A receiver of a can bus and a signal receiving device

Abstract

The application discloses a CAN bus receiver and relates to the communication field.The threshold setting module cooperates with a voltage reduction module to realize voltage reduction of the input signal of the CAN bus, so that an amplification module outputs corresponding level signals according to the input differential signals, the threshold setting module adjusts preset thresholds in the module based on the output signals of the amplification module, a hysteresis control structure is formed between the threshold setting module and the amplification module, the output signals are more stable, and the output signals are not easily affected by external environments or self devices, the anti-interference ability and stability of the whole receiver are improved, the inaccuracy problem caused by a cross hysteresis comparator and a load adjustment hysteresis comparator in a traditional mode is solved, the accuracy of the output result of the receiver is guaranteed, the reliability and safety of the receiver are improved, and the whole receiving process of the CAN bus is facilitated.The application further discloses a signal receiving device of the CAN bus, which has the same beneficial effects as the CAN bus receiver.

Description

Technical Field

[0001] This invention relates to the field of communications, and in particular to a receiver for a CAN bus. This invention also relates to a signal receiving device for a CAN bus. Background Technology

[0002] With the continuous development of CAN (Controller Area Network) bus, the application requirements for it are also becoming more and more demanding. Typically, the interface voltage of the CAN communication chip used as a CAN controller is relatively high, and in worst cases, the input voltage can even reach the range of -70V to 70V. At the same time, with the increase in the processing speed of the Internet of Things, the speed requirement for CAN has reached 5Mbps. The high external voltage and speed requirements place high demands on the voltage withstand capability, speed, and accuracy of the CAN receiver.

[0003] Current CAN receivers typically employ a combination of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and a comparator. The receiver's input amplification is achieved using the MOSFET. To meet higher speed requirements, high-voltage MOSFETs cannot be used. However, this necessitates a higher step-down ratio in the buck converter to prevent device breakdown. A higher step-down ratio results in a smaller signal that the receiver needs to process, down to a few mV. Such small signals are susceptible to environmental interference, and a transmission speed of 1 Mbps is insufficient to meet accuracy requirements. Furthermore, the CAN protocol requires the receiver to stably monitor signals, such as outputting "0" for input signals >0.9V and "1" for input signals <0.5V. This necessitates a stable hysteresis in the receiver, which current technologies primarily achieve using interlocked comparators or feedback-controlled comparators. Existing CAN receivers suffer from poor overall anti-interference capabilities and hysteresis stability due to the inherent characteristics of MOSFETs and comparators. They are also susceptible to the influence of the manufacturing process of the components in the chip, which is detrimental to the application of CAN receivers. Summary of the Invention

[0004] The purpose of this invention is to provide a CAN bus receiver and signal receiving device. The threshold setting module and the amplification module form a hysteresis control structure, which makes the output signal of the amplification module more stable and less susceptible to the influence of the external environment or its own components. This improves the anti-interference capability and stability of the entire receiver, solves the inaccuracy problem caused by cross hysteresis comparators and load adjustment hysteresis comparators in traditional methods, ensures the accuracy of the receiver's output results, improves the reliability and security of the receiver, and facilitates the entire CAN bus receiving process.

[0005] To solve the above-mentioned technical problems, the present invention provides a CAN bus receiver, comprising:

[0006] The step-down module has a first input terminal connected to the high level of the CAN bus, a second input terminal connected to the low level of the CAN bus, a first output terminal connected to the first input terminal of the amplifier module, and a second output terminal connected to the second input terminal of the amplifier module.

[0007] The threshold setting module has its input end connected to the output end of the amplification module, and its output end connected to the third input end of the buck module and the third input end of the amplification module, respectively. It is used to cooperate with the buck module to step down the high level of the CAN bus to a first signal output based on a preset threshold, step down the low level of the CAN bus to a second signal output based on the preset threshold, and adjust the preset threshold according to the output signal of the amplification module.

[0008] The amplification module, whose output terminal serves as the output terminal of the receiver, is used to output a first level when the difference between the first signal and the second signal meets a preset condition; and to output a second level when the difference between the first signal and the second signal does not meet the preset condition, wherein the first level is opposite to the second level.

[0009] Preferably, the step-down module includes a filter capacitor, a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, and a fourth voltage divider resistor;

[0010] The first terminal of the first voltage divider resistor is connected to the low level of the CAN bus, and the second terminal is connected to the first terminal of the filter capacitor and the first terminal of the second voltage divider resistor. The second terminal of the second voltage divider resistor is connected to the common-mode voltage and the first terminal of the third voltage divider resistor. The second terminal of the third voltage divider resistor is connected to the first terminal of the fourth voltage divider resistor and the second terminal of the filter capacitor. The second terminal of the fourth voltage divider resistor is connected to the high level of the CAN bus. The second terminal of the first voltage divider resistor serves as the first output terminal of the buck module, and the second terminal of the third voltage divider resistor serves as the second output terminal of the buck module.

[0011] Preferably, the threshold setting module includes a reset module, a threshold adjustment module, and an output module;

[0012] The input terminal of the threshold adjustment module is connected to the output terminal of the amplification module, and the output terminal is connected to the input terminal of the output module. The first terminal of the reset module is connected to the reset signal, and the second terminal is connected to the input terminal of the output module. The output terminal of the output module serves as the output terminal of the threshold setting module.

[0013] The threshold adjustment module is used to adjust the preset threshold according to the output signal of the amplification module, and transmit the signal corresponding to the preset threshold to the output module;

[0014] The output module is used in conjunction with the step-down module to step down the high level of the CAN bus to a first signal output based on a preset threshold, and to step down the low level of the CAN bus to a second signal output based on the preset threshold.

[0015] Preferably, the reset module includes a first reset switch, a second reset switch, a reset resistor, and an inverter;

[0016] The first terminal of the first reset switch is connected to the power supply, and the second terminal is connected to the first terminal of the second reset switch. The second terminal of the second reset switch is connected to the input terminal of the inverter and the first terminal of the reset resistor. The output terminal of the inverter is connected to the reset signal. The second terminal of the reset resistor is grounded. The control terminals of the first reset switch and the second reset switch are connected to the input terminal of the output module.

[0017] Preferably, the threshold adjustment module includes a first threshold switch, a second threshold switch, a first threshold resistor, a second threshold resistor, a current source switch, and a first current limiting resistor;

[0018] The control terminal of the first threshold switch is connected to the output terminal of the amplification module. The first terminal is grounded. The second terminal is connected to the first terminal of the first threshold resistor and the first terminal of the second threshold resistor. The second terminal of the first threshold resistor is grounded. The second terminal of the second threshold resistor is connected to the first terminal of the second threshold switch and the control terminal of the current source switch. The first terminal of the current source switch is connected to the control terminal of the current source and the second threshold switch. The second terminal is connected to the first terminal of the first current limiting resistor. The second terminal of the first current limiting resistor is grounded. The second terminal of the second threshold switch is connected to the input terminal of the output module.

