A wiring harness overheat protection circuit and drive circuit

Abstract

The utility model discloses a kind of wire harness overheat protection circuit and drive circuit, it is related to circuit protection technical field, to solve the problem that traditional wire harness protection scheme cannot self-recovery or cost is high after failure, provide a kind of wire harness overheat protection circuit, through self-recovery fuse realizes repeatable I2T protection function, can effectively protect the wire harness of high-side driver chip rear stage.In addition, the current size is reduced by conversion module in the circuit, so that the current specification requirement of self-recovery fuse is lower, self-recovery fuse with smaller size and lower cost can be selected, thereby the cost is greatly reduced.On the other hand, the circuit also realizes the enable control of high-side driver chip by protection detection module.Thus, without self-recovery fuse being arranged at the output end of high-side driver chip, the protection of rear-stage wire harness can also be realized, which provides a prerequisite condition for the scheme of reducing the current specification requirement of self-recovery fuse based on conversion module.

Description

Technical Field

[0001] This utility model relates to the field of circuit protection technology, and in particular to a wire harness overheat protection circuit and a drive circuit. Background Technology

[0002] Common high-side driver chips only have overcurrent shutdown functionality and offer no protection for wiring harnesses. When the driver chip's driving capability exceeds the wiring harness's overload capacity, or under certain operating conditions the wiring harness may fail before the driver chip, this can lead to wiring harness burn-out. Since wiring harnesses in vehicles are centrally routed, once burn-out occurs, it often damages related wiring harnesses, resulting in very high repair costs.

[0003] Currently, there are two main types of common overload protection solutions for wire harnesses. One is a fuse. While fuses can quickly melt and protect the wire harness during high-current overloads such as short circuits, once a fuse blows, it cannot be reset and requires manual replacement, resulting in poor flexibility and disruption to normal operation. The other type is an electronic fuse driver chip, which integrates I2T (current squared time product) wire harness protection within the high-side driver chip. However, this type of chip is often much more expensive than ordinary high-side chips, making its widespread application difficult in practice.

[0004] Therefore, those skilled in the art urgently need a wire harness overheat protection circuit to achieve I2T protection for the wire harness, while also taking into account the advantages of recoverability and low cost after a fault. Utility Model Content

[0005] The purpose of this invention is to provide a wire harness overheat protection circuit and a drive circuit to achieve I2T protection for the wire harness, while also taking into account the advantages of recoverability and low cost after a fault.

[0006] To solve the above-mentioned technical problems, this utility model provides a wire harness overheat protection circuit, including: a self-resetting fuse, a conversion module, and a detection and protection module;

[0007] The input terminal of the conversion module is connected to the output terminal of the high-side driver chip, and the output terminal of the conversion module is connected to the self-resetting fuse, for converting the first current signal output by the high-side driver chip into a second current signal output; wherein, the current value of the second current signal is less than that of the first current signal;

[0008] The detection and protection module is connected to the resettable fuse and the enable terminal of the high-side driver chip, and is used to detect the state of the resettable fuse and invalidate the enable signal connected to the enable terminal of the high-side driver chip when the resettable fuse is in a protected state.

[0009] In one optional embodiment, the conversion module includes: a sampling resistor, an amplifier circuit, and a conversion resistor;

[0010] The acquisition resistor is connected in series at the output terminal of the high-side driver chip. The input terminal of the amplifier circuit is connected to both ends of the acquisition resistor. The output terminal of the amplifier circuit is connected to the first end of the resettable fuse. The second end of the resettable fuse is connected to the first end of the conversion resistor. The second end of the conversion resistor is grounded.

[0011] In one optional embodiment, the conversion module further includes a voltage follower circuit;

[0012] The input terminal of the voltage follower circuit is connected to the output terminal of the amplifier circuit, and the output terminal of the voltage follower circuit is connected to the first terminal of the self-resetting fuse.

[0013] In one optional embodiment, the conversion module further includes: a power switching transistor;

[0014] The controlled terminal of the power switch is connected to the output terminal of the voltage follower circuit, the first terminal of the power switch is connected to the power supply, and the second segment of the power switch is connected to the first terminal of the resettable fuse.

