Signal transmission system, electronic control unit and short circuit protection circuit for interface driving circuit

Abstract

The application provides a signal transmission system, an electronic control unit and a short-circuit protection circuit of an interface driving circuit, relates to the technical field of electronic circuits, and the delay unit and the current limiting unit in the circuit are connected with the interface driving circuit; the interface driving circuit at least comprises a first switch tube, the current limiting unit is used for limiting the conduction current of the first switch tube within a first time, and the delay unit is used for controlling the duration of the first time; the starting point of the first time is the time point when the first switch tube is driven, the conduction current of the first switch tube within the first time is greater than the conduction current within other times, a higher current can be passed within the first time when the first switch tube is opened, the fast level conversion is completed to realize driving, and the conduction current of the first switch tube within other times is reduced; thus, even if a short circuit occurs, the thermal damage of a large current to an electrical appliance can be avoided, so that the short-circuit protection of the interface driving circuit is realized.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, specifically to a short-circuit protection circuit for a signal transmission system, an electronic control unit, and an interface driving circuit. Background Technology

[0002] In modern electronic systems, communication interfaces between different circuit boards play a crucial role. These interfaces enable multiple modules or devices to efficiently exchange data and control signals, thereby achieving complex functions and system integration.

[0003] Based on application requirements and design specifications, communication interfaces can be categorized into various types, each with its unique characteristics and applicable scenarios. For example, UART (Universal Asynchronous Receiver / Transmitter) and CAN (Controller Area Network) not only have their own communication protocols but also corresponding hardware chips to implement physical layer signal transmission.

[0004] Despite the variety of communication interfaces, digital I / O (Digital Input / Output) remains a common interface type in some simple communication applications with limited signal transmission. Interface short-circuit protection is a crucial safety measure in electronic device design, designed to prevent current overload caused by short-circuit faults, thereby protecting the normal operation of the interface driver circuit. Therefore, how to implement short-circuit protection for interface driver circuits is a pressing technical problem that needs to be solved. Utility Model Content

[0005] In response, this application provides a short-circuit protection circuit for a signal transmission system, an electronic control unit, and an interface driving circuit, which can shorten the time when a large current flows through the interface driving circuit, realize short-circuit protection of the interface driving circuit, and ensure the normal operation of the interface driving circuit.

[0006] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0007] The first aspect of this application discloses a short-circuit protection circuit for an interface driver circuit, including: a delay unit and a current limiting unit;

[0008] Both the delay unit and the current limiting unit are connected to the interface driving circuit.

[0009] The interface driving circuit includes at least a first switching transistor. The current limiting unit is used to limit the conduction current of the first switching transistor within a first time period. The delay unit is used to control the duration of the first time period. The conduction current of the first switching transistor within the first time period is greater than the conduction current within other time periods. The starting point of the first time period is the point at which the first switching transistor is driven.

[0010] Optionally, in the short-circuit protection circuit of the interface driving circuit described above, the interface driving circuit includes: the first switching transistor, the first resistor, and the first capacitor;

[0011] The base of the first switching transistor serves as the first terminal of the interface driving circuit, and is connected to the corresponding communication interface through the first terminal of the delay unit.

[0012] The collector of the first switching transistor is connected to one end of the first resistor and one end of the first capacitor, respectively, and the connection point is connected to the signal line;

[0013] The other end of the first resistor is connected to an external power supply;

[0014] The other end of the first capacitor is grounded;

[0015] The emitter of the first switching transistor serves as the second terminal of the interface driving circuit, connecting the second terminal of the delay unit and the first terminal of the current limiting unit.

[0016] Optionally, in the short-circuit protection circuit of the interface driver circuit described above, the driving mode of the interface driver circuit includes: low-side driving, high-side driving, or dual-side driving.

[0017] Optionally, in the short-circuit protection circuit of the interface driving circuit described above, the first switching transistor is a triode.

[0018] Optionally, in the short-circuit protection circuit of the interface driving circuit described above, the current limiting unit includes: a second resistor, one end of the second resistor serving as the first end of the current limiting unit, and the other end of the second resistor being grounded.

