Serial communication bus transceiver circuit and vehicle-mounted communication system

Abstract

The application provides a serial communication bus transceiver circuit and a vehicle-mounted communication system, the serial communication bus transceiver circuit comprising: a signal input module for accessing a serial input signal to obtain a serial optimization signal; a signal interaction module for outputting a serial level signal to the micro control module; the micro control module is used for collecting and storing the serial level signal in a signal collection state, and outputting a sending signal in a signal output state; a switch control module for outputting a serial output signal to a serial bus according to the sending signal and a power supply; when the signal interaction module does not detect the serial optimization signal, the signal interaction module and the switch control module stop working. When the serial optimization signal is not detected, the signal interaction module and the signal work are terminated, the static power consumption of the bus in the idle state is reduced while the signal input and output are realized, and the comprehensive requirements of low static current, low cost and high reliability are met.

Description

Technical Field

[0001] This invention relates to the field of bus communication technology, and more particularly to a serial communication bus transceiver circuit and an in-vehicle communication system. Background Technology

[0002] LIN (Local Interconnect Network) bus is a low-cost serial communication protocol based on UART / SCI (Universal Asynchronous Receiver-Transmitter / Serial Communication Interface), widely used in automotive electronic units such as body control modules, window regulators, seat adjusters, rain sensors, and actuators. As an effective complement to the CAN (Controller Area Network) bus, LIN bus has gained widespread application in automotive internal control systems due to its advantages such as low implementation cost and simple connection.

[0003] However, in the bus idle state, the voltage divider resistors or pull-up resistor branches in traditional discrete solutions continuously consume current, resulting in a large quiescent current. For automotive-grade applications, the body control module typically requires a quiescent current in the microampere range to meet the low-power standby requirements of the battery, which existing discrete solutions struggle to achieve. To address this, some existing technologies employ dedicated transceiver chips. While these chips can meet the automotive-grade low quiescent current requirements, they are costly, making it difficult for existing technologies to simultaneously meet the comprehensive requirements of low quiescent current, low cost, and high reliability.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a serial communication bus transceiver circuit and an in-vehicle communication system to solve the problems of high static current and high static power consumption of existing serial communication bus transceiver circuits, which make it difficult to meet the automotive-grade low static current requirements under limited cost.

[0006] The technical solution of the present invention is as follows: This invention provides a serial communication bus transceiver circuit for connection to a microcontroller module, comprising: The signal input module is connected to the serial bus and is used to receive serial input signals and perform signal processing to obtain serial optimized signals. A signal interaction module, connected to the signal input module and the microcontroller module, is used to perform level conversion on the serial optimized signal and output a serial level signal to the microcontroller module; the microcontroller module is used to acquire and store the serial level signal in signal acquisition mode, and to output a transmission signal to the signal interaction module in signal output mode; the signal interaction module is used to output the transmission signal. A switch control module, connected to the signal interaction module and connected to a power supply, is used to collect the transmitted signal output by the signal interaction module, and output a serial output signal to the signal interaction module according to the transmitted signal and the power supply. The serial output signal is output to a serial bus through the signal interaction module. When the signal interaction module does not detect the serial optimization signal, the signal interaction module and the switch control module stop working.

[0007] In a further embodiment of the present invention, the signal input module includes a voltage divider unit and a filter unit. One end of the voltage divider unit is used to receive a serial input signal and to divide the serial input signal to obtain a serial voltage-divided signal. The filtering unit is connected to the voltage divider unit and is used to filter the serial voltage divider signal and output a serial optimized signal to the signal interaction module.

[0008] In a further embodiment of the present invention, the voltage divider unit includes: a first resistor, a first ferrite bead, and a second resistor; wherein, One end of the first resistor is connected to a pull-up power supply, the other end of the first resistor is connected to a serial bus and to one end of the first ferrite bead, the other end of the first ferrite bead is connected to one end of the second resistor, and the other end of the second resistor is connected to the signal interaction module.

[0009] In a further embodiment of the present invention, the filtering unit includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the common terminal of the first resistor and the first ferrite bead, and the other end of the first capacitor is grounded. One end of the second capacitor is connected to the common terminal of the first ferrite bead and the second resistor, and the other end of the second capacitor is grounded.