[0015] In one optional embodiment, the enable signal is a high-level signal;

[0016] The detection and protection module includes: a switch module;

[0017] The controlled terminal of the switching module is connected to the first terminal of the switching resistor, the first terminal of the switching module is connected to the enable terminal of the high-side driver chip, and the second terminal of the switching module is grounded.

[0018] The switch module is turned off when a first detection signal is received, and turned on when a second detection signal is received; wherein, the first detection signal is the signal at the second end of the self-resetting fuse when the self-resetting fuse is in a normal state, and the second detection signal is the signal at the second end of the self-resetting fuse when the self-resetting fuse is in a protected state.

[0019] In one alternative embodiment, the enable signal is output by an enable control module;

[0020] The first end of the switch module is also connected to the detection end of the enable control module; the enable control module stops outputting the enable signal when a low-level signal is received at the detection end.

[0021] In one optional embodiment, the switching module includes: a first switching transistor and a second switching transistor;

[0022] The controlled terminal of the first switching transistor is connected to the first terminal of the switching resistor, the second terminal of the first switching transistor is connected to the second terminal of the switching resistor, and the first terminal of the first switching transistor is connected to the controlled terminal of the second switching transistor.

[0023] The first terminal of the second switch is connected to the enable terminal of the high-side driver chip, and the second terminal of the second switch is grounded.

[0024] In one optional embodiment, the switch module further includes: a pull-up circuit;

[0025] The pull-up circuit is connected to the first terminal of the first switching transistor.

[0026] In one optional embodiment, the wire harness overheat protection circuit is a removable surface mount circuit, mounted at the output of the high-side driver chip that requires wire harness protection.

[0027] To solve the above-mentioned technical problems, this utility model also provides a driving circuit, including the wire harness overheat protection circuit as described above, and a high-side driving chip.

[0028] This utility model provides a wire harness overheat protection circuit, including a resettable fuse, a conversion module, and a detection and protection module. The resettable fuse enables I2T functionality, thus protecting the wire harness. As a resettable protection device, it can recover from a protected state (high resistance state) to a normal state (low resistance state) after a fault is cleared, ready for the next protection attempt. This eliminates the need for frequent replacements, making implementation more flexible and convenient, and avoiding the device and maintenance costs associated with frequent fuse replacements. Furthermore, this circuit reduces the output current of the high-side driver chip through the conversion module, resulting in a lower actual current connected to the resettable fuse compared to the actual output current of the high-side driver chip. In other words, the conversion module can match the current characteristics of the low-power resettable fuse to the current of the high-power load wire harness connected to the output of the high-side driver chip. Therefore, compared to directly connecting the resettable fuse to the high-power load wire harness, this circuit can use a lower-power (corresponding to a lower current specification) resettable fuse, resulting in lower costs. It is also cheaper and easier to implement than electronic fuse chips that integrate I2T functionality.

[0029] On the other hand, although the conversion module can reduce the power requirement of the resettable fuse, the resettable fuse is not connected in series in the output path of the high-side driver chip and cannot protect the wire harness through its own switching. Therefore, this circuit also solves this problem through a detection protection module. When the detection protection module detects that the resettable fuse has entered the protection state, it disables the enable signal of the high-side driver chip, causing it to stop outputting, thereby achieving the protection of the wire harness.

[0030] The driving circuit provided by this utility model corresponds to the above-mentioned wire harness overheat protection circuit and has the same effect. Attached Figure Description

[0031] To more clearly illustrate the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a wire harness protection scenario;

[0033] Figure 2 This is a schematic diagram of a wiring harness protection method using an electronic fuse chip.

[0034] Figure 3 A structural diagram of a wire harness overheat protection circuit provided in an embodiment of this utility model;

[0035] Figure 4 A structural diagram of a conversion module provided in an embodiment of this utility model;

[0036] Figure 5 A circuit diagram of a wire harness overheat protection circuit provided for an embodiment of this utility model;

[0037] Among them, 11 is a self-resetting fuse, 12 is a conversion module, 13 is a detection and protection module, 21 is a high-side driver chip, and 22 is an enable control module. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0039] The core of this utility model is to provide a wire harness overheat protection circuit and a drive circuit.

