CAN isolation transceiver and system

Abstract

The utility model relates to the technical field of signal transmission, in particular to a CAN (Controller Area Network) isolation transceiver and system, and the CAN isolation transceiver comprises a CAN transceiver chip, an EMC (Electro Magnetic Compatibility) protection circuit and a CAN interface, the first end of the CAN transceiver chip is connected with the processing unit, the second end of the CAN transceiver chip is connected with the first end of the EMC protection circuit, and the second end of the EMC protection circuit is connected with the CAN interface; when receiving the CAN sending signal of the processing unit, the CAN transceiver chip converts the CAN sending signal of a common level into a CAN differential signal and transmits the CAN differential signal to the EMC protection circuit; and the EMC protection circuit performs electromagnetic protection processing on the CAN differential signal and transmits the CAN differential signal after electromagnetic protection processing to the CAN interface. Electromagnetic protection processing is carried out on transmission of CAN signals, signal quality reduction and component damage caused by electromagnetic interference are avoided, the transmission quality of the signals is guaranteed, and the propagation distance of the signals is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of signal transmission, in particular to a CAN isolation transceiver and system. Background Art

[0002] Controller Area Network (CAN) bus technology is a serial communication protocol widely used in automotive and industrial control applications. Originally developed by Bosch in Germany in 1986, CAN has evolved over time with technological advancements. Commonly used protocols include CAN 2.0 and the current CAN FD protocol.

[0003] In some applications with harsh electromagnetic environments, such as new energy vehicles and rail transit, strong electromagnetic interference may lead to signal quality degradation, increased error frames, unstable communications, and other problems, affecting the performance and reliability of CAN isolation transceivers, and may even damage components in conventional CAN transmission, posing a threat to the stable operation of the system. Utility Model Content

[0004] The main purpose of the utility model is to provide a CAN isolation transceiver and system, aiming to solve the technical problem in the prior art that CAN signals are easily affected by electromagnetic interference during transmission, which affects the signal transmission capability.

[0005] To achieve the above object, the present invention provides a CAN isolation transceiver, which includes: a CAN transceiver chip, an EMC protection circuit and a CAN interface;

[0006] A first end of the CAN transceiver chip is connected to the processing unit, a second end of the CAN transceiver chip is connected to a first end of the EMC protection circuit, and a second end of the EMC protection circuit is connected to the CAN interface;

[0007] The CAN transceiver chip is configured to, upon receiving the CAN transmission signal from the processing unit, convert the CAN transmission signal of a normal level into a CAN differential signal, and transmit the CAN differential signal to the EMC protection circuit;

[0008] The EMC protection circuit is used to perform electromagnetic protection processing on the CAN differential signal and transmit the CAN differential signal after the electromagnetic protection processing to the CAN interface.

[0009] Optionally, the EMC protection circuit includes: a surge protection unit and an electrostatic protection unit;

[0010] The first end of the surge protection unit is connected to the second end of the CAN transceiver chip, the second end of the surge protection unit is connected to the CAN interface, the third end of the surge protection unit is connected to the signal ground, and the electrostatic protection unit is arranged between the signal ground and the digital ground;

[0011] The surge protection unit is used to perform surge protection processing on the CAN differential signal and transmit the CAN differential signal after the surge protection processing to the CAN interface;

[0012] The electrostatic protection unit is used to enhance the electrostatic protection capability of the CAN interface.

[0013] Optionally, the surge protection unit includes: a first resistor, a second resistor, a first capacitor, a second capacitor, a first diode, a second diode, a third diode and a fourth diode;

[0014] The first end of the first resistor receives the CAN differential high-level signal of the CAN transceiver chip, the first end of the second resistor receives the CAN differential low-level signal of the CAN transceiver chip, the second end of the first resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the signal ground, the second end of the second resistor is connected to the second diode, and the cathode of the second diode is connected to the signal ground, the first end of the first resistor is also connected to the anode of the third diode and one end of the first capacitor, and the cathode of the third diode and the other end of the first capacitor are connected to the signal ground, the first end of the second resistor is also connected to the fourth diode and the second capacitor, and the cathode of the fourth diode and the other end of the second capacitor are connected to the signal ground.