[0010] In a further embodiment of the present invention, the signal interaction module includes: a third resistor, a first switching transistor, a first diode, and a fourth resistor; wherein, One end of the third resistor is connected to the signal input module, and the other end of the third resistor is connected to the base of the first switching transistor; the base of the first switching transistor is connected to the switch control module, and the emitter of the first switching transistor is connected to the common terminal of the third resistor and the signal input module; the collector of the first switching transistor is connected to the microcontroller module. The anode of the first switching transistor and one end of the fourth resistor are connected to the emitter of the first switching transistor, and the cathode of the first switching transistor and the other end of the fourth resistor are connected to the collector of the first switching transistor and the common terminal of the microcontroller module.

[0011] In a further embodiment of the present invention, the switch control module includes: a drive control unit and a base bias voltage regulator unit; wherein, The drive control unit is connected to the power supply and is connected to the base bias voltage regulator and the signal interaction module. It is used to collect the transmitted signal. The transmitted signal is used to control the drive control unit to turn on and off. The drive control unit outputs the on / off signal to the base bias voltage regulator. The base bias voltage regulator unit is connected to the power supply and is used to output the serial output signal to the drive control unit according to the on / off signal; the drive control unit is used to output the serial output signal to the signal interaction module.

[0012] A further embodiment of the present invention includes a switching filter unit, wherein the switching filter unit includes a third capacitor, one end of the third capacitor is connected to the drive control unit, and the other end of the third capacitor is grounded.

[0013] In a further embodiment of the present invention, the drive control unit includes: a fifth resistor and a second switching transistor, one end of the fifth resistor is connected to the signal interaction module and connected to a power supply, the other end of the fifth resistor is connected to the emitter of the second switching transistor, and the base and emitter of the second switching transistor are connected to the base bias voltage regulator unit.

[0014] In a further embodiment of the present invention, the base bias voltage regulator unit includes: a sixth resistor, a seventh resistor, an eighth resistor, a second diode, and a first Zener diode; wherein, One end of the sixth resistor is connected to the path terminal of the drive control unit, and the other end of the sixth resistor is connected to the power supply voltage. One end of the seventh resistor is connected to the power supply voltage, and the other end of the seventh resistor and the anode of the second diode are connected to the control terminal of the drive control unit. The cathode of the second diode is connected to the cathode of the first Zener diode, and the anode of the first Zener diode is grounded. One end of the eighth resistor is connected to the common terminal of the seventh resistor and the drive control unit, and the other end of the eighth resistor is connected to the common terminal of the cathode of the second diode and the anode of the first Zener diode.

[0015] Based on the same inventive concept, an in-vehicle communication system is also provided, which includes the serial communication bus transceiver circuit described above, at least one body control module, at least one sensing and detection module, and at least one execution module; the body control module, the sensing and detection module, and the execution module are respectively connected to the serial bus and are used to output serial input signals to the serial bus and collect serial output signals on the serial bus.

[0016] This invention provides a serial communication bus transceiver circuit and an in-vehicle communication system. The serial communication bus transceiver circuit is used to connect to a microcontroller module and includes: a signal input module connected to a serial bus for receiving and processing serial input signals to obtain a serial optimized signal; a signal interaction module connected to the signal input module and the microcontroller module for level conversion of the serial optimized signal and outputting a serial level signal to the microcontroller module; the microcontroller module, in signal acquisition mode, acquires and stores the serial level signal, and in signal output mode, outputs a transmission signal to the signal interaction module; the signal interaction module outputs the transmission signal; a switch control module connected to the signal interaction module and connected to a power supply, for acquiring the transmission signal output by the signal interaction module and outputting a serial output signal to the signal interaction module based on the transmission signal and the power supply, the serial output signal being output to the serial bus through the signal interaction module; when the signal interaction module does not detect the serial optimized signal, the signal interaction module and the switch control module stop working. This invention achieves input and output through a signal interaction module. When serial input is achieved, the serial input signal is processed by the signal input module. When serial output is achieved, the signal is modulated by the switch control module. When the serial optimization signal is not detected, the signal interaction module and signal operation are terminated. This achieves signal input and output while reducing the static power consumption when the bus is idle, thus meeting the comprehensive requirements of low static current, low cost, and high reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the serial communication bus transceiver circuit in this invention.

[0019] Figure 2This is a circuit diagram of the serial communication bus transceiver circuit in this invention.