[0040] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] like Figure 1As shown, traditional high-side driver chips only integrate overcurrent and overtemperature protection functions, meaning they shut down the output when the current reaches a threshold or the chip temperature reaches a threshold. They cannot adopt different protection time periods based on different current values, lacking flexibility and comprehensiveness in protection. Therefore, to achieve wire harness protection, the following two common solutions are available:

[0042] 1. Fuse;

[0043] The special material of fuses requires different fusing times depending on the overload current; the larger the overload current, the shorter the fusing time. In this way, the wiring harness and fuse can withstand relatively small current overloads, such as a stalled motor, and also protect the wiring harness by quickly blowing the fuse during large current overloads, such as a short circuit. However, once a fuse blows, it cannot be reset and must be manually replaced to continue use, resulting in poor flexibility and disruption to normal operation.

[0044] 2. Electronic fuse driver chip;

[0045] like Figure 2 As shown, the electronic fuse driver chip is a chip that integrates I2T (current squared product of time) function within the high-side driver chip, which can realize wire harness protection. However, the cost of this type of chip is often much higher than that of ordinary high-side chips, making it difficult to widely use in practical applications.

[0046] To address the aforementioned problems, this application provides a wiring harness overheat protection circuit, such as... Figure 3 As shown, the system includes: a resettable fuse 11, a conversion module 12, and a detection and protection module 13. The input terminal of the conversion module 12 is connected to the output terminal of the high-side driver chip 21, and the output terminal of the conversion module 12 is connected to the resettable fuse 11. It is used to convert the first current signal output by the high-side driver chip 21 into a second current signal output; wherein the current value of the second current signal is less than that of the first current signal. The detection and protection module 13 is connected to the resettable fuse 11 and the enable terminal of the high-side driver chip 21. It is used to detect the state of the resettable fuse 11 and, when the resettable fuse 11 is in a protected state, invalidate the enable signal connected to the enable terminal of the high-side driver chip 21.

[0047] The resettable fuse 11 is an overcurrent electronic protection component. Utilizing its temperature-sensitive material properties, it maintains low resistance during normal operation and rapidly switches to a high-resistance state to cut off the current when the circuit experiences overcurrent or excessive temperature. After the fault is cleared, it automatically returns to its initial state, achieving a repetitive protection function. This component is classified into two types based on material: polymeric positive temperature coefficient thermistors (PPTC) and ceramic positive temperature coefficient thermistors (CPTC). This embodiment does not limit the specific type of resettable fuse 11; all are based on PTC elements. However, the PPTC type has advantages such as low resistance, fast response, and impact resistance, making it a preferred option.

[0048] The function of the conversion module 12 is to reduce the output current of the high-side driver chip 21 (i.e., the current flowing through the wiring harness) and provide it to the resettable fuse 11 for current protection. In related technologies, there are various solutions that can achieve current reduction, such as current conversion circuits, current transformers, and even series resistors. Furthermore, besides direct current conversion, current conversion can also be achieved indirectly through voltage conversion; this embodiment does not limit these methods.

[0049] However, one of the requirements for using the conversion module 12 in this embodiment is that it should not affect the normal output of the high-side driver chip 21. That is, when the conversion module 12 performs current conversion, it should not affect the electrical parameters of the output terminal of the high-side driver chip 21. In other words, directly connecting a resistor in series at the output terminal of the high-side driver chip 21 is not applicable.

[0050] It should be noted that, based on the settings of the conversion module 12, the current required for the self-resetting fuse 11 to detect can be reduced. For example, assume the output current of the high-side driver chip 21 is 10A (i.e., the current value I of the first current signal). L=10A); the scaling factor of the conversion module 12 is 100 times; then the current value IS of the second detection current signal input to the self-resetting fuse 11 is 0.1A; that is, originally a self-resetting fuse 11 with a specification corresponding to 10A was required at the output of the high-side driver chip 21, but based on the setting of the conversion module 12, only a model with a specification corresponding to 0.1A is required. It is not difficult to see that for devices such as fuses, the smaller the corresponding current specification, the lower its size and cost. Therefore, the setting of the conversion module 12 can effectively reduce the cost and size of the self-resetting fuse 11. For I2T (current squared and time product) protection of high-power wire harnesses (i.e., the current in the wire harness is greater than a certain value), this cost reduction is even higher than the cost required to set the conversion module 12. Therefore, in the I2T protection scenario of high-power wire harnesses, the addition of the conversion module 12 is beneficial to reducing the cost of the entire circuit.