[0019] Preferably, the output module includes a second current-limiting resistor, a third current-limiting resistor, a first output switch, a second output switch, a third output switch, a fourth output switch, a fifth output switch, a sixth output switch, a seventh output switch, and an eighth output switch;

[0020] The first terminal of the first output switch is connected to the power supply, and the second terminal is connected to the first terminal of the second output switch. The first terminal of the third output switch is connected to the power supply, and the second terminal is connected to the first terminal of the fourth output switch. The control terminals of the first and third output switches are connected to the control terminals of the first and second reset switches. The control terminals of the second and fourth output switches are connected to the control terminals of the second reset switch. The first terminal of the second current-limiting resistor is connected to the output terminal of the threshold setting module and the control terminal of the second reset switch, respectively. The second terminal is connected to the second terminal of the second output switch and the control terminal of the first reset switch, respectively. The second terminal of the fourth output switch is connected to the first terminal of the third current-limiting resistor, respectively. The control terminals of the fifth and seventh output switches are connected to the control terminals of the fifth, sixth, and eighth output switches, respectively. The second terminal of the fifth output switch is connected to the first terminal of the sixth output switch, and the second terminal of the sixth output switch is grounded. The first terminal of the seventh output switch serves as the output terminal of the output module, and the second terminal is connected to the first terminal of the eighth output switch, and the second terminal of the eighth output switch is grounded.

[0021] Preferably, the amplification module includes a pre-amplification module, a first level shifting module, a main amplification module, an output amplification module, and a bias current module;

[0022] The first input terminal of the pre-amplification module is connected to the first output terminal of the buck module, the second input terminal is connected to the second output terminal of the buck module, the first output terminal is connected to the first input terminal of the first level shift module, the second output terminal is connected to the second input terminal of the first level shift module, the first output terminal of the first level shift module is connected to the first input terminal of the main amplification module, the second output terminal of the first level shift module is connected to the second input terminal of the main amplification module, the first output terminal of the main amplification module is connected to the first input terminal of the output amplification module, the second output terminal of the main amplification module is connected to the second input terminal of the output amplification module, the output terminal of the output amplification module serves as the output terminal of the amplification module, and the third input terminal of the pre-amplification module, the third input terminal of the first level shift module, the third input terminal of the main amplification module, and the third input terminal of the output amplification module are respectively connected to the bias current module.

[0023] The bias current module is used to provide the fixed bias current required for normal operation of the pre-amplification module, the first level shifting module, the main amplification module and the output amplification module;

[0024] The output amplification module is used to output a high level when the difference between the first signal and the second signal meets a preset condition, and to output a low level when the difference between the first signal and the second signal does not meet the preset condition. The high level is the first level and the low level is the second level.

[0025] Preferably, the amplification module further includes a second level shifting module;

[0026] The first input terminal of the second level shifting module is connected to the first output terminal of the main amplification module, the second input terminal is connected to the second output terminal of the main amplification module, the first output terminal is connected to the first input terminal of the output amplification module, the second output terminal is connected to the second input terminal of the output amplification module, and the third input terminal is connected to the bias current module.

[0027] Preferably, the pre-amplification module includes a first amplification switch, a second amplification switch, a first protection resistor, a second protection resistor, a first diode, a second diode, a third protection resistor, and a fourth protection resistor;

[0028] The control terminal of the first amplifying switch is connected to the first output terminal of the step-down module and the first terminal of the first protective resistor. The second terminal of the first protective resistor is connected to the first terminal of the first amplifying switch, the first terminal of the second amplifying switch, the first terminal of the second protective resistor, and the bias current module. The control terminal of the second amplifying switch is connected to the second output terminal of the step-down module and the second terminal of the second protective resistor. The second terminal of the first amplifying switch is connected to the negative terminal of the first diode. The second terminal of the second amplifying switch is connected to the negative terminal of the second diode. The positive terminal of the first diode is connected to the first terminal of the third protective resistor and the first input terminal of the first level shifting module. The positive terminal of the second diode is connected to the first terminal of the fourth protective resistor and the second input terminal of the first level shifting module. The second terminals of the third and fourth protective resistors are connected to the power supply.

[0029] To solve the above-mentioned technical problems, the present invention also provides a CAN bus signal receiving device, including a CAN controller and a CAN bus receiver as described above;

[0030] The CAN controller is connected to the receiver of the CAN bus, and the receiver of the CAN bus is connected to the CAN bus.

[0031] This invention provides a CAN bus receiver, including a step-down module, a threshold setting module, and an amplification module. The threshold setting module works with the step-down module to step down the input signal of the CAN bus, so that the amplification module can output a corresponding level signal based on the differential signal input to the CAN bus. Simultaneously, the threshold setting module adjusts its internal preset threshold based on the output signal of the amplification module, further ensuring the step-down process of the CAN bus input signal. The threshold setting module and the amplification module form a hysteresis control structure, making the output signal of the amplification module more stable and less susceptible to influences from the external environment or its own components. This improves the overall anti-interference capability and stability of the receiver, solves the inaccuracy problems caused by cross-hysteresis comparators and load-adjusting hysteresis comparators in traditional methods, ensures the accuracy of the receiver's output results, improves the reliability and security of the receiver, and facilitates the entire CAN bus reception process.

[0032] The present invention also provides a CAN bus signal receiving device, which has the same beneficial effects as the CAN bus receiver described above. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments 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 these drawings without creative effort.

[0034] Figure 1 A schematic diagram of the structure of a CAN bus receiver provided by the present invention;

[0035] Figure 2 A schematic diagram of another CAN bus receiver provided by the present invention;

[0036] Figure 3 A schematic diagram of the threshold setting module and step-down module of a CAN bus receiver provided by the present invention;

[0037] Figure 4 A schematic diagram of the structure of an amplifier module for a CAN bus receiver provided by the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of a CAN bus signal receiving device provided by the present invention. Detailed Implementation

[0039] The core of this invention is to provide a CAN bus receiver and signal receiving device. The threshold setting module and the amplification module form a hysteresis control structure, which makes the output signal of the amplification module more stable and less susceptible to the influence of the external environment or its own components. This improves the anti-interference capability and stability of the entire receiver, solves the inaccuracy problem caused by cross hysteresis comparators and load adjustment hysteresis comparators in traditional methods, ensures the accuracy of the receiver's output results, improves the reliability and security of the receiver, and facilitates the entire CAN bus receiving process.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The CAN bus receiver provided in this application is mainly used in the field of CAN high-voltage interface communication. It adopts integrated circuit technology and relates to a signal receiver. The CAN bus receiver is a necessary unit for the CAN controller to directly interact with the CAN bus. Detailed implementation is described below.

[0042] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a CAN bus receiver provided by the present invention;

[0043] Please refer to Figure 2 , Figure 2 A schematic diagram of another CAN bus receiver provided by the present invention; Figure 2 In this context, CANH refers to the high level of the CAN bus input; CANL refers to the low level of the CAN bus input; INH refers to the first signal after step-down; INL refers to the second signal after step-down; and RXD refers to the receiver's output signal.

[0044] To solve the above-mentioned technical problems, the present invention provides a CAN bus receiver, comprising:

[0045] The step-down module 1 has its first input terminal connected to the high level of the CAN bus, its second input terminal connected to the low level of the CAN bus, its first output terminal connected to the first input terminal of the amplifier module 3, and its second output terminal connected to the second input terminal of the amplifier module 3.