[0019] Optionally, in the short-circuit protection circuit of the interface driving circuit described above, the delay unit includes: a third resistor, a fourth resistor, a second capacitor, and a second switching transistor.

[0020] One end of the third resistor is connected to the corresponding communication interface; the other end of the third resistor is connected to the collector of the second switching transistor, and the connection point serves as the first end of the delay unit.

[0021] The base of the second switching transistor is connected to one end of the fourth resistor and one end of the second capacitor, respectively, and the emitter of the second switching transistor and the other end of the second capacitor are both grounded.

[0022] The other end of the fourth resistor serves as the second end of the delay unit.

[0023] Optionally, in the short-circuit protection circuit of the interface driving circuit described above, the second switching transistor is a triode.

[0024] The second aspect of this application discloses an electronic control unit, which includes at least an MCU, wherein the communication interface of the MCU is provided with a short-circuit protection circuit for the interface driving circuit as described in any of the claims of the first aspect.

[0025] The second aspect of this application discloses a signal transmission system, including: a sensor unit and an electronic control unit as disclosed in the second aspect;

[0026] The sensor unit and the electronic control unit share an external power supply.

[0027] The sensor unit and the electronic control unit are connected by a signal line.

[0028] Optionally, in the above-described signal transmission system, the sensor unit includes: a sensor chip, a fifth resistor, a sixth resistor, a third capacitor, and a fourth capacitor;

[0029] The power supply terminal of the sensor chip and one end of the fifth resistor are both connected to the external power supply.

[0030] The other end of the fifth resistor is connected to one end of the sixth resistor and one end of the third capacitor, respectively; the other end of the sixth resistor is connected to one end of the fourth capacitor and the output terminal of the sensor chip, respectively.

[0031] The other end of the third capacitor, the other end of the fourth capacitor, and the ground terminal of the sensing chip are all grounded.

[0032] The short-circuit protection circuit of the interface driver circuit provided in this application includes: a delay unit and a current limiting unit; both the delay unit and the current limiting unit are connected to the interface driver circuit; the interface driver circuit includes at least a first switching transistor, the current limiting unit is used to limit the conduction current of the first switching transistor in a first time period, and the delay unit is used to control the duration of the first time period. The starting point of the first time period is the time when the first switching transistor is driven. The conduction current of the first switching transistor in the first time period is greater than the conduction current in other time periods. It can pass a higher current in the short time when the first switching transistor is turned on (the first time period) to achieve rapid level conversion and complete the drive, and reduce the conduction current of the first switching transistor in other time periods. In this way, even if a short circuit occurs, it can avoid thermal damage to electrical appliances caused by large current, thereby achieving short-circuit protection for the interface driver circuit. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application 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 only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of an existing signal transmission system;

[0035] Figure 2 A schematic diagram of a short-circuit protection circuit for an interface driver circuit provided in an embodiment of this application;

[0036] Figure 3 A circuit diagram of a short-circuit protection circuit for an interface driver circuit provided in an embodiment of this application;

[0037] Figure 4 This is a schematic diagram of the structure of an electronic control unit provided in an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of a signal transmission system provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] First of all, it should be noted that the digital I / O interface is one of the most basic input and output interfaces in electronic systems. It is mainly used to process binary signals (0 and 1) and has the advantages of flexible communication protocols and simple hardware implementation.

[0041] The interface mentioned in this application may be a communication interface or a digital I / O interface; of course, it may also be other existing interfaces, all of which are within the protection scope of this application.

[0042] like Figure 1 As shown, the interface driver circuit corresponding to the communication interface in the Electronic Control Unit (ECU) is a typical low-side driver, driven by a switch connecting the signal line (DATA) and the ground line (GND). Figure 1 The switch is implemented using a transistor. When the switch is closed, DATA is pulled low by the switch, resulting in a "0". When the switch is open, the pull-up resistor R1 on DATA pulls DATA to VSUP, resulting in a "1". Figure 1 The sensor module on the right has the same structure, and the two sides are interconnected to enable bidirectional data transmission.