[0015] Optionally, the electrostatic protection unit includes: a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor;

[0016] The CAN interface is also connected to the signal ground and the chassis ground;

[0017] The third capacitor, the fourth capacitor and the fifth capacitor are connected in parallel between the signal ground and the digital ground, and the sixth capacitor, the seventh capacitor and the eighth capacitor are connected in parallel between the chassis ground and the signal ground.

[0018] Optionally, the CAN isolation transceiver further includes: a magnetic bead, a ninth capacitor, and a tenth capacitor;

[0019] The third end of the CAN transceiver chip is connected to the input power supply and one end of the ninth capacitor, the other end of the ninth capacitor is connected to the digital ground, the fourth end of the CAN transceiver chip is connected to one end of the tenth capacitor, the other end of the tenth capacitor is connected to the signal ground, the fourth end of the CAN transceiver chip is also connected to one end of the magnetic bead, the other end of the magnetic bead is connected to the fifth end of the CAN transceiver chip, and the fourth end of the CAN transceiver chip is also connected to the CAN interface.

[0020] Optionally, the CAN isolation transceiver further includes: a terminal resistor and a dip switch;

[0021] The first end of the dip switch receives the CAN differential high level signal of the CAN transceiver chip, the first end of the dip switch is connected to one end of the terminal resistor, and the other end of the terminal resistor is connected to the CAN differential low level signal of the CAN transceiver chip.

[0022] Optionally, the CAN isolation transceiver further includes: a common mode noise suppression unit;

[0023] The common mode noise suppression unit is arranged between the second end of the CAN transceiver chip and the first end of the EMC protection circuit;

[0024] The common-mode noise suppression unit is used to perform common-mode filtering on the CAN differential signal and transmit the CAN differential signal after the common-mode filtering to the EMC protection circuit.

[0025] Optionally, the common mode noise suppression unit includes: a third resistor and a fourth resistor;

[0026] A first end of the third resistor receives a CAN differential high-level signal from the CAN transceiver chip, a second end of the third resistor is connected to the EMC protection circuit, a first end of the fourth resistor receives a CAN differential low-level signal from the CAN transceiver chip, and a second end of the fourth resistor is connected to the EMC protection circuit.

[0027] Optionally, the common-mode noise suppression unit includes: a common-mode inductor;

[0028] The first end of the common-mode inductor receives the CAN differential high-level signal of the CAN transceiver chip, the second end of the common-mode inductor receives the CAN differential low-level signal of the CAN transceiver chip, and the third end and the fourth end of the common-mode inductor are both connected to the EMC protection circuit.

[0029] In addition, to achieve the above-mentioned purpose, the present invention further provides a CAN isolation transceiver system, which includes: at least one CAN isolation transceiver as described above.

[0030] The technical solution of the present utility model proposes a CAN isolation transceiver and system. The CAN isolation transceiver includes: a CAN transceiver chip, an EMC protection circuit, and a CAN interface; the first end of the CAN transceiver chip is connected to a processing unit, the second end of the CAN transceiver chip is connected to the first end of the EMC protection circuit, and the second end of the EMC protection circuit is connected to the CAN interface; when the CAN transceiver chip receives a CAN transmission signal from the processing unit, it generates a CAN differential signal and transmits it to the EMC protection circuit; the EMC protection circuit performs electromagnetic protection processing on the CAN differential signal and transmits the processed CAN differential signal to the CAN interface. By providing an EMC protection circuit to perform electromagnetic protection processing on the transmission of CAN signals, damage to components caused by electromagnetic interference is avoided, the transmission quality of the CAN signal is guaranteed, and the signal propagation distance can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0032] Figure 1 This is a module schematic diagram of the first embodiment of the CAN isolation transceiver of the utility model;

[0033] Figure 2 This is a circuit structure diagram of a surge protection unit in the second embodiment of the CAN isolation transceiver of the present utility model;

[0034] Figure 3 This is a circuit structure diagram of the electrostatic protection unit in the second embodiment of the CAN isolation transceiver of the present utility model;

[0035] Figure 4 This is a circuit diagram of the third embodiment of the CAN isolation transceiver of the present utility model;

[0036] Figure 5 This is a circuit structure diagram of a common-mode noise suppression unit in the third embodiment of the CAN isolation transceiver of the present utility model;

[0037] Figure 6 This is a functional module diagram of an embodiment of a CAN isolated transceiver system of the present invention.