[0020] The labels in the attached diagram are as follows: 100, signal input module; 110, voltage divider unit; 120, filter unit; 200, signal interaction module; 300, switch control module; 310, drive control unit; 320, base bias voltage regulator unit; 1, microcontroller module. Detailed Implementation

[0021] This invention provides a serial communication bus transceiver circuit and an in-vehicle communication system. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of the present invention involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0023] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0024] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0025] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0026] LIN bus is a low-cost serial communication standard for automotive applications, widely used in body control modules, sensors, and actuators. Conventional LIN bus interfaces typically employ dedicated transceiver chips or discrete circuits to implement signal transmission and reception and level conversion. Currently, the primary implementation scheme for LIN bus interfaces uses dedicated transceiver chips. This scheme utilizes commercially available dedicated LIN transceiver chips to implement physical layer signal transmission and reception and level conversion. These chips typically integrate ESD (Electro-Static Discharge) protection, slope control, overheat protection, and low-power modes, offering stable and reliable performance. However, dedicated transceiver chips have higher material costs. Furthermore, for cost-sensitive applications or those with specific customization requirements, the dedicated chip solution lacks flexibility.

[0027] The inventors discovered that, in addition to the above-mentioned shortcomings of existing LIN bus transceiver circuits implemented with discrete components, the following also apply: When the bus is idle, the voltage divider resistors or pull-up resistors in traditional discrete solutions continuously consume current, resulting in a large quiescent current. For automotive-grade applications, the body control module typically requires a quiescent current in the microamplitude range to meet the low-power standby requirements of the battery, which existing discrete solutions struggle to achieve effectively, leading to high quiescent power consumption.

[0028] The automotive electromagnetic environment is complex, and the LIN bus may couple with common-mode noise and radiated interference from sources such as the ignition system and motor commutator. Existing discrete solutions often only implement simple RC filters for electromagnetic interference (EMI) filtering and electrostatic discharge protection, lacking a systematic multi-level protection architecture. This leads to decreased communication reliability and insufficient anti-interference capability in the complex automotive electromagnetic environment.

[0029] Existing discrete transceiver circuits lack targeted optimization design for the steepness of bus signal edges and level matching, resulting in obvious signal edge overshoot or ringing, which can easily cause misjudgment at the receiver, leading to an increase in the communication bit error rate, affecting the stability of LIN bus communication, and having weak signal conditioning capabilities.

[0030] Dedicated transceiver chips offer excellent performance but are expensive, making it difficult to improve dedicated transceivers within limited processing costs. Existing discrete solutions, while cost-effective, suffer from high power consumption, insufficient interference immunity, and poor signal integrity, making it difficult to simultaneously meet automotive-grade requirements for low quiescent current, high interference immunity, and high reliability.

[0031] In summary, there is an urgent need in the existing technology for a discrete LIN bus transceiver and signal conditioning circuit that can balance low quiescent current, high anti-interference capability, excellent signal integrity, and low cost.

[0032] To solve the technical problems existing in the current technology, such as Figure 1 As shown, this invention provides a serial communication bus transceiver circuit for connection to a microcontroller module 1, comprising: a signal input module 100 connected to a serial bus for receiving and processing serial input signals to obtain a serial optimized signal; and a signal interaction module 200 connected to the signal input module 100 and the microcontroller module 1 for level conversion of the serial optimized signal and outputting a serial level signal to the microcontroller module 1; the microcontroller module 1, in signal acquisition mode, acquires and stores the serial level signal, and in signal output mode, outputs a transmission signal to the microcontroller module 1. The signal interaction module 200 is used to output the transmitted signal. The switch control module 300 is connected to the signal interaction module 200 and connected to a power supply VS. It is used to collect the transmitted signal output by the signal interaction module 200 and output a serial output signal to the signal interaction module 200 based on the transmitted signal and the power supply VS. The serial output signal is output to a serial bus through the signal interaction module 200. When the signal interaction module 200 does not detect the serial optimization signal, both the signal interaction module 200 and the switch control module 300 stop working.