[0043] In practical applications, the drive circuit corresponding to the communication interface of the electronic control unit, in addition to Figure 1 In addition to the transmitting circuit shown, there is also a receiving circuit, but because the input impedance of the receiving circuit is very high and has no impact on the circuit analysis, it is not illustrated in this application.

[0044] Interface short-circuit protection is a crucial safety measure in electronic device design, designed to prevent current overload caused by short-circuit faults, thereby protecting the corresponding interface's drive circuit and the normal operation of related equipment. For digital I / O interfaces between different circuit boards, the drive circuits corresponding to the communication interfaces in electronic control units are generally implemented in the form of low-side drive, high-side drive, and dual-side drive. Since each method differs only in the location of the drive and shares a common implementation principle, this application will describe low-side drive as an example.

[0045] In other words, digital I / O interfaces also require short-circuit protection. Since the principle is the same, this application only takes digital I / O interfaces with low-side drive as the driving circuit as an example to analyze various short-circuit protection methods and their defects. Among them, for digital I / O interfaces with low-side drive as the driving circuit, the dangerous situation is that when short-circuited to the power supply, it can easily cause switch overload and damage.

[0046] This application provides a short-circuit protection circuit for an interface driver circuit, which can shorten the time when a large current flows through the interface driver circuit, realize short-circuit protection of the interface driver circuit, and ensure the normal operation of the interface driver circuit.

[0047] Please see Figure 2 The short-circuit protection circuit of the interface driver circuit mainly includes: a delay unit 103 and a current limiting unit 102;

[0048] Both the delay unit 103 and the current limiting unit 102 are connected to the interface driver circuit 101;

[0049] The interface driving circuit 101 includes at least a first switching transistor Q11, a current limiting unit 102 for limiting the conduction current of the first switching transistor Q11 within a first time period, and a delay unit 103 for controlling the duration of the first time period. The conduction current of the first switching transistor Q11 within the first time period is greater than the conduction current within other time periods. The starting point of the first time period is the point at which the first switching transistor Q11 is driven.

[0050] In practice, when the interface needs to send signals to the outside, the interface driver circuit 101 needs to be driven to establish a signal line connection path with the external device.

[0051] In some embodiments, such as Figure 2 As shown, the interface driving circuit may include: a first switching transistor Q11, a first resistor R11, and a first capacitor C11.

[0052] The base of the first switching transistor Q11 serves as the first terminal of the interface driving circuit 101, and is connected to the corresponding communication interface through the first terminal of the delay unit 103; the collector of the first switching transistor Q11 is connected to one end of the first resistor R11 and one end of the first capacitor C11, and the connection point is connected to the signal line DATA; the other end of the first resistor R11 is connected to the external power supply VSUP; the other end of the first capacitor C11 is grounded to GND; the emitter of the first switching transistor Q11 serves as the second terminal of the interface driving circuit 101, and is connected to the second terminal of the delay unit 103 and the first terminal of the current limiting unit 102.

[0053] In practical applications, the communication interface can be Figure 1 The MCU's output interface is powered by an external power source. Figure 1 VSUP.

[0054] When the first switch Q11 is in the ON state, the MCU's Output interface establishes a signal transmission channel with the external device; when the first switch Q11 is in the OFF state, the signal transmission channel between the MCU's Output interface and the external device is cut off.

[0055] In practice, the first switching transistor Q11 can be a bipolar transistor, that is... Figure 2 As shown; of course, it is not limited to this, and can also be other existing transistors. This application does not specifically limit them, and they are all within the protection scope of this application.

[0056] It should be noted that the first resistor R11 acts as a pull-up resistor in the interface driver circuit 101. When the first switch Q11 is in the off state, the collector voltage of the first switch Q11 is pulled up by the first resistor R11 to the voltage of the external power supply.

[0057] It should also be noted that in practice, the driving method of the interface driver circuit 101 can be any one of low-side driving, high-side driving, or dual-side driving, depending on the application environment and user requirements, and all of them are within the protection scope of this application.