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0043] Reference Figure 1 , Figure 1 This is a module diagram of the first embodiment of the CAN isolation transceiver of the present utility model.

[0044] The utility model provides a first embodiment of a CAN isolation transceiver.

[0045] In this embodiment, the CAN isolation transceiver includes a CAN transceiver chip 10, an EMC protection circuit 20 and a CAN interface 30; the first end of the CAN transceiver chip 10 is connected to the processing unit, the second end of the CAN transceiver chip 10 is connected to the first end of the EMC protection circuit 20, and the second end of the EMC protection circuit is connected to the CAN interface 30.

[0046] It should be noted that the CAN transceiver chip 10 can be used to convert the CAN transmission signal of normal level into a CAN differential signal when receiving the CAN transmission signal from the processing unit, and transmit the CAN differential signal to the EMC protection circuit 20; the EMC protection circuit 20 can be used to perform electromagnetic protection processing on the CAN differential signal, and transmit the CAN differential signal after electromagnetic protection processing to the CAN interface 30.

[0047] Among them, the CAN transceiver chip 10 can use the NSIP1042 chip, which can support a maximum data transmission rate of 5Mbps. Therefore, it can simultaneously support CAN2.0 (CAN standard message format) and CAN FD (variable rate CAN) modes, and the insulation voltage can reach 5000Vrms, with good EMC protection performance.

[0048] It should be understood that the processing unit can be an electronic component with signal transmission and data processing functions, capable of performing data processing functions according to pre-set programming software and transmitting the calculation results in the form of electrical signals. For example, a central processing unit (CPU) or a microcontroller unit (MCU) can be used. The processing unit can generate a TTL level (a logic level standard, +5V is equivalent to logic 1, 0V is equivalent to logic 0) CAN TX (transmit signal) to the CAN transceiver chip 10 according to a preset program, and can also receive a CAN RX (receive signal) from the CAN transceiver chip 10. The CAN transceiver chip 10 can convert the TTL level CAN transmit signal into a CAN differential signal (CANH / CANL). When the voltage of CANH is higher than CANL, it is in the dominant state and transmits logic "0". When the voltage of CANH is equal to CANL, it is in the recessive state and transmits logic "1", thereby realizing the logic level signal transmission function, transmitting data using differential signals, improving the reliability of data transmission, and reducing electromagnetic interference.

[0049] Furthermore, electromagnetic compatibility (EMC) can be defined as the ability of a device or system to operate normally within its electromagnetic environment without causing unacceptable electromagnetic interference to other devices in the environment. This can be broadly categorized into two types: electromagnetic interference (EMI), which refers to the impact of a device's own electromagnetic noise on other devices or the human body; and electromagnetic susceptibility (EMS), which refers to whether a device may malfunction due to external electromagnetic interference.

[0050] It should be understood that the EMC protection circuit 20 may include: a surge protection unit 201 and an electrostatic protection unit 202. The first end of the surge protection unit 201 is connected to the second end of the CAN transceiver chip 10, the second end of the surge protection unit 201 is connected to the CAN interface 30, the third end of the surge protection unit 201 is connected to the signal ground, and the electrostatic protection unit 202 is provided between the signal ground and the digital ground.

[0051] The surge protection unit 201 may be used to perform surge protection on the CAN differential signal and transmit the surge-protected CAN differential signal to the CAN interface 30 ; the electrostatic protection unit 202 may be used to enhance the electrostatic protection capability of the CAN interface 30 .