[0051] On the other hand, as mentioned above, although the conversion module 12 can significantly reduce the size and cost of the resettable fuse 11, it cannot be connected in series in the wiring harness because it cannot affect the normal output of the high-side driver chip 21. Similarly, the resettable fuse 11 cannot be connected in series in the wiring harness, meaning it cannot directly cut off the output of the high-side driver chip 21 through its high-impedance state when triggering protection, thus failing to protect the wiring harness.

[0052] To address this issue, this circuit incorporates a detection and protection module 13. The detection and protection module 13 detects whether the resettable fuse 11 has entered a protection state to control whether the enable signal of the high-side driver chip 21 is disabled. When the enable signal of the high-side driver chip 21 is disabled, the high-side driver chip 21 has no output, thus protecting the wiring harness downstream of the high-side driver chip 21 from burn-out. The resettable fuse 11 has two states: a normal state and a protection state. The normal state is also called the low-resistance state, and the protection state is also called the high-resistance state. Therefore, the "detection" part of the detection and protection module 13 detects the resistance value of the resettable fuse 11. Since various mature resistance detection schemes already exist, this embodiment does not limit the specific structure of the detection part of the detection and protection module 13; a suitable implementation scheme can be freely selected according to actual needs. The "protection" part of the detection and protection module 13 handles the disablement of the enable signal. This part should be adapted to the specific form of the enable signal. For example, the enable signals of common chips are mostly high-level or low-level signals. High-side driver chips 21 commonly use a high-level signal as the enable signal EN. When the enable signal is high, this can be achieved by cutting off the path between the enable signal and the enable terminal of the high-side driver chip 21, or by pulling the enable terminal of the high-side driver chip 21 low. Both of these functions can be implemented using a simple switching module. For example, the switching module can control the on / off state of the circuit containing the enable terminal of the high-side driver chip 21, or it can control whether the enable terminal of the high-side driver chip 21 is grounded using a switching module and a pull-down circuit. Similarly, when the enable signal is low, it can be invalidated by pulling up the enable terminal of the high-side driver chip 21.

[0053] As described above, the wire harness overheat protection circuit provided in this application achieves repeatable I2T protection through the self-resetting fuse 11, effectively protecting the wire harness downstream of the high-side driver chip 21. Furthermore, the circuit reduces the current through the conversion module 12, lowering the current specification requirement for the self-resetting fuse 11. This allows for the selection of a smaller, lower-cost self-resetting fuse 11, significantly reducing costs. On the other hand, the circuit also enables the high-side driver chip 21 through a protection detection module, eliminating the need for the self-resetting fuse 11 to be located at the output of the high-side driver chip 21 while still protecting the downstream wire harness. This provides a prerequisite for a solution based on the conversion module 12 to reduce the current specification requirement of the self-resetting fuse 11.

[0054] On the other hand, this embodiment provides an optional implementation of the conversion module 12. For example... Figure 4 As shown, the conversion module 12 includes: a data acquisition resistor (R... S1 ), amplifier circuit (U1, R1~R4) and switching resistor (RS2 The acquisition resistor is connected in series at the output terminal of the high-side driver chip 21. The input terminal of the amplifier circuit is connected to both ends of the acquisition resistor. The output terminal of the amplifier circuit is connected to the first end of the resettable fuse 11. The second end of the resettable fuse 11 is connected to the first end of the conversion resistor. The second end of the conversion resistor is grounded.

[0055] It should be noted that, Figure 4 The amplifier circuit shown is only one possible implementation. Figure 4 In this circuit, voltage amplification is achieved through a non-inverting operational amplifier circuit. One possible implementation is to set R1=R2 and R3=R4. In this case, R3 / R1 represents the amplification factor of the non-inverting operational amplifier circuit, making it easier to implement.

[0056] Furthermore, such as Figure 4 As shown, this embodiment also provides a further implementation scheme, wherein the conversion module 12 further includes a voltage follower circuit (U2, R5). The input terminal of the voltage follower circuit is connected to the output terminal of the amplifier circuit, and the output terminal of the voltage follower circuit is connected to the first terminal of the resettable fuse 11 (PTC).