[0058] In one embodiment, such as Figure 3 As shown, the current limiting unit 102 may include: a second resistor R12, one end of the second resistor R12 serving as the first end of the current limiting unit 102, and the other end of the second resistor R12 grounded to GND.

[0059] In practical applications, since the second resistor R12 is connected in series with the emitter of the first switching transistor Q11, the resistance value of the second resistor R12 is linearly related to the current flowing through the first switching transistor Q11 in the first time period. The current flowing through the first switching transistor Q11 in the first time period can be limited by adjusting the resistance value of the second resistor R12.

[0060] In one embodiment, such as Figure 3 As shown, the delay unit 103 may include: a third resistor R13, a fourth resistor R14, a second capacitor C12, and a second switch Q12;

[0061] One end of the third resistor R13 is connected to the corresponding communication interface; the other end of the third resistor R13 is connected to the collector of the second switch Q12, and the connection point serves as the first end of the delay unit 103; the base of the second switch Q12 is connected to one end of the fourth resistor R14 and one end of the second capacitor C12, respectively, and the emitter of the second switch Q12 and the other end of the second capacitor C12 are both grounded to GND; the other end of the fourth resistor R14 serves as the second end of the delay unit 103.

[0062] In practice, the second switching transistor Q12 can be a transistor; of course, it is not limited to this, and can also be other existing transistors. This application does not specifically limit it, and all of them are within the protection scope of this application.

[0063] In this application, the first time period can be the time between the start of charging of the second capacitor C12 and the start of conduction of the second switch Q12; other times can be the time periods during which the second switch Q12 is in the conduction state.

[0064] Combination Figure 3 Once the first switch Q11 is turned on, its emitter voltage is approximately equal to its collector voltage. At this time, the external power supply charges the second capacitor C12 through the first resistor R11, the first switch Q11, and the second resistor R12. The fourth resistor R14 and the second capacitor C12 form an RC circuit. When the base voltage of the second switch Q12 reaches its turn-on voltage, the interface drive circuit 101 enters other states. During these other states, both the second switch Q12 and the first switch Q11 are in the on state. The first switch Q11, the second switch Q12, the second resistor R12, the third resistor R13, and the fourth resistor R14 form a current-limiting circuit.

[0065] Due to the characteristics of a transistor, the voltage between its base and collector stabilizes within a small range, such as 0.7V, after the transistor is turned on. When the second capacitor C12 is fully charged and stable, the base voltage of the first switching transistor Q11 can be expressed as: V NET1 =V NET3 +0.7V=V NET2 +I BQ12 *R14+0.7V, where V NET2 =0.7V, I BQ12 It is the current flowing into the base of the second switching transistor Q12.

[0066] Assuming the MCU's communication interface outputs a stable 3.3V, then we have 3.3V - R13 * (β * I) BQ12 +I BQ11 )=V NET1 Among them, I BQ11 Let β be the base current of the first switching transistor Q11, and β be the amplification factor of the second switching transistor Q12. Since I... BQ11 Relative to β*I BQ12 It's very small, so it can be omitted.

[0067] Based on the above, the expression for the base current of the second switch Q12 can be obtained:

[0068] I BQ12 =1.9V / (R14+β*R13), V NET3 =0.7V+1.9V / (1+β*R13 / R14).

[0069] According to the expression for the base current of the second switch Q12, the current flowing through the first switch Q11 at other times is V. NET3 / R2+I BQ12 Therefore, the current flowing through the first switching transistor Q11 can be controlled by adjusting the second resistor R12, the third resistor R13, and the fourth resistor R14.

[0070] It is understandable that at other times, the current flowing through the first switching transistor Q11 can be controlled by freely adjusting the second resistor R12, the third resistor R13, and the fourth resistor R14.

[0071] It's important to note that the high current caused by a short circuit damages devices through thermal stress, meaning the device heats up and exceeds its tolerance range. Heat, or thermal energy, is a physical quantity that accumulates over time; its value is the product of thermal power and time. In a typical heating process, the temperature gradually increases until thermal equilibrium is reached. Therefore, the thermal power a device can withstand is also a time-dependent parameter; the shorter the time, the greater the thermal power the device can withstand.