[0046] The threshold setting module 2 has its input end connected to the output end of the amplification module 3, and its output end connected to the third input end of the step-down module 1 and the third input end of the amplification module 3, respectively. It is used to cooperate with the step-down module 1 to step down the high level of the CAN bus to the first signal output based on the preset threshold, and to step down the low level of the CAN bus to the second signal output based on the preset threshold, and to adjust the preset threshold according to the output signal of the amplification module 3.

[0047] Amplification module 3, whose output terminal serves as the output terminal of the receiver, is used to output a first level when the difference between the first signal and the second signal meets a preset condition; and to output a second level when the difference between the first signal and the second signal does not meet the preset condition. The first level and the second level are opposite.

[0048] Specifically, step-down module 1 is connected to the CAN bus, receiving the high and low levels of the CAN bus. Step-down module 1 and threshold setting module 2 work together to step down the signal received from the CAN bus, and transmit the stepped-down first and second signals to amplification module 3. Amplification module 3 converts the differential signal composed of the first and second signals into a logic level signal and outputs it, thereby realizing the function of the CAN bus receiver to convert the differential level transmitted from the CAN bus into a logic level. Threshold setting module 2 and amplification module 3 form a hysteresis control structure similar to positive feedback. Threshold setting module 2 receives the output signal of amplification module 3 and adjusts its internal circuit according to different level signals output by amplification module 3 to adjust the preset threshold. Different preset thresholds correspond to different offset signals, which, together with step-down module 1, realize different degrees of step-down of the signal on the CAN bus.

[0049] Taking a high-level signal as the first level and a low-level signal as the second level, as a specific embodiment, when the signal output by the amplification module 3 is a high-level signal, the threshold setting module 2 controls the internal circuit to output a larger current value, which, in conjunction with the buck module 1, achieves a first signal and a second signal with relatively small output offsets, thereby stabilizing the high-level signal output by the amplification module 3. Similarly, when the signal output by the amplification module 3 is a low-level signal, the threshold setting module 2 controls the internal circuit to output a smaller current value, which, in conjunction with the buck module 1, achieves a first signal and a second signal with relatively large output offsets, thereby stabilizing the low-level signal output by the amplification module 3. There are many specific ways to achieve voltage reduction through the cooperation between the threshold setting module 2 and the buck module 1, and this application does not impose any particular limitation here.

[0050] It is understood that the preset threshold is determined based on the specific circuit structure of the threshold setting module 2 itself. The preset threshold can be adjusted by adjusting the circuit structure of the threshold setting module 2 or the relevant parameters of the specific components in the circuit to obtain a better target value. Since the output signal of the amplification module 3 is usually at the first level or the second level, the corresponding preset threshold is usually also two thresholds. This application does not make any special restrictions on the specific setting and implementation of the preset threshold. There are multiple ways to achieve this. It can be achieved by whether or not a fixed resistor is connected, or by other methods. The threshold setting module 2 can adjust the preset threshold by adjusting the output current to achieve different voltage reduction processes in conjunction with the step-down module 1, or by other methods. This application does not make any special restrictions on this.

[0051] It should be noted that the difference between the first and second signals meeting the preset conditions includes the difference between the first and second signals reaching a preset difference value, while the difference between the first and second signals not meeting the preset conditions includes the difference between the first and second signals not reaching the preset difference value or the receiver not receiving the differential signal from the CAN bus. The preset difference value is determined based on the value of the differential signal formed by subtracting the low level from the high level of the received CAN bus. In practical applications, when the received differential signal of the CAN bus is greater than the preset value, the receiver needs to convert it to the first level; when the received differential signal of the CAN bus is less than the preset value, the receiver needs to convert it to the second level. The first and second levels are opposite to each other to monitor the CAN bus signal, and the level signal will then be transmitted to the CAN controller so that the CAN controller can convert it into the corresponding control signal and transmit it to the processor or other remote devices for processing. This application does not impose any special limitations on the setting method and specific value of the preset conditions and preset difference value, which can be adjusted according to actual application requirements.

[0052] Specifically, the circuit structure and implementation of the step-down module 1, the threshold setting module 2, and the amplification module 3 can be implemented in various forms, and this application does not impose any particular limitation on them. The step-down module 1 can be implemented by a voltage divider circuit or other forms of step-down circuit, the threshold setting module 2 can be implemented by combining multiple MOS (Metal-Oxide-Semiconductor) transistors and resistors, and the amplification module 3 can be implemented by a three-stage amplification structure or other forms of circuit.

[0053] The buck module 1 outputs a signal to the amplification module 3. Simultaneously, the buck module 1, in conjunction with the threshold setting module 2, performs the voltage reduction process. Upon receiving the signal, the amplification module 3 determines that a bus signal has been detected, and the detected status is fed back to the threshold setting module 2 for precise hysteresis control, thus filtering out some jitter noise in the bus signal. The threshold module also outputs a reset signal as a stability indicator to mute the amplification module 3, even when it is not operating. This hysteresis control structure effectively filters out interference from the CAN bus during operation.

[0054] This invention provides a CAN bus receiver, including a step-down module 1, a threshold setting module 2, and an amplification module 3. The threshold setting module 2 works in conjunction with the step-down module 1 to step down the input signal of the CAN bus, so that the amplification module 3 can output a corresponding level signal based on the differential signal input to the CAN bus. Simultaneously, the threshold setting module 2 adjusts its internal preset threshold based on the output signal of the amplification module 3, further ensuring the step-down process of the CAN bus input signal. The threshold setting module 2 and the amplification module 3 form a hysteresis control structure, making the output signal of the amplification module 3 more stable and less susceptible to influence from external environment or its own components. This improves the anti-interference capability and stability of the entire receiver, solves the inaccuracy problems caused by cross-hysteresis comparators and load-adjusting hysteresis comparators in traditional methods, ensures the accuracy of the receiver's output results, improves the reliability and security of the receiver, and facilitates the entire CAN bus reception process.

[0055] Based on the above embodiments,

[0056] Please refer to Figure 3 , Figure 3 A schematic diagram of the threshold setting module and step-down module of a CAN bus receiver provided by the present invention;

[0057] Please refer to Figure 4 , Figure 4 A schematic diagram of the structure of an amplifier module for a CAN bus receiver provided by the present invention;

[0058] In one preferred embodiment, the step-down module 1 includes a filter capacitor C0, a first voltage divider resistor R9, a second voltage divider resistor R10, a third voltage divider resistor R11, and a fourth voltage divider resistor R12.

[0059] The first terminal of the first voltage divider resistor R9 is connected to the low level of the CAN bus, and the second terminal is connected to the first terminal of the filter capacitor C0 and the first terminal of the second voltage divider resistor R10. The second terminal of the second voltage divider resistor R10 is connected to the common-mode voltage and the first terminal of the third voltage divider resistor R11. The second terminal of the third voltage divider resistor R11 is connected to the first terminal of the fourth voltage divider resistor R12 and the second terminal of the filter capacitor C0. The second terminal of the fourth voltage divider resistor R12 is connected to the high level of the CAN bus. The second terminal of the first voltage divider resistor R9 serves as the first output terminal of the buck module 1, and the second terminal of the third voltage divider resistor R11 serves as the second output terminal of the buck module 1.