[0057] The voltage follower circuit is used to follow the voltage, so that the voltage on the left side of R5 is equal to the voltage on the left side of R7. This ensures that the voltage across the switching resistor is the output voltage of the amplifier circuit, stabilizing the voltage and facilitating subsequent calculations.

[0058] As can be seen from the above, this embodiment indirectly achieves current reduction through an amplifier circuit, and its specific principle is as follows:

[0059] The resistance R is collected S1 Used to convert the load current signal I at the output terminal of the high-side driver chip 21 L (That is, the first current signal mentioned above) is converted into a voltage signal. Assuming that the amplification factor of the non-inverting operational amplifier circuit is 20 times based on the setting of R3 / R1, then:

[0060] ;

[0061] Among them, U S R is the output voltage value of the non-inverting operational amplifier circuit; S1 To acquire the resistance value of the resistor; I L This is the current value of the load current signal.

[0062] The function of the voltage follower circuit is to make the voltage U on the left side of R5... S equal to the voltage on the left side of R7 Then we have:

[0063] ;

[0064] Among them, I S R is the current value flowing through the switching resistor; S2 This is the resistance value of the conversion resistor.

[0065] Therefore, when I L When it is 10A, I S The rated current is 0.1A. Therefore, when the load requires a 10A fuse to protect the wiring harness, this solution only requires a 0.1A resettable fuse 11 to achieve the same protection. This significantly reduces costs, and the resettable fuse 11 is reusable. Compared to traditional fuses, it offers higher reliability, and compared to currently available electronic fuse chips, it is relatively inexpensive and flexible in application.

[0066] Additionally, it should be noted that the voltage follower circuit is not necessary in the aforementioned current reduction principle. When the voltage follower circuit is absent, the output of amplifier circuit U1 is directly connected to the switching resistor R. S2 The first end can be connected, that is: I S =U S ÷R S2 =0.01I L Therefore, the implementation scheme provided in this embodiment only requires an amplifier circuit and a switching resistor to achieve current reduction. Its circuit structure is simple, reliable, and easy to implement.

[0067] Furthermore, since the output driving capability of the voltage follower circuit U2 is limited in practical applications, it may not meet the needs of the subsequent self-resetting fuse 11 and the subsequent detection and protection module 13. Therefore, this embodiment provides a further implementation scheme based on the above embodiment. Figure 4 As shown, the conversion module 12 also includes a power switch (Q1). The controlled terminal of the power switch is connected to the output terminal of the voltage follower circuit, the first terminal of the power switch is connected to the power supply, and the second terminal of the power switch is connected to the first terminal of the resettable fuse 11.

[0068] In this embodiment, the power switch Q1 amplifies the current output by the voltage follower circuit U2 to meet the driving requirements of the subsequent circuit.

[0069] It should be noted that the above embodiments are only several optional implementations of the conversion module 12, and are not limited to only these few implementations. For example, some current-limiting resistors can also be set in the conversion module 12, such as... Figure 4 R5~R7 in the circuit are used to handle current surges and improve circuit stability.

[0070] On the other hand, apart from the conversion module 12, this application also provides an optional implementation scheme for the specific implementation of the detection protection module 13. As described in the above embodiments, the enable signal of the high-side driver chip 21 is mostly a high-level signal. For this scenario, the detection protection module 13 provided in this embodiment includes: a switch module. The controlled terminal of the switch module is connected to the first terminal of the conversion resistor, the first terminal of the switch module is connected to the enable terminal of the high-side driver chip 21, and the second terminal of the switch module is grounded; the switch module is turned off when the first detection signal is received, and the switch module is turned on when the second detection signal is received; wherein, the first detection signal is the signal at the second terminal of the self-resetting fuse 11 when the self-resetting fuse 11 is in the normal state, and the second detection signal is the signal at the second terminal of the self-resetting fuse 11 when the self-resetting fuse 11 is in the protection state.

[0071] In other words, as described in the above embodiments, this embodiment provides a scheme for wire harness protection by controlling whether the enable terminal of the high-side driver chip 21 is grounded through a switching module. Specifically, when the self-resetting fuse 11 triggers protection, the switching module responds to the second detection signal by conducting and pulling the enable terminal of the high-side driver chip 21 low to invalidate the enable signal; at this time, the high-side driver chip 21 is not enabled and therefore has no output, and the wire harness downstream of the high-side driver chip 21 is protected; when the fault is cleared and the self-resetting fuse 11 returns to normal, the switching module responds to the first detection signal by turning off; at this time, it does not have any additional impact on the enable terminal of the high-side driver chip 21, and the high-side driver chip 21 can be enabled normally and thus output normally.