[0072] Based on the above, the short-circuit protection circuit of the interface driving circuit provided in this application includes: a delay unit 103 and a current limiting unit 102; both the delay unit 103 and the current limiting unit 102 are connected to the interface driving circuit 101; the interface driving circuit 101 includes at least a first switching transistor Q11, the current limiting unit 102 is used to limit the conduction current of the first switching transistor Q11 in the first time period, and the delay unit 103 is used to control the duration of the first time period. The conduction current of the first switching transistor Q11 in the first time period is greater than the conduction current in other time periods. The starting point of the first time period is the time when the first switching transistor Q11 is driven. It can pass a higher current in the short time (first time period) when the first switching transistor Q11 is turned on to achieve rapid level conversion to complete the drive and reduce the conduction current of the first switching transistor Q11 in other time periods. In this way, even if a short circuit occurs, it can avoid the thermal damage to the electrical appliance caused by the large current, thereby realizing short-circuit protection for the interface driving circuit.

[0073] It is worth noting that when the interface driver circuit is in low-side drive mode, driving the first switching transistor Q11 requires pulling the signal line level down from "1" to "0". This process is actually a discharge of charge on the equivalent capacitance of the signal line, where the charge is the integral of the current over time. According to the relationship between charge and current, when the charge is constant, the larger the current, the shorter the discharge time. According to the definition of charge, under normal operating conditions, the charge on the equivalent capacitance is equal to the product of the capacitance and the voltage. For high-side drive, this process occurs when pulling the signal line down from "0" to "1", which is a charging process. Since the charging and discharging of a capacitor is a completely reversible process, the principle is the same. When the interface driver circuit uses the short-circuit protection circuit provided in this application, the time during which the first switching transistor carries a large current can be shortened. That is, the first switching transistor Q11 is allowed to carry a large current during the first time, and only a small current is allowed during other times. This way, even if a short circuit occurs, thermal damage to the electrical appliance caused by the large current can be avoided, thereby achieving short-circuit protection for the interface driver circuit.

[0074] Compared to existing short-circuit protection methods that improve the overcurrent capacity of components, the components used in the interface driver circuit of digital I / O interfaces have relatively small overcurrent capacity due to the relatively small operating current. Although using devices with greater overcurrent capacity, such as low-current drive chips for power supply, can significantly improve the tolerance to large currents, this leads to performance waste and increased costs. At the same time, devices with greater overcurrent capacity also require larger sizes and more layout restrictions. In contrast, the short-circuit protection circuit of the interface driver circuit provided in this application is not only simple in structure, but also requires conventional components, does not lead to performance waste, and has lower costs.

[0075] Compared to existing monitoring measures that monitor for short-circuit events and switch the switch path when a short circuit occurs, this application offers a different approach. Monitoring measures can be categorized as software or hardware monitoring, both requiring additional monitoring circuitry and increasing costs. Software monitoring involves the main control chip (such as an MCU) acquiring relevant physical quantities and using software logic to determine if a short circuit has occurred, controlling the switch's on / off state via software. This method relies on software execution, increasing software load, leading to sluggish software operation and poor real-time protection. Furthermore, performance deteriorates with the number of communication interfaces. While higher-performance main control chips can be used for optimization, this still increases costs. Hardware monitoring, while not relying on software control, uses hardware circuitry for all logic judgments and control, increasing circuit complexity and cost. In contrast, the short-circuit protection circuit of the interface driver circuit provided in this application achieves short-circuit protection using only simple components, offering high real-time protection at a lower cost.

[0076] Compared to existing current-limiting measures, this method limits the maximum current to prevent overload under short-circuit conditions. The most common current-limiting measure is the use of current-limiting resistors, such as... Figure 1 The resistor R3 in the diagram. Due to the communication requirements of the digital I / O interface, when the switching transistor Q1 is turned on, the collector voltage of the switching transistor should be as close to 0 level as possible, that is, the voltage at point NETI in the diagram should be close to 0 level. This is because if the collector voltage of the switching transistor is too high, the voltage of the logic "0" potential will be too high, which may cause level recognition errors. Based on this, it can be seen that when a short circuit to the power supply occurs, after adding the resistor, the voltage across it is close to the short circuit voltage, the current is close to U / R, and almost all the energy is absorbed by the resistor, with the resistor power being U2 / R.