[0060] Specifically, a voltage divider circuit consisting of the first voltage divider resistor R9, the second voltage divider resistor R10, the third voltage divider resistor R11, and the fourth voltage divider resistor R12 is used to reduce the high and low levels of the CAN bus. A filter capacitor C0 is added to the circuit to reduce signal interference that may occur during the voltage reduction process. The process is based on the common-mode voltage. This application does not impose specific limitations on the specific settings and implementation methods of the common-mode voltage. Figure 3 The application does not impose any special limitations on the type and specific implementation of the first voltage divider resistor R9, the second voltage divider resistor R10, the third voltage divider resistor R11, and the fourth voltage divider resistor R12 as shown in the Vcm diagram.

[0061] The step-down module 1 functions as a voltage divider circuit consisting of filter capacitor C0, first voltage divider resistor R9, second voltage divider resistor R10, third voltage divider resistor R11, and fourth voltage divider resistor R12. The entire circuit structure is simple, the components used are easy to implement, and the cost is low. Adding filter capacitor C0 further ensures the anti-interference capability and stability of the step-down module 1, effectively realizing the voltage reduction function so that the subsequent amplification module 3 can work normally, ensuring the accuracy of the receiver's output results, improving the reliability and security of the receiver, and facilitating the entire CAN bus reception process.

[0062] In a preferred embodiment, the threshold setting module 2 includes a reset module, a threshold adjustment module, and an output module;

[0063] The input terminal of the threshold adjustment module is connected to the output terminal of the amplification module 3, and the output terminal is connected to the input terminal of the output module. The first terminal of the reset module is connected to the reset signal, and the second terminal is connected to the input terminal of the output module. The output terminal of the output module serves as the output terminal of the threshold setting module 2.

[0064] The threshold adjustment module is used to adjust the preset threshold according to the output signal of the amplification module 3, and transmit the signal corresponding to the preset threshold to the output module;

[0065] The output module is used in conjunction with the step-down module 1 to step down the high level of the CAN bus to a first signal output based on a preset threshold, and to step down the low level of the CAN bus to a second signal output based on a preset threshold.

[0066] Specifically, a threshold adjustment module is used to implement the adjustment process of the threshold setting module 2 based on the output signal of the amplification module 3 for the preset threshold. An output module is used to implement the voltage reduction process between the threshold setting module 2 and the step-down module 1. A reset module is used to implement the reset control of the amplification module 3. When the internal working current of the receiver is still unstable, the threshold setting module 2 will output a reset signal to the amplification module 3 through the reset module to avoid erroneous output operation caused by the unstable working current of the amplification module 3, thus ensuring the normal operation of the amplification module 3.

[0067] It is understood that this application does not impose any particular limitations on the specific implementation method of how the threshold adjustment module adjusts the threshold; it can be achieved by adjusting the current. The threshold adjustment module transmits the adjusted target threshold to the step-down module 1 through the output module, and works with the step-down module 1 to achieve different degrees of voltage reduction of the CAN bus signal, thereby forming a hysteresis control structure similar to positive feedback. This application does not impose any particular limitations on the specific setting method and implementation method of the reset signal; multiple implementation methods exist. Specifically, this application does not impose any particular limitations on the circuit structure and specific implementation method of the threshold adjustment module, output module, and reset module; they can be adjusted according to actual application requirements and application environment.

[0068] A threshold adjustment module is used to implement the threshold setting module 2's adjustment process based on the output signal of the amplification module 3 for the preset threshold. An output module is used to implement the voltage reduction process between the threshold setting module 2 and the step-down module 1. A reset module is used to implement the reset control of the amplification module 3. Through these three modules, the function of the threshold setting module 2 is realized, making the circuit structure of the threshold setting module 2 clearer and more explicit, so as to ensure the normal operation of the subsequent amplification module 3, guarantee the accuracy of the receiver's output results, improve the receiver's reliability and security, and facilitate the entire CAN bus receiving process.

[0069] In a preferred embodiment, the reset module includes a first reset switch PM5, a second reset switch PM6, a reset resistor R6, and an inverter INV1;

[0070] The first terminal of the first reset switch PM5 is connected to the power supply, and the second terminal is connected to the first terminal of the second reset switch PM6. The second terminal of the second reset switch PM6 is connected to the input terminal of the inverter INV1 and the first terminal of the reset resistor R6, respectively. The output terminal of the inverter INV1 is connected to the reset signal, and the second terminal of the reset resistor R6 is grounded. The control terminals of the first reset switch PM5 and the second reset switch PM6 are connected to the input terminals of the output module, respectively.

[0071] Specifically, the reset module can be implemented using the first reset switch PM5, the second reset switch PM6, the reset resistor R6, and the inverter INV1. When there are abnormal conditions such as unstable current in the receiver, the threshold setting module 2 outputs a reset signal to control the amplification module 3 to reset. The addition of the inverter INV1 in the circuit can enhance the stability of the reset signal. The control terminals of the two reset switches are connected to the other two modules of the threshold setting module 2, and can be turned on or off according to the circuit conditions in the threshold setting module 2 to realize the output of the reset signal. The reset resistor R6 mainly serves to limit current and protect the circuit.

[0072] It is understood that this application does not impose any special limitations on the type and specific implementation of the first reset switch PM5, the second reset switch PM6, the reset resistor R6, and the inverter INV1. The first reset switch PM5 and the second reset switch PM6 can adopt a P-type MOSFET or similar switch structure. This embodiment describes a specific implementation of the reset module. It is understood that the entire reset module can be modified into a pull-down structure, and the first reset switch PM5 and the second reset switch PM6 can also be implemented using N-type MOSFETs. This application does not impose any special limitations on the circuit structure and specific implementation of the reset module.

[0073] The reset module is implemented using a first reset switch PM5, a second reset switch PM6, a reset resistor R6, and an inverter INV1. Adding the inverter INV1 makes the reset signal more stable, effectively achieving the function of outputting a reset signal while also improving the anti-interference capability of the reset signal. This further enhances the anti-interference capability of the threshold setting module 2, ensuring the normal operation of the subsequent amplification module 3. The entire circuit structure is simple, the components used are easy to implement, and the cost is low. It ensures the accuracy of the receiver's output, improves the receiver's reliability and security, and facilitates the entire CAN bus reception process.

[0074] In a preferred embodiment, the threshold adjustment module includes a first threshold switch NM1, a second threshold switch NM2, a first threshold resistor R2, a second threshold resistor R3, a current source switch N1, and a first current limiting resistor R1.

[0075] The control terminal of the first threshold switch NM1 is connected to the output terminal of the amplifier module 3. The first terminal is grounded. The second terminal is connected to the first terminal of the first threshold resistor R2 and the first terminal of the second threshold resistor R3. The second terminal of the first threshold resistor R2 is grounded. The second terminal of the second threshold resistor R3 is connected to the first terminal of the second threshold switch NM2 and the control terminal of the current source switch N1. The first terminal of the current source switch N1 is connected to the control terminal of the current source I1 and the second threshold switch NM2. The second terminal is connected to the first terminal of the first current limiting resistor R1. The second terminal of the first current limiting resistor R1 is grounded. The second terminal of the second threshold switch NM2 is connected to the input terminal of the output module.