[0033] The serial bus can be a LIN bus or other serial buses, such as CAN bus, FlexRay bus, MOST (Media Oriented Systems Transport) bus, or Ethernet, etc. Specifically, the serial bus is connected to the serial communication bus transceiver circuit and can be used to transmit serial input signals to the serial communication bus transceiver circuit or receive serial output signals from the serial communication bus transceiver circuit. The signal input module 100 is used to implement the front-end preprocessing function of the bus signal. When the serial bus starts to input a serial input signal, the signal input module 100 performs signal processing on the serial input signal. Optionally, it can be used to perform signal processing procedures such as input filtering, current limiting protection, and resistor voltage division on the serial input signal to obtain a serial optimized signal. The signal interaction module 200 is connected to the microcontroller module 1. When the serial optimized signal is received, the signal interaction module 200 selects to turn on or off according to the serial optimized signal, thereby converting the input serial optimized signal into a serial level signal suitable for the microcontroller module 1 to receive. The microcontroller module 1 operates in the signal acquisition state. Correspondingly, when the microcontroller module 1 is in the signal output state, it outputs a transmission signal. The transmission signal controls the switch control module 300 according to the on / off state of the signal interaction module 200. The signal interaction module 200 controls the on / off state of the signal interaction module 200 according to the transmission signal and the power supply VS. Thus, through the transmission signal output by the microcontroller module 1 and the switch control module 300, the serial output signal output by the signal interaction module 200 to the signal input module 100 and transmitted to the serial bus through the signal input module 100 can be controlled.

[0034] Specifically, when the microcontroller module 1 outputs a transmission signal, the signal interaction module 200 is turned on and outputs the transmission signal to the switch control module 300; the switch control module 300 outputs a serial output signal to the signal interaction module 200 according to the transmission signal, and the serial output signal is output to the serial bus through the signal interaction module 200.

[0035] In some preferred embodiments, the signal input module 100 includes a voltage divider unit 110 and a filter unit 120. One end of the voltage divider unit 110 is used to receive a serial input signal and to divide the serial input signal to obtain a serial voltage-divided signal. The filter unit 120 is connected to the voltage divider unit 110 and is used to filter the serial voltage-divided signal and output a serial optimized signal to the signal interaction module 200.

[0036] Specifically, the voltage divider unit 110 receives the serial input signal and is used to divide the serial input signal while providing current limiting protection. Optionally, a pull-up power supply KL30 can also be connected to the voltage divider unit 110 to pull the port of the voltage divider unit 110 high in the default state. When the serial communication bus transceiver circuit is working, the serial input signal from the serial bus is first connected to the voltage divider unit 110. The voltage divider unit 110 uses a resistor network to perform voltage division and overcurrent limiting on the high-voltage serial signal on the bus side, adjusting the signal amplitude to match the input range of the subsequent transistor circuit to generate a serial voltage-divided signal. Subsequently, the serial voltage-divided signal is input to the filter unit 120 connected to the voltage divider unit 110 for filtering. Optionally, the filter unit 120 can be implemented using a multi-stage EMI filter architecture composed of ferrite beads and capacitors to filter out high-frequency electromagnetic interference and transient noise spikes carried in the signal, and output a serial optimized signal to the signal interaction module 200 to provide a reliable signal for signal level conversion and transmission in the subsequent circuit.

[0037] Please refer to the following: Figure 1 and Figure 2 In a further preferred embodiment of the present invention, the voltage divider unit 110 includes: a first resistor R1, a first ferrite bead FB1, and a second resistor R2; wherein, one end of the first resistor R1 is connected to a pull-up power supply KL30, the other end of the first resistor R1 is connected to a serial bus and to one end of the first ferrite bead FB1, the other end of the first ferrite bead FB1 is connected to one end of the second resistor R2; and the other end of the second resistor R2 is connected to the signal interaction module 200.

[0038] Specifically, the pull-up power supply KL30 is the power pull-up terminal, and the first resistor R1 is a standard pull-up resistor for the serial bus. Optionally, the resistance value of the first resistor R1 can be 2.2KΩ. The second resistor R2 is connected in series in the signal transmission path of the serial bus to implement overcurrent limiting protection, prevent abnormal bus current from damaging subsequent circuits, and output a serial optimization signal. The first ferrite bead FB1, based on the impedance frequency characteristics of ferrite material, presents high impedance to high-frequency interference signals coupled in the complex electromagnetic environment of the vehicle, and achieves attenuation and suppression by converting high-frequency interference energy into heat energy, thereby achieving bidirectional suppression of electromagnetic interference. Optionally, the first ferrite bead FB1 can be a 600Ω ferrite bead. Furthermore, in some preferred embodiments, the resistance values ​​of the first resistor R1, the third resistor R3, the fifth resistor R5, etc., can be adjusted according to the serial bus voltage range to adapt to different serial bus voltages and the operating level of the microcontroller module 1. Optionally, the serial bus voltage is 12V.