[0072] Regarding the first and second detection signals mentioned above, based on the switching module and switching resistor R provided in this embodiment... S2 The connection relationship between them. When the resettable fuse 11 is in the normal state, i.e., the low-resistance state, the output of the voltage follower circuit U2 can reach the switching resistor R through the resettable fuse 11. S2 The first terminal. And since the resettable fuse 11 is in a low-resistance state, the switching resistor R S2 The voltage across the terminals can be approximated as the output of the voltage follower circuit U2. That is, the first detection signal can be approximated as a high-level signal. When the resettable fuse 11 is in the protected state (i.e., the high-impedance state), the output of the voltage follower circuit U2 and the switching resistor R... S2 The path between the first terminals is effectively broken, and the switching resistor R S2 The first end is essentially suspended. That is, the second detection signal can be approximated as a low-level signal or a high-impedance signal. Responding to high or low levels to achieve self-on / off switching is a common function of various electronic switches; therefore, the switch module in this embodiment can be an electronic switch such as a switching transistor.

[0073] As can be seen from the above, the detection and protection module 13 provided in this embodiment can achieve the functions required by the above embodiment with only one switch module. Its circuit structure is simple and reliable, and its response speed is fast. It can cut off the output of the high-side driver chip 21 in time when needed, providing more effective protection for the wire harness.

[0074] Furthermore, while the above embodiments have illustrated that the switching module can be implemented using an electronic switch, this embodiment also provides a further implementation scheme. For example... Figure 5 As shown, the aforementioned switching module specifically includes a first switching transistor (Q2) and a second switching transistor (Q3). The controlled terminal of the first switching transistor is connected to the first terminal of the switching resistor, the second terminal of the first switching transistor is connected to the second terminal of the switching resistor, and the first terminal of the first switching transistor is connected to the controlled terminal of the second switching transistor. The first terminal of the second switching transistor is connected to the enable terminal of the high-side driver chip 21, and the second terminal of the second switching transistor is grounded.

[0075] This embodiment provides a two-stage switching module consisting of two cascaded switching transistors. It should be noted that, in addition to the first switching transistor Q2 and the second switching transistor Q3, the switching module may also include other devices that cooperate with the switching transistors, such as... Figure 5 The voltage divider resistors R8 and R9 are used in conjunction with the voltage divider resistors R11 and R12 of the second switch Q3. R8 can also serve as the base current-limiting resistor for the first switch Q2, and R9 serves as the bias resistor between the emitter and base of the first switch Q2. Similarly, R11 also serves as the base current-limiting resistor for the second switch Q3, and R12 serves as the bias resistor between the emitter and base of the second switch Q3.

[0076] Furthermore, in conjunction with the specific structure described above, the specific principle by which this embodiment can achieve the above-mentioned switch module function will be explained:

[0077] 1. When the resettable fuse 11 is in the normal state:

[0078] At this time, the internal resistance of the resettable fuse 11 is very small. After voltage division by R8 and R9, the voltage at Q2 is U be The voltage (i.e., the base-emitter voltage drop of Q2) is very small, so Q2 is off. Since Q2 is off, Q3 is also off, and the enable terminal of the high-side driver chip 21 will not be pulled down to ground by Q3, which means it is normally enabled.

[0079] 2. When the resettable fuse 11 is in the protected state:

[0080] At this point, the internal resistance of the resettable fuse 11 is close to infinity. A significant voltage difference will be generated across the resettable fuse 11 upon triggering the protection, which will open Q2. Once Q2 is open, Q3 will also open accordingly. The enable pin of the high-side driver chip 21 is pulled down to ground by Q3, thus rendering the enable ineffective.

[0081] Therefore, this embodiment provides an optional specific structure for the switching module. It utilizes a two-stage switching structure composed of two switching transistors, resulting in a simple and reliable circuit structure, fast response speed, and good timely protection of the wiring harness.

[0082] Furthermore, based on the solutions described in the above embodiments, this embodiment also provides a further implementation scheme. For example... Figure 5 As shown, the switching module also includes a pull-up circuit (R10 and pull-up power supply VCC). The pull-up circuit is connected to the first terminal of the first switching transistor.