[0077] Resistors have a limited power handling capacity; excessive power can burn them out. There are two main solutions to this problem. The first is to use resistors with very large packages that can handle high power, or to use multiple resistors in parallel to shunt the current, reducing the power of each individual resistor. The biggest problem with this method is the large size of the device, limiting its use in compact applications, especially when multiple interfaces are used simultaneously. The other method is to increase the resistor value, which reduces the power handling capacity, even with smaller packages. This method has two main drawbacks: First, when the output is "0" (i.e., the switch is on), the current-limiting resistor and the pull-up resistor will divide the voltage, causing the signal line voltage to be too high, potentially leading to misinterpretations. Second, because the current through the switch is very small, when the capacitance to ground of the signal line is large (including actively added EMC capacitance and parasitic capacitance of the connecting wires), the time for the signal line to transition from high to low will be relatively long. This process is equivalent to RC discharge, causing waveform distortion.

[0078] The short-circuit protection circuit of the interface driver circuit provided in this application does not require a large current-limiting resistor or an increase in the resistance value. It only requires a current-limiting resistor to be set at the emitter and base of the switching transistor. By controlling the time for the first switching transistor to carry a large current through a delay circuit, short-circuit protection can be achieved. This not only reduces the cost but also reduces the area occupied by the circuit.

[0079] Based on the above, another embodiment of this application also provides an electronic control unit, such as... Figure 4 As shown, the electronic control unit is at least MCU201, and the communication interface of MCU201 is provided with a short-circuit protection circuit 202 for the interface driving circuit as described in any of the above embodiments.

[0080] It should be noted that the electronic control unit can be a system in the field of automotive electronics, such as engine control system, transmission control, body electronic system, battery management system, vehicle control system, intelligent driving system, etc.; or it can be a system in the fields of industrial automation, aerospace, consumer electronics, etc., such as programmable logic control system, motor drive control system, process control system, flight control system, avionics system, smart home system, and medical equipment system, etc.; it can be determined according to the application environment and user needs, and all of them are within the scope of protection of this application.

[0081] It should also be noted that the relevant description of the short-circuit protection circuit 202 of the interface driver circuit can be found in the above embodiments, and the relevant description of the electronic control unit can be found in the prior art, which will not be repeated here.

[0082] Optionally, another embodiment of this application also provides a signal transmission system, such as... Figure 5 As shown, it mainly includes: a sensor module and an electronic control unit (ECU) as described in the above embodiments;

[0083] The sensor module and the electronic control unit (ECU) share an external power supply, VSUP.

[0084] The sensor module is connected to the electronic control unit (ECU) via signal lines.

[0085] In one embodiment, see also Figure 5 The sensor module may include: a sensor chip (SENSOR IC), a fifth resistor (R21), a sixth resistor (R22), a third capacitor (C21), and a fourth capacitor (C22).

[0086] The power supply terminal of the sensor chip SENSOR IC and one end of the fifth resistor R21 are both connected to the external power supply VSUP; the other end of the fifth resistor R21 is connected to one end of the sixth resistor R22 and one end of the third capacitor C21, and the other end of the sixth resistor R22 is connected to one end of the fourth capacitor C22 and the output terminal of the sensor chip SENSOR IC; the other ends of the third capacitor C21, the other ends of the fourth capacitor C22, and the ground terminal of the sensor chip SENSOR IC are all grounded.

[0087] In practical applications, the sensor IC includes a logic unit and a switching transistor Q21. The logic unit controls the state of the switching transistor Q21 to determine whether a transmission channel is established between the sensor module and the electronic control unit (ECU). Specifically, when the switching transistor Q21 in the sensor IC is in the ON state, the transmission channel between the sensor module and the ECU is established; when the switching transistor Q21 in the sensor IC is in the OFF state, the transmission channel between the sensor module and the ECU is disconnected.