[0039] In some preferred embodiments, the filtering unit 120 includes a first capacitor C1 and a second capacitor C2. One end of the first capacitor C1 is connected to the common terminal of the first resistor R1 and the first ferrite bead FB1, and the other end of the first capacitor C1 is grounded. One end of the second capacitor C2 is connected to the common terminal of the first ferrite bead FB1 and the second resistor R2, and the other end of the second capacitor C2 is grounded. The first capacitor C1 and the second capacitor C2 are serial bus ground filtering capacitors, realizing basic anti-interference processing of bus signals. At the same time, the first capacitor C1, the second capacitor C2, and the first ferrite bead FB1 together form a multi-stage LC filtering network to filter out high-frequency EMI interference, providing a low-impedance ground discharge path for high-frequency electromagnetic interference noise coupled in the signals transmitted by the serial bus, so that high-frequency interference is directly introduced into the ground plane without being conducted to the subsequent transceiver circuit. Without affecting the DC level of the serial bus and the normal low-speed data signal transmission, it effectively filters out high-frequency interference introduced by the complex electromagnetic environment of the vehicle, and optimizes the waveform quality of the bus signal.

[0040] Further, the signal interaction module 200 includes: a third resistor R3, a first switch Q1, a first diode D1, and a fourth resistor R4; wherein, one end of the third resistor R3 is connected to the signal input module 100, and the other end of the third resistor R3 is connected to the base of the first switch Q1; the base of the first switch Q1 is connected to the switch control module 300, and the emitter of the first switch Q1 is connected to the common terminal of the third resistor R3 and the signal input module 100; the collector of the first switch Q1 is connected to the microcontroller module 1; the anode of the first switch Q1 and one end of the fourth resistor R4 are connected to the emitter of the first switch Q1, and the cathode of the first switch Q1 and the other end of the fourth resistor R4 are connected to the common terminal of the collector of the first switch Q1 and the microcontroller module 1.

[0041] Specifically, the serial input signal is current-limited by the second resistor R2 of the signal input module 100 to obtain a serial optimized signal. When the serial optimized signal is input to the signal interaction module 200, it is input to the base circuit of the first switching transistor Q1. Optionally, the first switching transistor Q1 is an NPN transistor used to convert the high-voltage domain signal on the serial bus into a low-voltage domain signal recognizable by the microcontroller module 1. The third resistor R3 is a base current-limiting resistor. Optionally, the resistance of the third resistor R3 is 10KΩ, used to precisely control the current injected into the base of the first switching transistor Q1, which avoids base current overload causing transistor damage and optimizes the edge characteristics of signal conduction and turn-off, improving signal waveform quality. The first diode D1 is connected in reverse parallel between the collector and emitter of the first switching transistor Q1 to achieve signal clamping and electrostatic discharge, preventing overvoltage damage to the transistor during operation.

[0042] The emitter of the first switching transistor Q1 is connected to the microcontroller module 1 via a fourth resistor R4. Optionally, the fourth resistor R4 can be a 10Ω resistor. The collector of the first switching transistor Q1 is connected to the LIN_MCU pin of the microcontroller module 1 for the microcontroller module 1 to read the serial level signal. When the serial bus is high, the first switching transistor Q1 is turned off because the forward bias voltage of the emitter junction is less than the threshold. At this time, no main circuit current flows through the fourth resistor R4, and the collector of the first switching transistor Q1 is pulled up and maintained at a high level. At this time, the level output to the LIN_MCU pin of the microcontroller module 1 is high. At the same time, the first diode D1 is turned off due to reverse bias. When the serial bus is low, the emitter of the first switching transistor Q1 receives sufficient forward bias and enters the saturation conduction state, the collector is pulled low, and the level output to the LIN_MCU pin of the microcontroller module 1 is low. This realizes the conversion of the serial optimized signal input from the serial bus to the input level of the microcontroller module 1. Meanwhile, the fourth resistor R4 is used to limit the emitter current amplitude, stabilize the static operating point of the first switching transistor Q1, suppress current spikes during switching, and optimize the smoothness of signal edges. When the circuit encounters transient overvoltage or electrostatic discharge impact, the first diode D1 quickly forward conducts, clamping the voltage across the collector and emitter of the first switching transistor Q1 within a predetermined safety threshold, thereby quickly dissipating abnormal energy and preventing the first switching transistor Q1 from being damaged by overvoltage breakdown.