[0076] It is understandable that a threshold adjustment module can be implemented using a first threshold switch NM1, a second threshold switch NM2, a first threshold resistor R2, a second threshold resistor R3, a current source switch N1, and a first current-limiting resistor R1. The first threshold switch NM1 is turned on or off based on the output signal received from the amplification module 3. When the first threshold switch NM1 is on, the first threshold resistor R2 is short-circuited by the first threshold switch NM1 and is not connected to the circuit of the threshold adjustment module, resulting in a larger output current of the threshold adjustment module. When the first threshold switch NM1 is off, the circuit containing the first threshold switch NM1 is broken, and the first threshold resistor R2 is connected to the circuit of the threshold adjustment module, resulting in a smaller output current of the threshold adjustment module. The second threshold resistor R3 and the first current-limiting resistor R1 mainly serve as voltage dividers and current limiters to further protect the circuit. The first threshold switch NM1 also affects the current magnitude at the control terminal of the current source switch N1, thereby affecting the control process of the current source I1 on the control terminal of the second threshold switch NM2. The first threshold switch NM1 and the second threshold switch NM2 together constitute a structure similar to a current source.

[0077] Specifically, this application does not impose any particular limitations on the types and specific implementation methods of the first threshold switch NM1, the second threshold switch NM2, the first threshold resistor R2, the second threshold resistor R3, the current source switch N1, and the first current limiting resistor R1. The first threshold switch NM1 and the second threshold switch NM2 can be N-type MOSFETs, and the current source switch N1 can be an NPN transistor. This embodiment describes a specific implementation method of the threshold adjustment module. It is understood that the threshold adjustment module can be modified into a pull-up structure, and the first threshold switch NM1 and the second threshold switch NM2 can also be implemented using P-type MOSFETs. This application does not impose any particular limitations on the circuit structure and specific implementation method of the threshold adjustment module.

[0078] The threshold adjustment module is implemented using a first threshold switch NM1, a second threshold switch NM2, a first threshold resistor R2, a second threshold resistor R3, a current source switch N1, a first current-limiting resistor R1, and a current source I1. The output current of the threshold setting module 2 is adjusted by controlling whether the first threshold resistor R2 is connected to the circuit, thereby completing the different degrees of voltage reduction process in conjunction with the subsequent step-down module 1. This effectively realizes the function of the threshold adjustment module. The entire circuit structure is simple, the components used are easy to implement, and the cost is low, which ensures the stable output of the subsequent amplification module 3, guarantees the accuracy of the receiver's output results, improves the reliability and security of the receiver, and is beneficial to the entire reception process of the CAN bus.

[0079] In a preferred embodiment, the output module includes a second current-limiting resistor R4, a third current-limiting resistor R5, a first output switch PM1, a second output switch PM2, a third output switch PM3, a fourth output switch PM4, a fifth output switch NM4, a sixth output switch NM3, a seventh output switch NM6, and an eighth output switch NM5.

[0080] The first terminal of the first output switch PM1 is connected to the power supply, and the second terminal is connected to the first terminal of the second output switch PM2. The first terminal of the third output switch PM3 is connected to the power supply, and the second terminal is connected to the first terminal of the fourth output switch PM4. The control terminals of the first output switch PM1, the third output switch PM3, and the first reset switch PM5 are connected. The control terminals of the second output switch PM2, the fourth output switch PM4, and the second reset switch PM6 are connected. The first terminal of the second current-limiting resistor R4 is connected to the output terminal of the threshold setting module 2 and the control terminal of the second reset switch PM6, respectively. The second terminal is connected to the second terminal of the second output switch PM2 and the first reset switch PM6, respectively. The control terminal of the position switch PM5 is connected. The second terminal of the fourth output switch PM4 is connected to the first terminal of the third current-limiting resistor R5, the control terminal of the fifth output switch NM4, and the control terminal of the seventh output switch NM6. The second terminal of the third current-limiting resistor R5 is connected to the first terminal of the fifth output switch NM4, the control terminal of the sixth output switch NM3, and the control terminal of the eighth output switch NM5. The second terminal of the fifth output switch NM4 is connected to the first terminal of the sixth output switch NM3. The second terminal of the sixth output switch NM3 is grounded. The first terminal of the seventh output switch NM6 serves as the output terminal of the output module, and the second terminal is connected to the first terminal of the eighth output switch NM5. The second terminal of the eighth output switch NM5 is grounded.

[0081] Specifically, the output module is implemented through the second current-limiting resistor R4, the third current-limiting resistor R5, the first output switch PM1, the second output switch PM2, the third output switch PM3, the fourth output switch PM4, the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5. The first output switch PM1, the second output switch PM2, the third output switch PM3, and the fourth output switch PM4 together form the structure of a current mirror; the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5 together form the structure of a current mirror; the second current-limiting resistor R4 and the third current-limiting resistor R5 mainly serve the function of voltage division and current limiting, further protecting the circuit;

[0082] It is understood that this application does not impose any special limitations on the types and specific implementation methods of the second current-limiting resistor R4, the third current-limiting resistor R5, the first output switch PM1, the second output switch PM2, the third output switch PM3, the fourth output switch PM4, the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5; the first output switch PM1, the second output switch PM2, the third output switch PM3, and the fourth output switch PM4 can be P-type MOSFETs, and the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5 can be P-type MOSFETs. M5 can be an N-type MOSFET. In this embodiment, the current mirrors formed by the first output switch PM1, the second output switch PM2, the third output switch PM3, and the fourth output switch PM4, as well as the current mirrors formed by the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5, are two pairs of current mirrors. Alternatively, they can be implemented with a single pair of current mirrors. The internal circuit structure and specific implementation method of the output module can be adjusted according to the structure of the threshold adjustment module and the reset module. This application does not impose any special limitations here. The internal current mirror structure can also be implemented using a non-cascode single-transistor structure.

[0083] The output module is implemented using the second current-limiting resistor R4, the third current-limiting resistor R5, the first output switch PM1, the second output switch PM2, the third output switch PM3, the fourth output switch PM4, the fifth output switch NM4, the sixth output switch NM3, the seventh output switch NM6, and the eighth output switch NM5. A current mirror structure enables precise current replication, avoiding the influence of process and temperature on the circuit. The current signal corresponding to the preset threshold output by the threshold adjustment module is accurately output to the buck module 1, which is beneficial for the accurate execution of the subsequent bucking process. The entire circuit structure is simple, the components used are easy to implement, and the cost is low, ensuring accurate output from the subsequent amplification module 3. This guarantees the accuracy of the receiver's output results, improves the receiver's reliability and security, and facilitates the entire CAN bus reception process.