[0052] It should be noted that the signal ground can be the ground for analog signals, and the digital ground can be the ground for TTL digital level signals. Surges can be transient overvoltages or overcurrents in which the signal voltage amplitude exceeds the normal operating voltage. The surge protection unit 201 can quickly respond to transient voltages to protect components from damage. For example, transient voltage suppressors (TVS) diodes and fuses can be used. The electrostatic protection unit 202 can isolate the signal ground from the analog ground to avoid the generation of static electricity. For example, high-voltage capacitors or MOS tubes can be used. Since the CAN interface often comes into contact with the human body, the electrostatic protection unit 202 can be set close to the CAN interface to enhance the protection capability of the circuit.

[0053] This embodiment proposes a CAN isolation transceiver, which includes a CAN transceiver chip, an EMC protection circuit, and a CAN interface. The first end of the CAN transceiver chip is connected to a processing unit, the second end of the CAN transceiver chip is connected to the first end of the EMC protection circuit, and the second end of the EMC protection circuit is connected to the CAN interface. Upon receiving a CAN transmit signal from the processing unit, the CAN transceiver chip generates a CAN differential signal and transmits it to the EMC protection circuit. The EMC protection circuit performs electromagnetic protection processing on the CAN differential signal and transmits the processed CAN differential signal to the CAN interface. By providing the EMC protection circuit with electromagnetic protection processing for CAN signal transmission, signal quality degradation and component damage caused by electromagnetic interference are avoided, thereby ensuring CAN signal transmission quality and extending the signal propagation distance.

[0054] Reference Figure 2 and Figure 3 , Figure 2 This is a circuit diagram of a surge protection unit in the second embodiment of the CAN isolation transceiver of the present utility model. Figure 3The second embodiment of the CAN isolation transceiver of the present invention is proposed based on the first embodiment of the CAN isolation transceiver.

[0055] In this embodiment, the surge protection unit 201 includes a first resistor R1 , a second resistor R2 , a first capacitor C1 , a second capacitor C2 , and first to fourth diodes ( D1 ˜ D4 ).

[0056] Among them, the first end of the first resistor R1 receives the CAN differential high-level signal (CANH) of the CAN transceiver chip 10, the first end of the second resistor R2 receives the CAN differential low-level signal (CANL) of the CAN transceiver chip 10, the second end of the first resistor R1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the signal ground. The second end of the second resistor R2 is connected to the second diode D2, and the cathode of the second diode D2 is connected to the signal ground. The first end of the first resistor R1 is also connected to the anode of the third diode D3 and one end of the first capacitor C1, and the cathode of the third diode D3 and the other end of the first capacitor C1 are connected to the signal ground. The first end of the second resistor R2 is also connected to the fourth diode D4 and the second capacitor C2, and the cathode of the fourth diode D4 and the other end of the second capacitor C2 are connected to the signal ground.

[0057] It should be noted that the first and second diodes D1 and D2 can be thyristor surge suppressors (TSSs), which utilize the breakdown characteristics of a four-layer semiconductor structure. When the applied voltage is below the off-state voltage, the TSS is in the off-state. When the voltage exceeds the maximum off-state voltage, the TSS clamps the transient voltage to within the breakover voltage and enters the on-state, effectively short-circuiting. When the voltage returns to normal, the components turn off, providing overvoltage protection during signal transmission. The third and fourth diodes D3 and D4 can be bidirectional TVS diodes, which utilize the PN junction avalanche breakdown principle. When the reverse voltage exceeds the breakdown voltage, the TVS rapidly changes from high impedance to low impedance, quickly absorbing transient high-voltage spikes and clamping the abnormal voltage to a low level, thereby protecting the circuit. Furthermore, due to its bidirectional transient voltage suppression, it can protect bipolar lines such as CAN. The first and second resistors R1 and R2 can be packaged in 0805 sizes for high current.

[0058] Furthermore, the electrostatic protection unit 202 includes: third to eighth capacitors (C3~C8); the CAN interface 30 is also connected to the signal ground and the chassis ground at the same time; wherein, the third to fifth capacitors (C3~C5) are arranged in parallel between the signal ground and the digital ground, and the sixth to eighth capacitors (C6~C8) are arranged in parallel between the chassis ground and the signal ground.