[0043] Further, the switch control module 300 includes: a drive control unit 310 and a base bias voltage regulator unit 320; wherein, the drive control unit 310 is connected to the power supply VS and is connected to the base bias voltage regulator unit 320 and the signal interaction module 200, for acquiring the transmitted signal, the transmitted signal being used to control the drive control unit 310 to turn on and off, and the drive control unit 310 outputs an on / off signal to the base bias voltage regulator unit 320; the base bias voltage regulator unit 320 is connected to the power supply VS and is used to output the serial output signal to the drive control unit 310 according to the on / off signal; the drive control unit 310 is used to output the serial output signal to the signal interaction module 200.

[0044] The drive control unit 310, during operation, acquires the transmitted signal output by the microcontroller module 1 through the signal interaction module 200, and simultaneously connects to the power supply VS, which provides voltage for the entire control loop. The drive control unit 310 controls the conduction and cutoff states of its internal bias path based on the level changes of the transmitted signal, thereby obtaining corresponding on / off signals. The base bias regulator unit 320 is connected to the power supply VS, constructs a stable bias voltage reference based on VS, and adjusts its internal output bias level and generates a serial output signal upon receiving the on / off signal transmitted by the drive control unit 310. The serial output signal is fed back to the drive control unit 310, which then outputs the processed serial output signal to the signal interaction module 200, and subsequently to the serial bus via the signal interaction module 200 and signal input module 100, thus completing the level conversion of the transmitted signal and drive control. This process effectively suppresses power fluctuations and clamping transient high-voltage interference, ensuring the accuracy of drive control and the reliability of signal output under wide voltage conditions in the vehicle.

[0045] The drive control unit 310 includes a fifth resistor R5 and a second switch Q2. One end of the fifth resistor R5 is connected to the signal interaction module 200 and connected to the power supply VS. The other end of the fifth resistor R5 is connected to the emitter of the second switch Q2. The base and emitter of the second switch Q2 are connected to the base bias voltage regulator unit 320.

[0046] Specifically, during operation, the LIN_MCU pin of the microcontroller module 1 outputs a transmit signal. This transmit signal is first divided and current-limited by the fifth resistor R5. The fifth resistor R5 is used to limit the current injected into the base of the second switch Q2 in the subsequent circuit, preventing overload damage to the device. Subsequently, the transmit signal is input to the base circuit of the second switch Q2. Optionally, the second switch Q2 is an NPN transistor. The second switch Q2 is used to control the serial bus level pull-down and release, and to drive signal transmission. When the transmit signal of the microcontroller module 1 is a low-level signal, the base of the second switch Q2 receives a sufficient forward bias voltage after being divided and controlled by the fifth resistor R5, and the second switch Q2 remains in a saturated conduction state. At this time, a low-impedance path to ground is formed between the serial bus and the low-level LIN_MCU pin of the microcontroller module 1, and the bus is then pulled low. When the microcontroller module 1 sends a high-level signal, the base forward bias voltage of the second switch Q2 is less than the threshold voltage, thus remaining in the off state. The drive path between the serial bus and the microcontroller module 1 is disconnected. At this time, the serial bus is pulled up by the first resistor R1 to maintain a high level, thereby fully realizing the transmission drive of the serial bus. When the bus is idle, both the first switch Q1 and the second switch Q2 are in the off state. The circuit consumes only a small current through resistors such as the first resistor R1 and the seventh resistor R7, achieving low quiescent current operation. Thus, while ensuring signal transmission reliability and anti-interference capability, the circuit can maintain extremely low quiescent current when the bus is idle, meeting the design requirements of automotive-grade low power consumption. In some preferred embodiments, the switch control module 300 further includes a switch filter unit 120, which includes a third capacitor C3. One end of the third capacitor C3 is connected to the drive control unit 310, and the other end of the third capacitor C3 is grounded. The third capacitor C3 is the emitter filter capacitor for the second switching transistor Q2. It is used to absorb the current spikes and high-frequency noise generated during transistor switching, smooth emitter potential fluctuations, and improve the stability and anti-interference capability of the output signal. The first switching transistor Q1 and the second switching transistor Q2 can be NPN transistors of model MMSTA06HE3-TP. Furthermore, they can be further replaced with higher-specification NPN transistors according to automotive-grade temperature and voltage requirements to adapt to 24V systems or higher temperature applications.