[0084] In one preferred embodiment, the amplification module 3 includes a pre-amplification module, a first level shifting module, a main amplification module, an output amplification module, and a bias current module;

[0085] The first input terminal of the pre-amplification module is connected to the first output terminal of the buck module 1, the second input terminal is connected to the second output terminal of the buck module 1, the first output terminal is connected to the first input terminal of the first level shift module, the second output terminal is connected to the second input terminal of the first level shift module, the first output terminal of the first level shift module is connected to the first input terminal of the main amplification module, the second output terminal of the first level shift module is connected to the second input terminal of the main amplification module, the first output terminal of the main amplification module is connected to the first input terminal of the output amplification module, the second output terminal of the main amplification module is connected to the second input terminal of the output amplification module, the output terminal of the output amplification module serves as the output terminal of the amplification module 3, and the third input terminal of the pre-amplification module, the third input terminal of the first level shift module, the third input terminal of the main amplification module, and the third input terminal of the output amplification module are respectively connected to the bias current module.

[0086] The bias current module is used to provide the fixed bias current required for normal operation of the pre-amplification module, the first level shift module, the main amplification module, and the output amplification module;

[0087] The output amplification module outputs a high level when the difference between the first signal and the second signal meets a preset condition, and outputs a low level when the difference between the first signal and the second signal does not meet the preset condition. The high level is the first level, and the low level is the second level.

[0088] Considering the problems of large transmission delay and difficulty in balancing voltage withstand capability and high precision in existing receivers, the amplification module 3 is implemented through a three-stage amplification structure consisting of a pre-amplification module, a first level shift module, a main amplification module, an output amplification module, and a bias current module. The pre-amplification module performs initial amplification, and then the signal is transmitted to the main amplification module through the first level shift module. The first level shift module also adjusts the bias point. The main amplification module performs secondary amplification, and then the amplified signal is converted into a logic level signal through the output amplification module. Considering the normal operation of the pre-amplification module, the first level shift module, the main amplification module, and the output amplification module, a bias current module is set to provide them with a fixed bias current required for normal operation. This structure has a relatively large amplification factor, which is beneficial for completing the process of converting differential signals into logic levels, and the accuracy of the output signal is also relatively high.

[0089] Specifically, this application does not impose any particular limitations on the circuit structure and implementation of the pre-amplification module, the first level shifting module, the main amplification module, the output amplification module, and the bias current module. The pre-amplification module, the main amplification module, and the output amplification module can adopt an NPN structure circuit, which is more conducive to reducing the transmission delay of the entire circuit and ensuring high accuracy while reducing the withstand voltage.

[0090] by Figure 4 For example; INH and INL are the first and second signals received by amplification module 3; the pre-amplification module is implemented through the first amplification switch N2, the second amplification switch N3, the first protection resistor R13, the second protection resistor R14, the first diode D1, the second diode D2, the third protection resistor R15, and the fourth protection resistor R16; the first level shifting module is implemented through switching transistors N4 and N5; the main amplification module is implemented through switching transistors N6 and N7, resistors R17 and R18, with resistors R17 and R18 mainly serving as voltage dividers and current limiters; through switching transistors... The output amplification module is implemented using transistors NM15, NM16, NM17, NM18, PM7, PM8, PM9, and PM10, inverter IN2, and OR gate OR1. RST refers to the reset signal output by threshold setting module 2, and RXD refers to the signal output by amplification module 3. The bias current module is implemented using current source I2, transistors NM7, NM8, NM9, NM10, NM11, NM12, NM13, and NM14. This is understandable. Figure 4 The diagram shown is only one specific implementation of the amplification module 3. This application does not impose any special limitations on the circuit structure and specific implementation of the amplification module 3 in applications, and there are multiple implementation methods.

[0091] The amplification module 3 is implemented through a three-stage amplification structure consisting of a pre-amplification module, a first level shifting module, a main amplification module, an output amplification module, and a bias current module. This makes the circuit structure of the amplification module 3 clearer and more explicit, effectively realizes the function of the amplification module 3, ensures the amplification factor and high-precision output signal, reduces the transmission delay of the receiver, improves working efficiency, and also ensures the accuracy of the receiver's output results, which is beneficial to the entire reception process of the CAN bus.

[0092] In one preferred embodiment, the amplification module 3 further includes a second level shifting module;

[0093] The first input terminal of the second level shifting module is connected to the first output terminal of the main amplification module, the second input terminal is connected to the second output terminal of the main amplification module, the first output terminal is connected to the first input terminal of the output amplification module, the second output terminal is connected to the second input terminal of the output amplification module, and the third input terminal is connected to the bias current module.

[0094] A second level shifting module is added between the main amplification module and the output amplification module to further ensure the accuracy of the signal received by the output amplification module. This is particularly useful when the amplification module 3 uses transistors, as it can effectively adjust the transistor's bias point, ensuring the accuracy of the output signal. This application does not impose specific limitations on the circuit structure and implementation of the second level shifting module. Figure 4 For example, the first level shifting module is implemented using switching transistors N8 and N9;

[0095] A second level shifting module was added between the main amplification module and the output amplification module. This not only fulfills the function of amplification module 3, but also further improves the accuracy of the amplified signal, ensuring the accuracy and reliability of the output signal of amplification module 3. This guarantees the accuracy of the receiver's output results and facilitates the entire CAN bus reception process.

[0096] In one preferred embodiment, the pre-amplification module includes a first amplification switch N2, a second amplification switch N3, a first protection resistor R13, a second protection resistor R14, a first diode D1, a second diode D2, a third protection resistor R15, and a fourth protection resistor R16.

[0097] The control terminal of the first amplifying switch N2 is connected to the first output terminal of the step-down module 1 and the first terminal of the first protective resistor R13. The second terminal of the first protective resistor R13 is connected to the first terminal of the first amplifying switch N2, the first terminal of the second amplifying switch N3, the first terminal of the second protective resistor R14, and the bias current module. The control terminal of the second amplifying switch N3 is connected to the second output terminal of the step-down module 1 and the second terminal of the second protective resistor R14. The second terminal of the first amplifying switch N2 is connected to the negative terminal of the first diode D1. The second terminal of the second amplifying switch N3 is connected to the negative terminal of the second diode D2. The positive terminal of the first diode D1 is connected to the first terminal of the third protective resistor R15 and the first input terminal of the first level shifting module. The positive terminal of the second diode D2 is connected to the first terminal of the fourth protective resistor R16 and the second input terminal of the first level shifting module. The second terminals of the third protective resistor R15 and the fourth protective resistor R16 are connected to the power supply.

[0098] The pre-amplification module is implemented using a first amplification switch N2, a second amplification switch N3, a first protection resistor R13, a second protection resistor R14, a first diode D1, a second diode D2, a third protection resistor R15, and a fourth protection resistor R16. A first discharge switch, a first protection resistor R13, a first diode D1, and a third protection resistor R15 form one group, and a second discharge switch, a second protection resistor R14, a second diode D2, and a fourth protection resistor R16 form another group. These two groups receive the first and second signals respectively through the first amplification switch N2 and the second amplification switch N3, and amplify the first and second signals. The first protection resistor R13, the second protection resistor R14, the third protection resistor R15, and the fourth protection resistor R16 mainly function as voltage dividers and current limiters, further protecting the circuit. The first diode D1 and the second diode D2 effectively achieve reverse isolation, preventing current backflow caused by power supply instability and ensuring the normal operation of the pre-amplification module.