[0059] The chassis ground refers to the connection between the metal casing of an electronic device and the ground or grounding system. It is typically used to provide lightning protection and shield the device from external electromagnetic interference. The third through eighth capacitors (C3-C8) can all be high-voltage capacitors (e.g., 1000pF) to isolate the signal ground from the digital ground, and the signal ground (GND_CAN) from the chassis ground (GND_SHIELD).

[0060] This embodiment provides a surge protection unit comprising a first resistor, a second resistor, a first capacitor, a second capacitor, and first to fourth diodes to perform surge protection on CAN differential signals and transmit the processed CAN differential signals to the CAN interface. Furthermore, an electrostatic protection unit comprising third to eighth capacitors is provided to enhance the electrostatic protection capability of the CAN interface. This further protects the transmission of CAN signals, ensuring signal quality and transmission distance.

[0061] Reference Figure 4 , Figure 4 The third embodiment of the CAN isolation transceiver of the present invention is a circuit diagram of the third embodiment of the CAN isolation transceiver of the present invention.

[0062] In this embodiment, the CAN isolation transceiver further includes a magnetic bead FB1 , a ninth capacitor C9 , and a tenth capacitor C10 .

[0063] Among them, the third end of the CAN transceiver chip 10 is connected to the input power supply VCC and one end of the ninth capacitor C9, the other end of the ninth capacitor C9 is connected to the digital ground, the fourth end of the CAN transceiver chip 10 is connected to one end of the tenth capacitor C10, the other end of the tenth capacitor C10 is connected to the signal ground, the fourth end of the CAN transceiver chip 10 is also connected to one end of the magnetic bead FB1, the other end of the magnetic bead FB1 is connected to the fifth end of the CAN transceiver chip 10, and the fourth end of the CAN transceiver chip 10 is also connected to the CAN interface 30 (the CAN interface is powered by the VCC1 port in the figure).

[0064] It should be noted that the ninth capacitor C9 and the tenth capacitor C10 can both be composed of a 10uf and a 0.1uf capacitor in parallel (not shown in the figure). The NSIP1042 chip has an integrated isolated DC-DC power converter, which can be powered by a typical 5V input. The third end of the chip is the power input pin (refer to the VDD pin in the figure), and the input power VCC is transmitted to the CAN transceiver chip after filtering through the ninth capacitor C9. The fourth end of the chip is the DC power output pin (refer to the OUT pin in the figure), which can power the CAN interface 30 after filtering through the tenth capacitor C10. The magnetic bead FB1 can be used to suppress high-frequency noise and spike interference in the circuit, and also has the ability to absorb electrostatic pulses. The DC power output pin is connected to the feedback pin (refer to FB in the figure) at the fifth end of the chip through the magnetic bead, which serves to isolate the 5V power supply.

[0065] Furthermore, the CAN isolation transceiver also includes: a terminal resistor R0 and a dip switch SW1; the first end of the dip switch SW1 receives the CAN differential high-level signal of the CAN transceiver chip 10, the first end of the dip switch SW1 is connected to one end of the terminal resistor R0, and the other end of the terminal resistor R0 is connected to the CAN differential low-level signal of the CAN transceiver chip 10.

[0066] It should be understood that in order to improve the anti-interference capability of the CAN bus, quickly pass high-frequency, low-energy signals, and reduce the impact of signal reflections and transmission line parasitic capacitance, a 120Ω terminal resistor R0 can be connected in series between CANH and CANL. The CANH and CANL signals connect the terminal resistor R0 to the signal line via the DIP switch SW1. In the default application, the DIP switch SW1 needs to be turned ON to connect the terminal resistor R0. If the external CAN device has an internal matching terminal resistor R0, or if signal transmission abnormalities are found when connecting multiple devices, try turning the DIP switch to the OFF state to disconnect the terminal resistor R0.

[0067] Further, refer to Figure 5 , Figure 5 This is a circuit structure diagram of the common-mode noise suppression unit in the third embodiment of the CAN isolation transceiver of the present invention. The CAN isolation transceiver also includes: a common-mode noise suppression unit 40; the common-mode noise suppression unit 40 is arranged between the second end of the CAN transceiver chip 10 and the first end of the EMC protection circuit 20.