[0047] Further, the base bias voltage regulator unit 320 includes: a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a second diode D2, and a first Zener diode ZD1; wherein, one end of the sixth resistor R6 is connected to the pass terminal of the drive control unit 310, and the other end of the sixth resistor R6 is connected to the power supply voltage; one end of the seventh resistor R7 is connected to the power supply voltage, and the other end of the seventh resistor R7 and the anode of the second diode D2 are connected to the control terminal of the drive control unit 310; the cathode of the second diode D2 is connected to the cathode of the first Zener diode ZD1, and the anode of the first Zener diode ZD1 is grounded; one end of the eighth resistor R8 is connected to the common terminal of the seventh resistor R7 and the drive control unit 310, and the other end of the eighth resistor R8 is connected to the common terminal of the cathode of the second diode D2 and the anode of the first Zener diode ZD1. The collector of the second switching transistor Q2 is connected in series with a sixth resistor R6, which is a collector load resistor. This resistor is used to limit the collector current when the second switching transistor Q2 is saturated and turned on, so as to avoid the bus overcurrent damaging the device. At the same time, it works with the bus-side circuit to optimize the signal edge slope and reduce electromagnetic interference emissions.

[0048] In this system, the first Zener diode ZD1 is connected to the base circuit of the second switching transistor Q2 via the second diode D2, and together with the seventh resistor R7 and the eighth resistor R8, forms a base bias and voltage regulation network. In this network, the seventh resistor R7 is connected to the power supply VS, providing a static bias path and initial potential reference for the base of the second switching transistor Q2. The eighth resistor R8 is used for current limiting and buffering, limiting the operating current of the Zener diode branch to prevent device overload. The first Zener diode ZD1 is a 12V Zener diode, used to clamp the voltage regulation base circuit during overvoltage, preventing high voltage backflow at the power supply VS from damaging the second switching transistor Q2 and surrounding circuits, thereby ensuring the stability of the base bias voltage under wide voltage conditions in automotive applications. Simultaneously, the second diode D2 is connected in parallel to the base circuit, acting as a clamping diode to absorb the spike voltage generated during switching, confining the base potential within a safe range, and further preventing damage to the emitter junction of the second switching transistor Q2 from transient overvoltage. In some preferred embodiments, the first Zener diode ZD1 can also be replaced with a TVS (Transient Voltage Suppressor) to improve the ESD protection level, or the EMI suppression effect of a specific frequency band can be optimized by adjusting the parameters of the first ferrite bead FB1, the first capacitor C1 and / or the second capacitor C2.

[0049] Based on the same inventive concept, a vehicle-mounted communication system is also provided, comprising the aforementioned serial communication bus transceiver circuit, at least one vehicle body control module, at least one sensing and detection module, and at least one execution module; the vehicle body control module, the sensing and detection module, and the execution module are respectively connected to the serial bus, and are used to output serial input signals to the serial bus and acquire serial output signals on the serial bus. The specific implementation is as described in the above embodiment of the serial communication bus transceiver circuit, and will not be repeated here.

[0050] This invention provides a serial communication bus transceiver circuit and an in-vehicle communication system, the advantages of which are: Employing a dual-transistor controlled switch architecture, combined with multi-stage EMI filtering, ESD protection, and level matching networks, this system enables the reception, transmission, and signal conditioning of signals on a serial bus, particularly a LIN bus, and the microcontroller module side. When the bus is idle, the circuit automatically enters a low-power state, significantly reducing quiescent current. During operation, it ensures signal integrity and interference immunity, making it suitable for automotive-grade LIN slave node applications.

[0051] Input and output are achieved through a signal interaction module. When serial input is achieved, the serial input signal is processed by the signal input module. When serial output is achieved, the signal is modulated by the switch control module. When the serial optimization signal is not detected, the signal interaction module and signal operation are terminated. This achieves signal input and output while reducing the static power consumption when the bus is idle, thus meeting the comprehensive requirements of low static current, low cost, and high reliability.

[0052] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A serial communication bus transceiver circuit, characterized in that, For connection to a microcontroller module, including: The signal input module is connected to the serial bus and is used to receive serial input signals and perform signal processing to obtain serial optimized signals. A signal interaction module, connected to the signal input module and the microcontroller module, is used to perform level conversion on the serial optimized signal and output a serial level signal to the microcontroller module; the microcontroller module is used to acquire and store the serial level signal in signal acquisition mode, and to output a transmission signal to the signal interaction module in signal output mode; the signal interaction module is used to output the transmission signal. A switch control module, connected to the signal interaction module and connected to a power supply, is used to collect the transmitted signal output by the signal interaction module, and output a serial output signal to the signal interaction module according to the transmitted signal and the power supply. The serial output signal is output to a serial bus through the signal interaction module. When the signal interaction module does not detect the serial optimization signal, the signal interaction module and the switch control module stop working.