[0099] Specifically, this application does not impose any particular limitations on the types and specific implementation methods of the first amplification switch N2, the second amplification switch N3, the first protection resistor R13, the second protection resistor R14, the first diode D1, the second diode D2, the third protection resistor R15, and the fourth protection resistor R16. These can be adjusted according to actual needs and applications. The reverse isolation function of the first diode D1 and the second diode D2 can also be achieved by other devices, such as connecting the NPN transistor as a diode to achieve unidirectional conduction. This application does not impose any particular limitations on the specific circuit structure of the pre-amplification module.

[0100] The pre-amplification module is implemented using the first amplification switch N2, the second amplification switch N3, the first protection resistor R13, the second protection resistor R14, the first diode D1, the second diode D2, the third protection resistor R15, and the fourth protection resistor R16. This ensures circuit safety while effectively realizing the amplification function of the pre-amplification module. The entire circuit structure is simple, the components used are easy to implement, and the cost is low. This ensures the normal operation of the amplification module 3, guarantees the accuracy of the receiver's output, improves the reliability and safety of the receiver, and facilitates the entire CAN bus reception process.

[0101] by Figure 3 For example, RXD is the signal output by the amplification module 3, which is fed back to the threshold setting module 2. By adjusting the current source resistor, i.e. whether the first threshold resistor R2 is connected to the circuit, the preset threshold is changed, thereby achieving the purpose of hysteresis control. In addition, the reset signal RST, which is output by the reset module as a stability indicator, can be used to control the mute of the amplification module 3, thereby putting the receiver in mute mode. The method of adjusting the threshold is not limited to this. Adjusting the preset threshold of the receiver by controlling other types of current sources is also within the protection range. Figure 3 Resistor R7 and capacitor C1 form a low-pass filter; resistor R8 and capacitor C2 form a low-pass filter; both serve as filters, which can filter out high-frequency noise in the circuit and further improve the accuracy and reliability of the output signal.

[0102] by Figure 4 For example, in practical applications, to achieve a 70V bus withstand design, the step-down module 1 must step down the high-voltage signal to below 6V to ensure the safety of the first amplification switch N2 and the second amplification switch N3 in the pre-amplification module, preventing them from being damaged. Thus, the minimum differential signal corresponding to amplification module 3 will be as low as 70mV, requiring amplification capability close to 1000 times. The pre-amplification module uses an NPN transistor input structure, with the transistor's load terminal connected to an isolation diode, achieving good reverse isolation. Compared to traditional CMOS input methods, this results in a higher amplification factor, reducing the gain pressure on subsequent stages. The main amplification module handles most of the gain, thus reducing the accuracy requirements of the output amplification module. The output amplification module can use a high-speed comparator structure such as an OTA (operational transconductance amplifier). The second level shift requirement between the main amplification module and the output amplification module is not high, so it can be removed or added.

[0103] Understandable Figure 3 as well as Figure 4The diagram shown is just one specific implementation of the CAN bus receiver. The input signal can also be reversed, and the corresponding subsequent circuit structure is also reversed synchronously. The two signals output by the threshold setting module 2 and the buck module 1 are reversed. The correct output is achieved by inverting the signal in the subsequent stage. There are multiple ways to choose the circuit structure and specific implementation of the buck module 1, the threshold setting module 2 and the amplification module 3. This application does not make any special restrictions here.

[0104] In response to the shortcomings of existing technologies, Figure 3 and Figure 4 For example, this application proposes a CAN bus receiver combining bipolar and CMOS devices to meet the application requirements of high speed and high precision. The implementation of the NPN input pair transistors in the amplification module 3 of this invention can meet higher withstand voltage requirements without affecting accuracy. The pre-amplification module of the receiver mainly uses a first diode D1 and a second diode D2 to isolate the reverse bias current to meet leakage current requirements; the main amplification module of the receiver achieves high gain; the output amplification module of the receiver uses an OTA amplification module to meet high-speed logic level comparison. As a further improvement to the embodiment of this invention, the output amplification module of the receiver can also be implemented using a folded common-source cascode operational amplifier. Followers can be used between the various modules of the receiver to match the inter-stage common-mode levels.

[0105] The hysteresis control method between the threshold setting module 2 and the amplification module 3, and the threshold adjustment method in the threshold setting module 2, in this application can solve the inaccuracy problem of traditional cross-hysteresis comparators and load-adjusting hysteresis comparators. Figure 3 The current stabilization structure in the circuit suppresses current fluctuations in the input current source. This current flows through the step-down module 1 and forms a stable threshold based on Vcm (common-mode voltage), forcing the receiver's monitoring signal to be generated only when the input signal "CANH-CANL" is greater than the preset threshold. This setting method has very high anti-interference stability. At the same time, the hysteresis control method of the current source in the output signal feedback control threshold setting module 2 of the amplifier module 3 will not cause jitter interference to the amplification path after being filtered in the circuit.

[0106] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the structure of a CAN bus signal receiving device provided by the present invention;

[0107] To solve the above-mentioned technical problems, the present invention also provides a CAN bus signal receiving device, including a CAN controller 22 and a CAN bus receiver 21 as described above;

[0108] The CAN controller 22 is connected to the CAN bus receiver 21, and the CAN bus receiver 21 is connected to the CAN bus.

[0109] Generally, the CAN bus receiver 21 converts the differential signal received from the CAN bus into a logic level signal and outputs the logic level signal to the CAN controller 22. The CAN controller 22 then converts the logic level signal into a corresponding processing signal and transmits it to the backend processing module or other remote devices for subsequent processing. Specifically, this application does not impose any particular limitations on the type and implementation of the CAN bus and CAN controller 22. The CAN controller 22 can be a CAN communication chip, etc. Similarly, this application does not impose any particular limitations on the connection method between the CAN controller 22 and the CAN bus receiver 21, or the connection method between the CAN bus receiver 21 and the CAN bus. These can be adjusted according to actual application requirements and the application environment.

[0110] For a description of the CAN bus signal receiving device provided in this application, please refer to the above method embodiments; further details will not be repeated here.

[0111] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0112] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A receiver for a CAN bus, characterized in that, include: The step-down module has a first input terminal connected to the high level of the CAN bus, a second input terminal connected to the low level of the CAN bus, a first output terminal connected to the first input terminal of the amplifier module, and a second output terminal connected to the second input terminal of the amplifier module. The threshold setting module has its input end connected to the output end of the amplification module, and its output end connected to the third input end of the buck module and the third input end of the amplification module, respectively. It is used to cooperate with the buck module to step down the high level of the CAN bus to a first signal output based on a preset threshold, step down the low level of the CAN bus to a second signal output based on the preset threshold, and adjust the preset threshold according to the output signal of the amplification module. The amplification module, whose output terminal serves as the output terminal of the receiver, is used to output a first level when the difference between the first signal and the second signal meets a preset condition; When the difference between the first signal and the second signal does not meet the preset condition, a second level is output, and the first level is opposite to the second level. The threshold setting module includes a reset module, a threshold adjustment module, and an output module; The input terminal of the threshold adjustment module is connected to the output terminal of the amplification module, and the output terminal is connected to the input terminal of the output module. The first terminal of the reset module is connected to the reset signal, and the second terminal is connected to the input terminal of the output module. The output terminal of the output module serves as the output terminal of the threshold setting module. The threshold adjustment module is used to adjust the preset threshold according to the output signal of the amplification module, and transmit the signal corresponding to the preset threshold to the output module; The output module is used in conjunction with the step-down module to step down the high level of the CAN bus to a first signal output based on a preset threshold, and to step down the low level of the CAN bus to a second signal output based on the preset threshold; different preset thresholds correspond to different offset signals, so as to achieve different degrees of step-down of the signals on the CAN bus.