[0068] It should be noted that the common-mode noise suppression unit 40 can be used to perform common-mode filtering on the CAN differential signal, and transmit the CAN differential signal (CANH1 / CANL1) after the common-mode filtering to the EMC protection circuit 20.

[0069] In one possible implementation, the common-mode noise suppression unit 40 includes: a third resistor R3 and a fourth resistor R4; a first end of the third resistor R3 receives a CAN differential high-level signal from the CAN transceiver chip 10, and a second end of the third resistor R3 is connected to the EMC protection circuit 20; a first end of the fourth resistor R4 receives a CAN differential low-level signal from the CAN transceiver chip 10, and a second end of the fourth resistor R4 is connected to the EMC protection circuit 20.

[0070] In another possible implementation, the common-mode noise suppression unit 40 includes: a common-mode inductor L1; a first end of the common-mode inductor L1 receives a CAN differential high-level signal from the CAN transceiver chip 10, a second end of the common-mode inductor L1 receives a CAN differential low-level signal from the CAN transceiver chip 10, and a third end and a fourth end of the common-mode inductor L1 are both connected to the EMC protection circuit 20.

[0071] It should be noted that before the CANH and CANL signals pass through the EMC protection circuit, common-mode inductors are required to remove common-mode noise and improve signal quality. Common-mode inductors help reduce signal distortion and crosstalk, and improve signal reliability and transmission rate. At the same time, in order to facilitate later debugging in the circuit design, there is a reserved position for 0-ohm resistors (the third resistor R3 and the fourth resistor R4). They are parallel to the common-mode inductor L1. The two can share a pad and cannot be installed at the same time. The 0-ohm resistor also has the effect of partially filtering out common-mode noise, but the effect is not as good as the common-mode inductor. Therefore, this solution defaults to installing the common-mode inductor and not the 0Ω resistor (the common-mode inductor can also be disconnected and the 0-ohm resistor connected as a backup solution).

[0072] This embodiment employs a common-mode noise suppression unit between the second terminal of the CAN transceiver chip and the first terminal of the EMC protection circuit to perform common-mode filtering on the CAN differential signal. The filtered CAN differential signal is then transmitted to the EMC protection circuit. This helps reduce signal distortion and crosstalk, removes common-mode noise, and improves signal quality. A 0-ohm resistor can be used to implement the common-mode noise suppression unit, facilitating debugging of the CAN isolated transceiver. A common-mode inductor can also be used to improve signal reliability and transmission distance.

[0073] In addition, the present invention also provides a CAN isolation transceiver system, referring to Figure 6 , Figure 6 This is a functional module diagram of an embodiment of a CAN isolation transceiver system of the present invention. The CAN isolation transceiver system includes at least one of the above-mentioned CAN isolation transceivers.

[0074] Among them, since the data transmission rate of the CAN isolation transceiver can reach 5Mbps when using NSIP1042, and it can support both CAN2.0 and CAN FD modes, multiple CAN isolation transceivers can be set in the CAN isolation transceiver system, that is, it contains multiple CAN interfaces, and multiple CAN communication devices can be connected to the outside at the same time.

[0075] Since the CAN isolated transceiver system adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0076] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the utility model concept, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A CAN isolation transceiver, characterized in that: The CAN isolation transceiver includes: a CAN transceiver chip, an EMC protection circuit and a CAN interface; A first end of the CAN transceiver chip is connected to the processing unit, a second end of the CAN transceiver chip is connected to a first end of the EMC protection circuit, and a second end of the EMC protection circuit is connected to the CAN interface; The CAN transceiver chip is configured to, upon receiving the CAN transmission signal from the processing unit, convert the CAN transmission signal of a normal level into a CAN differential signal, and transmit the CAN differential signal to the EMC protection circuit; The EMC protection circuit is used to perform electromagnetic protection processing on the CAN differential signal and transmit the CAN differential signal after the electromagnetic protection processing to the CAN interface.