2. The serial communication bus transceiver circuit according to claim 1, characterized in that, The signal input module includes a voltage divider unit and a filter unit. One end of the voltage divider unit is used to receive a serial input signal and to divide the serial input signal to obtain a serial voltage-divided signal. The filtering unit is connected to the voltage divider unit and is used to filter the serial voltage divider signal and output a serial optimized signal to the signal interaction module.

3. The serial communication bus transceiver circuit according to claim 2, characterized in that, The voltage divider unit includes: a first resistor, a first ferrite bead, and a second resistor; wherein... One end of the first resistor is connected to a pull-up power supply, the other end of the first resistor is connected to a serial bus and to one end of the first ferrite bead, the other end of the first ferrite bead is connected to one end of the second resistor, and the other end of the second resistor is connected to the signal interaction module.

4. The serial communication bus transceiver circuit according to claim 3, characterized in that, The filtering unit includes a first capacitor and a second capacitor. One end of the first capacitor is connected to the common terminal of the first resistor and the first ferrite bead, and the other end of the first capacitor is grounded. One end of the second capacitor is connected to the common terminal of the first ferrite bead and the second resistor, and the other end of the second capacitor is grounded.

5. The serial communication bus transceiver circuit according to claim 1, characterized in that, The signal interaction module includes: a third resistor, a first switching transistor, a first diode, and a fourth resistor; wherein, One end of the third resistor is connected to the signal input module, and the other end of the third resistor is connected to the base of the first switching transistor; the base of the first switching transistor is connected to the switch control module, and the emitter of the first switching transistor is connected to the common terminal of the third resistor and the signal input module; the collector of the first switching transistor is connected to the microcontroller module. The anode of the first switching transistor and one end of the fourth resistor are connected to the emitter of the first switching transistor, and the cathode of the first switching transistor and the other end of the fourth resistor are connected to the collector of the first switching transistor and the common terminal of the microcontroller module.

6. The serial communication bus transceiver circuit according to claim 1, characterized in that, The switching control module includes: a drive control unit and a base bias voltage regulator unit; wherein... The drive control unit is connected to the power supply and is connected to the base bias voltage regulator and the signal interaction module. It is used to collect the transmitted signal. The transmitted signal is used to control the drive control unit to turn on and off. The drive control unit outputs the on / off signal to the base bias voltage regulator. The base bias voltage regulator unit is connected to the power supply and is used to output the serial output signal to the drive control unit according to the on / off signal; the drive control unit is used to output the serial output signal to the signal interaction module.

7. The serial communication bus transceiver circuit according to claim 6, characterized in that, It also includes a switching filter unit, which includes a third capacitor. One end of the third capacitor is connected to the drive control unit, and the other end of the third capacitor is grounded.

8. The serial communication bus transceiver circuit according to claim 6, characterized in that, The drive control unit includes a fifth resistor and a second switching transistor. One end of the fifth resistor is connected to the signal interaction module and connected to a power supply. The other end of the fifth resistor is connected to the emitter of the second switching transistor. The base and emitter of the second switching transistor are connected to the base bias voltage regulator unit.

9. The serial communication bus transceiver circuit according to claim 6, characterized in that, The base bias voltage regulator unit includes: a sixth resistor, a seventh resistor, an eighth resistor, a second diode, and a first Zener diode; wherein, One end of the sixth resistor is connected to the path terminal of the drive control unit, and the other end of the sixth resistor is connected to the power supply voltage. One end of the seventh resistor is connected to the power supply voltage, and the other end of the seventh resistor and the anode of the second diode are connected to the control terminal of the drive control unit. The cathode of the second diode is connected to the cathode of the first Zener diode, and the anode of the first Zener diode is grounded. One end of the eighth resistor is connected to the common terminal of the seventh resistor and the drive control unit, and the other end of the eighth resistor is connected to the common terminal of the cathode of the second diode and the anode of the first Zener diode.

10. A vehicle-mounted communication system, characterized in that, It includes a serial communication bus transceiver circuit as described in any one of claims 1 to 9, at least one body control module, at least one sensing and detection module, and at least one execution module; the body control module, the sensing and detection module, and the execution module are respectively connected to the serial bus and are used to output serial input signals to the serial bus and acquire serial output signals on the serial bus.

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