according to claim 3, characterized in that, The first switching transistor is an NPN transistor.

5. The drive protection circuit for the driver chip according to claim 2, characterized in that, The pull-down unit includes: a third resistor, a fourth resistor, and a second switch. The control terminal of the second switch is connected to one end of the third resistor and one end of the fourth resistor, respectively, and the connection point serves as the intermediate node of the pull-down unit; The first end of the second switch transistor serves as the positive power supply terminal of the pull-down unit; The second terminal of the second switch is connected to the other terminal of the fourth resistor, and the connection point serves as the negative terminal of the power supply of the pull-down unit. The other end of the third resistor serves as the input terminal of the pull-down unit.

6. The drive protection circuit for the driver chip according to claim 5, characterized in that, The second switching transistor is a PNP transistor.

7. The drive protection circuit for the driver chip according to claim 1, characterized in that, Also includes: diode; The cathode of the diode is connected to the first terminal of the power switching unit; The anode of the diode is connected to the intermediate circuit.

8. The drive protection circuit for the driver chip according to claim 1, characterized in that, Also includes: capacitance; The short-circuit desaturation detection pin of the driver chip is grounded through the capacitor.

9. The drive protection circuit for the driver chip according to claim 1, characterized in that, The driving circuit has n output terminals that correspond one-to-one with the n control terminals of the power switching unit; Each output terminal of the drive circuit is connected to its corresponding control terminal in the power switch unit. n is a positive integer; The driving circuit includes: n driving resistors; One end of each of the driving resistors is connected, and the connection point serves as the input terminal of the driving circuit. The other end of each of the driving resistors serves as an output terminal of the driving circuit.

10. The drive protection circuit for the driver chip according to claim 1, characterized in that, The power switching unit includes: n power switching transistors and n current sharing resistors; Each of the power switching transistors corresponds one-to-one with each of the current sharing resistors; One end of each of the power switching transistors serves as the first end of the power switching unit. Each of the power switching transistors serves as a control terminal of the power switching unit. The other end of each of the power switching transistors is connected to the second end of the power switching unit through its corresponding current sharing resistor.

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