2. The CAN isolation transceiver according to claim 1, wherein: The EMC protection circuit includes: a surge protection unit and an electrostatic protection unit; The first end of the surge protection unit is connected to the second end of the CAN transceiver chip, the second end of the surge protection unit is connected to the CAN interface, the third end of the surge protection unit is connected to the signal ground, and the electrostatic protection unit is arranged between the signal ground and the digital ground; The surge protection unit is used to perform surge protection processing on the CAN differential signal and transmit the CAN differential signal after the surge protection processing to the CAN interface; The electrostatic protection unit is used to enhance the electrostatic protection capability of the CAN interface.

3. The CAN isolation transceiver according to claim 2, wherein: The surge protection unit includes: a first resistor, a second resistor, a first capacitor, a second capacitor, a first diode, a second diode, a third diode and a fourth diode; The first end of the first resistor receives the CAN differential high-level signal of the CAN transceiver chip, the first end of the second resistor receives the CAN differential low-level signal of the CAN transceiver chip, the second end of the first resistor is connected to the anode of the first diode, and the cathode of the first diode is connected to the signal ground, the second end of the second resistor is connected to the second diode, and the cathode of the second diode is connected to the signal ground, the first end of the first resistor is also connected to the anode of the third diode and one end of the first capacitor, and the cathode of the third diode and the other end of the first capacitor are connected to the signal ground, the first end of the second resistor is also connected to the fourth diode and the second capacitor, and the cathode of the fourth diode and the other end of the second capacitor are connected to the signal ground.

4. The CAN isolation transceiver according to claim 2, wherein: The electrostatic protection unit includes: a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor; The CAN interface is also connected to the signal ground and the chassis ground; The third capacitor, the fourth capacitor and the fifth capacitor are connected in parallel between the signal ground and the digital ground, and the sixth capacitor, the seventh capacitor and the eighth capacitor are connected in parallel between the chassis ground and the signal ground.

5. The CAN isolation transceiver according to claim 1, wherein: The CAN isolation transceiver further includes: a magnetic bead, a ninth capacitor and a tenth capacitor; The third end of the CAN transceiver chip is connected to the input power supply and one end of the ninth capacitor, the other end of the ninth capacitor is connected to the digital ground, the fourth end of the CAN transceiver chip is connected to one end of the tenth capacitor, the other end of the tenth capacitor is connected to the signal ground, the fourth end of the CAN transceiver chip is also connected to one end of the magnetic bead, the other end of the magnetic bead is connected to the fifth end of the CAN transceiver chip, and the fourth end of the CAN transceiver chip is also connected to the CAN interface.

6. The CAN isolation transceiver according to claim 5, wherein: The CAN isolation transceiver also includes: a terminal resistor and a dip switch; The first end of the dip switch receives the CAN differential high level signal of the CAN transceiver chip, the first end of the dip switch is connected to one end of the terminal resistor, and the other end of the terminal resistor is connected to the CAN differential low level signal of the CAN transceiver chip.

7. The CAN isolation transceiver according to claim 1, wherein: The CAN isolation transceiver further includes: a common mode noise suppression unit; The common mode noise suppression unit is arranged between the second end of the CAN transceiver chip and the first end of the EMC protection circuit; The common-mode noise suppression unit is used to perform common-mode filtering on the CAN differential signal and transmit the CAN differential signal after the common-mode filtering to the EMC protection circuit.

8. The CAN isolation transceiver according to claim 7, wherein: The common mode noise suppression unit includes: a third resistor and a fourth resistor; A first end of the third resistor receives a CAN differential high-level signal from the CAN transceiver chip, a second end of the third resistor is connected to the EMC protection circuit, a first end of the fourth resistor receives a CAN differential low-level signal from the CAN transceiver chip, and a second end of the fourth resistor is connected to the EMC protection circuit.

9. The CAN isolation transceiver according to claim 7, wherein: The common mode noise suppression unit includes: a common mode inductor; The first end of the common-mode inductor receives the CAN differential high-level signal of the CAN transceiver chip, the second end of the common-mode inductor receives the CAN differential low-level signal of the CAN transceiver chip, and the third end and the fourth end of the common-mode inductor are both connected to the EMC protection circuit.

10. A CAN isolated transceiver system, characterized in that: The CAN isolation transceiver system includes: at least one CAN isolation transceiver according to any one of claims 1-9.

Images