[0083] It should be noted that the pull-up circuit in this embodiment serves the following purpose: after the resettable fuse 11 triggers protection, its resistance will not decrease for a short period of time. In conjunction with the pull-up circuit provided in this embodiment, the first switching transistor Q2 can remain in the on state for a period of time (until the resettable fuse 11 returns to its normal state). That is, after protection triggering, the enable function remains inactive for a period of time. This avoids short-term high-frequency enabling and disabling of the high-side driver chip 21 due to fluctuations or high-frequency protection triggering. This helps improve the service life of the high-side driver chip 21 and better ensures the protection effect on the wiring harness.

[0084] On the other hand, as can be seen from the above embodiments, a key aspect of achieving harness protection in this embodiment is invalidating the enable signal of the high-side driver chip 21 when necessary. However, it should be noted that this enable signal is not generated by this circuit. In practical applications, the high-side driver chip 21 is used to drive different systems or functional units. Based on the control needs of these systems or functional units, the high-side driver chip 21 will be enabled accordingly. That is, the enable signal of the high-side driver chip 21 is generated by the control device originally used to control the enabling of the high-side driver chip 21 in its application, and is unrelated to this circuit. This circuit is only used to invalidate this enable signal when PTC protection is triggered.

[0085] That is, this application also provides an optional embodiment, such as... Figure 5 As shown: The enable signal (EN) is output by the enable control module 22 (MCU). The first terminal of the switch module is also connected to the detection terminal (DET) of the enable control module 22; the enable control module 22 stops outputting the enable signal when a low-level signal is received at the detection terminal.

[0086] This embodiment does not limit the specific type of controller. The choice should be determined based on the actual application of the high-side driver chip 21. For example... Figure 5 As shown, the high-side driver chip 21 is enabled by a microcontroller unit (MCU), and the enable control module 22 mentioned above is this MCU.

[0087] This MCU itself can enable control of the high-side driver chip 21. Furthermore, this circuit can also provide I2T protection for the high-side driver chip 21. Therefore, when the two are combined, the enable control module 22 can stop outputting the enable signal when a low-level signal is applied to the detection terminal. This achieves redundancy by disabling the enable signal. It also ensures that even if the self-resetting fuse 11 recovers from its fault, the output of the high-side driver chip 21 will not automatically recover, further improving the reliability of the I2T protection.

[0088] Furthermore, after the introduction of the enable control module 22, such as Figure 5 As shown, the principle of the detection terminal receiving a low-level signal is the same as the principle of pulling down the enable signal to invalidate the enable. That is, the protection trigger of the self-resetting fuse 11 causes the switching module to pull down the voltage at the enable terminal and the detection terminal of the enable control module 22, which is equivalent to connecting a low-level signal to the detection terminal of the enable control module 22.

[0089] Furthermore, such as Figure 5 As shown, current-limiting resistors (R14, R15) can also be set at the enable and detection terminals of the enable control module 22 to protect the ports of the enable control module 22. In addition, a pull-down circuit (R13) can be connected at the enable terminal of the high-side driver chip 21 to ensure that the output of the high-side driver chip 21 is turned off when the enable terminal of the enable control module 22 does not output a high-level signal.

[0090] On the other hand, it is not difficult to see from the above embodiments that the wire harness overheat protection circuit provided in this application is independent of the high-side driver chip 21. It only needs to be connected to the output terminal of the high-side driver chip 21 that needs I2T protection to achieve the protection of the high-side driver chip 21.

[0091] Based on this, this embodiment also provides a further implementation scheme: the wire harness overheat protection circuit is a removable surface mount circuit, which is mounted on the output terminal of the high-side driver chip 21 that requires wire harness protection function.

[0092] In practical applications, not all scenarios require overheat protection for the high-side driver chip 21. This circuit exists independently of the high-side driver chip 21 and is a removable surface-mount circuit, making it easy to connect or remove. When overheat protection for the wire harness is required, this circuit is mounted at the output terminal of the corresponding high-side driver chip 21; otherwise, it can be left unmounted, offering greater flexibility and lower cost.