2. The CAN bus receiver as described in claim 1, characterized in that, The step-down module includes a filter capacitor, a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, and a fourth voltage divider resistor; The first terminal of the first voltage divider resistor is connected to the low level of the CAN bus, and the second terminal is connected to the first terminal of the filter capacitor and the first terminal of the second voltage divider resistor. The second terminal of the second voltage divider resistor is connected to the common-mode voltage and the first terminal of the third voltage divider resistor. The second terminal of the third voltage divider resistor is connected to the first terminal of the fourth voltage divider resistor and the second terminal of the filter capacitor. The second terminal of the fourth voltage divider resistor is connected to the high level of the CAN bus. The second terminal of the first voltage divider resistor serves as the first output terminal of the buck module, and the second terminal of the third voltage divider resistor serves as the second output terminal of the buck module.

3. The receiver for the CAN bus as described in claim 1, characterized in that, The reset module includes a first reset switch, a second reset switch, a reset resistor, and an inverter; The first terminal of the first reset switch is connected to the power supply, and the second terminal is connected to the first terminal of the second reset switch. The second terminal of the second reset switch is connected to the input terminal of the inverter and the first terminal of the reset resistor. The output terminal of the inverter is connected to the reset signal. The second terminal of the reset resistor is grounded. The control terminals of the first reset switch and the second reset switch are connected to the input terminal of the output module.

4. The receiver for the CAN bus as described in claim 1, characterized in that, The threshold adjustment module includes a first threshold switch, a second threshold switch, a first threshold resistor, a second threshold resistor, a current source switch, and a first current limiting resistor. The control terminal of the first threshold switch is connected to the output terminal of the amplification module. The first terminal is grounded. The second terminal is connected to the first terminal of the first threshold resistor and the first terminal of the second threshold resistor. The second terminal of the first threshold resistor is grounded. The second terminal of the second threshold resistor is connected to the first terminal of the second threshold switch and the control terminal of the current source switch. The first terminal of the current source switch is connected to the control terminal of the current source and the second threshold switch. The second terminal is connected to the first terminal of the first current limiting resistor. The second terminal of the first current limiting resistor is grounded. The second terminal of the second threshold switch is connected to the input terminal of the output module.

5. The CAN bus receiver as described in claim 3, characterized in that, The output module includes a second current-limiting resistor, a third current-limiting resistor, a first output switch, a second output switch, a third output switch, a fourth output switch, a fifth output switch, a sixth output switch, a seventh output switch, and an eighth output switch. The first terminal of the first output switch is connected to the power supply, and the second terminal is connected to the first terminal of the second output switch. The first terminal of the third output switch is connected to the power supply, and the second terminal is connected to the first terminal of the fourth output switch. The control terminals of the first and third output switches are connected to the control terminals of the first and second reset switches. The control terminals of the second and fourth output switches are connected to the control terminals of the second reset switch. The first terminal of the second current-limiting resistor is connected to the output terminal of the threshold setting module and the control terminal of the second reset switch, respectively. The second terminal is connected to the second terminal of the second output switch and the control terminal of the first reset switch, respectively. The second terminal of the fourth output switch is connected to the first terminal of the third current-limiting resistor, respectively. The control terminals of the fifth and seventh output switches are connected to the control terminals of the fifth, sixth, and eighth output switches, respectively. The second terminal of the fifth output switch is connected to the first terminal of the sixth output switch, and the second terminal of the sixth output switch is grounded. The first terminal of the seventh output switch serves as the output terminal of the output module, and the second terminal is connected to the first terminal of the eighth output switch, and the second terminal of the eighth output switch is grounded.

6. The receiver for the CAN bus as described in any one of claims 1 to 5, characterized in that, The amplification module includes a pre-amplification module, a first level shifting module, a main amplification module, an output amplification module, and a bias current module; The first input terminal of the pre-amplification module is connected to the first output terminal of the buck module, the second input terminal is connected to the second output terminal of the buck module, the first output terminal is connected to the first input terminal of the first level shift module, the second output terminal is connected to the second input terminal of the first level shift module, the first output terminal of the first level shift module is connected to the first input terminal of the main amplification module, the second output terminal of the first level shift module is connected to the second input terminal of the main amplification module, the first output terminal of the main amplification module is connected to the first input terminal of the output amplification module, the second output terminal of the main amplification module is connected to the second input terminal of the output amplification module, the output terminal of the output amplification module serves as the output terminal of the amplification module, and the third input terminal of the pre-amplification module, the third input terminal of the first level shift module, the third input terminal of the main amplification module, and the third input terminal of the output amplification module are respectively connected to the bias current module. The bias current module is used to provide the fixed bias current required for normal operation of the pre-amplification module, the first level shifting module, the main amplification module and the output amplification module; The output amplification module is used to output a high level when the difference between the first signal and the second signal meets a preset condition, and to output a low level when the difference between the first signal and the second signal does not meet the preset condition. The high level is the first level and the low level is the second level.

7. The CAN bus receiver as described in claim 6, characterized in that, The amplification module also includes a second level shifting module; The first input terminal of the second level shifting module is connected to the first output terminal of the main amplification module, the second input terminal is connected to the second output terminal of the main amplification module, the first output terminal is connected to the first input terminal of the output amplification module, the second output terminal is connected to the second input terminal of the output amplification module, and the third input terminal is connected to the bias current module.

8. The receiver for the CAN bus as described in claim 6, characterized in that, The pre-amplification module includes a first amplification switch, a second amplification switch, a first protection resistor, a second protection resistor, a first diode, a second diode, a third protection resistor, and a fourth protection resistor; The control terminal of the first amplifying switch is connected to the first output terminal of the step-down module and the first terminal of the first protective resistor. The second terminal of the first protective resistor is connected to the first terminal of the first amplifying switch, the first terminal of the second amplifying switch, the first terminal of the second protective resistor, and the bias current module. The control terminal of the second amplifying switch is connected to the second output terminal of the step-down module and the second terminal of the second protective resistor. The second terminal of the first amplifying switch is connected to the negative terminal of the first diode. The second terminal of the second amplifying switch is connected to the negative terminal of the second diode. The positive terminal of the first diode is connected to the first terminal of the third protective resistor and the first input terminal of the first level shifting module. The positive terminal of the second diode is connected to the first terminal of the fourth protective resistor and the second input terminal of the first level shifting module. The second terminals of the third and fourth protective resistors are connected to the power supply.

9. A signal receiving device for a CAN bus, characterized in that, Includes a CAN controller and a receiver for the CAN bus as described in any one of claims 1 to 8; The CAN controller is connected to the receiver of the CAN bus, and the receiver of the CAN bus is connected to the CAN bus.

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