[0088] It should be noted that the fifth resistor R21 is a pull-up resistor, and the sixth resistor R22, the third capacitor C21, and the fourth capacitor C22 can form an RC circuit.

[0089] It should also be noted that the relevant descriptions of the electronic control unit (ECU) can be found in the above embodiments, and the relevant descriptions of the signal transmission system can be found in the prior art, which will not be repeated in this application.

[0090] 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.

[0091] 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 application.

[0092] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. 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 this application. Therefore, this application 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.

[0093] It should also be noted that, in this document, 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 short-circuit protection circuit for an interface driver circuit, characterized in that, include: Delay unit and current limiting unit; Both the delay unit and the current limiting unit are connected to the interface driving circuit. The interface driving circuit includes at least a first switching transistor. The current limiting unit is used to limit the conduction current of the first switching transistor within a first time period. The delay unit is used to control the duration of the first time period. The conduction current of the first switching transistor within the first time period is greater than the conduction current within other time periods. The starting point of the first time period is the point at which the first switching transistor is driven.

2. The short-circuit protection circuit of the interface driver circuit according to claim 1, characterized in that, The interface driving circuit includes: the first switching transistor, the first resistor, and the first capacitor; The base of the first switching transistor serves as the first terminal of the interface driving circuit, and is connected to the corresponding communication interface through the first terminal of the delay unit. The collector of the first switching transistor is connected to one end of the first resistor and one end of the first capacitor, respectively, and the connection point is connected to the signal line; The other end of the first resistor is connected to an external power supply; The other end of the first capacitor is grounded; The emitter of the first switching transistor serves as the second terminal of the interface driving circuit, connecting the second terminal of the delay unit and the first terminal of the current limiting unit.

3. The short-circuit protection circuit of the interface driver circuit according to claim 2, characterized in that, The interface driver circuit can be driven in the following ways: low-side driving, high-side driving, or dual-side driving.

4. The short-circuit protection circuit of the interface driver circuit according to claim 3, characterized in that, The first switching transistor is a triode.

5. The short-circuit protection circuit of the interface driver circuit according to claim 1, characterized in that, The current limiting unit includes a second resistor, one end of which serves as the first end of the current limiting unit, and the other end of which is grounded.

6. The short-circuit protection circuit of the interface driver circuit according to claim 1, characterized in that, The delay unit includes: a third resistor, a fourth resistor, a second capacitor, and a second switching transistor; One end of the third resistor is connected to the corresponding communication interface; the other end of the third resistor is connected to the collector of the second switching transistor, and the connection point serves as the first end of the delay unit. The base of the second switching transistor is connected to one end of the fourth resistor and one end of the second capacitor, respectively, and the emitter of the second switching transistor and the other end of the second capacitor are both grounded. The other end of the fourth resistor serves as the second end of the delay unit.

7. The short-circuit protection circuit of the interface driver circuit according to claim 6, characterized in that, The second switching transistor is a triode.

8. An electronic control unit, characterized in that, It includes at least an MCU, and the communication interface of the MCU is provided with a short-circuit protection circuit for the interface driving circuit as described in any one of claims 1-7.

9. A signal transmission system, characterized in that, include: The sensor unit and the electronic control unit as described in claim 8; The sensor unit and the electronic control unit share an external power supply. The sensor unit and the electronic control unit are connected by a signal line.

10. The signal transmission system according to claim 9, characterized in that, The sensor unit includes: a sensor chip, a fifth resistor, a sixth resistor, a third capacitor, and a fourth capacitor; The power supply terminal of the sensor chip and one end of the fifth resistor are both connected to the external power supply. The other end of the fifth resistor is connected to one end of the sixth resistor and one end of the third capacitor, respectively; the other end of the sixth resistor is connected to one end of the fourth capacitor and the output terminal of the sensor chip, respectively. The other end of the third capacitor, the other end of the fourth capacitor, and the ground terminal of the sensing chip are all grounded.

Images