[0093] In the above embodiments, a wire harness overheat protection circuit has been described in detail. This application also provides an embodiment corresponding to a driving circuit. A driving circuit, including the wire harness overheat protection circuit provided in any of the above embodiments, can bring the same technical effects as the above-described wire harness overheat protection circuit embodiments. Since the embodiments of the driving circuit portion correspond to the embodiments of the wire harness overheat protection circuit portion, please refer to the description of the embodiments of the wire harness overheat protection circuit portion for the embodiments of the driving circuit portion, and will not be repeated here.

[0094] The above provides a detailed description of the wire harness overheat protection circuit and drive circuit provided by this utility model. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

[0095] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover 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 limitations, 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.

Claims

1. A wire harness overheat protection circuit, characterized in that, include: Self-resetting fuses, conversion modules, and detection and protection modules; The input terminal of the conversion module is connected to the output terminal of the high-side driver chip, and the output terminal of the conversion module is connected to the self-resetting fuse, for converting the first current signal output by the high-side driver chip into a second current signal output; wherein, the current value of the second current signal is less than that of the first current signal; The detection and protection module is connected to the resettable fuse and the enable terminal of the high-side driver chip, and is used to detect the state of the resettable fuse and invalidate the enable signal connected to the enable terminal of the high-side driver chip when the resettable fuse is in a protected state.

2. The wire harness overheat protection circuit according to claim 1, characterized in that, The conversion module includes: a data acquisition resistor, an amplifier circuit, and a conversion resistor; The acquisition resistor is connected in series at the output terminal of the high-side driver chip. The input terminal of the amplifier circuit is connected to both ends of the acquisition resistor. The output terminal of the amplifier circuit is connected to the first end of the resettable fuse. The second end of the resettable fuse is connected to the first end of the conversion resistor. The second end of the conversion resistor is grounded.

3. The wire harness overheat protection circuit according to claim 2, characterized in that, The conversion module further includes: a voltage follower circuit; The input terminal of the voltage follower circuit is connected to the output terminal of the amplifier circuit, and the output terminal of the voltage follower circuit is connected to the first terminal of the resettable fuse.

4. The wire harness overheat protection circuit according to claim 3, characterized in that, The conversion module further includes: a power switching transistor; The controlled terminal of the power switch is connected to the output terminal of the voltage follower circuit, the first terminal of the power switch is connected to the power supply, and the second segment of the power switch is connected to the first terminal of the resettable fuse.

5. The wire harness overheat protection circuit according to claim 2, characterized in that, The enable signal is a high-level signal; The detection and protection module includes: a switch module; The controlled terminal of the switching module is connected to the first terminal of the switching resistor, the first terminal of the switching module is connected to the enable terminal of the high-side driver chip, and the second terminal of the switching module is grounded. The switch module is turned off when a first detection signal is received, and turned on when a second detection signal is received; wherein, the first detection signal is the signal at the second end of the self-resetting fuse when the self-resetting fuse is in a normal state, and the second detection signal is the signal at the second end of the self-resetting fuse when the self-resetting fuse is in a protected state.

6. The wire harness overheat protection circuit according to claim 5, characterized in that, The enable signal is output by the enable control module; The first end of the switch module is also connected to the detection end of the enable control module; the enable control module stops outputting the enable signal when a low-level signal is received at the detection end.

7. The wire harness overheat protection circuit according to claim 5, characterized in that, The switching module includes: a first switching transistor and a second switching transistor; The controlled terminal of the first switching transistor is connected to the first terminal of the switching resistor, the second terminal of the first switching transistor is connected to the second terminal of the switching resistor, and the first terminal of the first switching transistor is connected to the controlled terminal of the second switching transistor. The first terminal of the second switch is connected to the enable terminal of the high-side driver chip, and the second terminal of the second switch is grounded.

8. The wire harness overheat protection circuit according to claim 7, characterized in that, The switching module further includes: a pull-up circuit; The pull-up circuit is connected to the first terminal of the first switching transistor.

9. The wire harness overheat protection circuit according to any one of claims 1 to 8, characterized in that, The overheat protection circuit for the wire harness is a removable surface mount circuit, which is mounted at the output of the high-side driver chip that requires wire harness protection.

10. A driving circuit, characterized in that, It includes the wire harness overheat protection circuit as described in any one of claims 1 to 9, and a high-side driver chip.

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