Control circuit and method for optimizing electromagnetic interference and work cycle

Abstract

The invention discloses a control circuit for optimizing electromagnetic interference and a work cycle. The control circuit comprises a slope control module, a rising edge compensation module, a falling edge compensation module and a voltage-controlled current module, in an LIN node conversion falling time stage, a falling edge compensation module receives a battery voltage and converts the battery voltage into a bias current I1 in direct proportion to the battery voltage, a slope control module receives a communication signal and the bias current I1, outputs a slope voltage in direct proportion to the battery voltage, and receives the slope voltage through a voltage-controlled current module. The discharge current is in direct proportion to the battery voltage and is transmitted to the LIN port network; in the LIN node conversion rising time stage, bias current I2 is generated through the rising edge compensation module, communication signals and the bias current I2 are received through the slope control module, fixed slope voltage is output, the slope voltage is received through the voltage-controlled current module, the slope voltage is converted into fixed discharge current, and the fixed discharge current is transmitted to an LIN port network.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor design, and more specifically, relates to a control circuit and method for optimizing electromagnetic interference (EMI) and duty cycle in LIN communication, which has strong practical significance for automotive LIN communication. Background Art

[0002] Currently, with the increasing degree of electrification and intelligence of automobiles, the corresponding electromagnetic interference has become more and more serious, which poses a great challenge to the EMI of in-vehicle electronic systems. In particular, in-vehicle communication also faces great challenges. On the one hand, it is necessary to enhance the electromagnetic susceptibility (EMS) of the electronic system, and on the other hand, it is necessary to reduce the source of EMI. LIN communication is one of the commonly used communication methods in current in-vehicle systems, and it is necessary to meet the LIN communication protocol consistency requirements to achieve high-quality LIN communication.

[0003] Figure 1-1 is the EMI limiting curve of the LIN communication bus filter (IEC 62228 protocol specification). Since the LIN communication rate is relatively low and the bus frequency is 10 kHz, the EMI is mainly distributed at lower frequencies. The IEC 62228 protocol specification requires that the high-frequency components of LIN communication need to be lower than the EMI limiting curve.

[0004] Table 1 shows the LIN communication physical layer consistency requirement parameters (ISO17987-4 protocol specification). The protocol stipulates that the LIN drive signal dominant and recessive duty cycles of the transceiver need to meet the consistency requirements to ensure that other nodes can normally decode the communication.

[0005] Table 1 LIN Communication Physical Layer Consistency Requirement Parameters

[0006] Figure 1-2It is a typical application diagram of LIN communication, which is divided into two modules according to functions. One module is the LIN transmission channel module, which is integrated inside the LIN communication interface chip and consists of a BUFFER circuit, a current-limiting resistor R1, a pull-down transistor M1, and an anti-backflow diode D1; the other module is the LIN port network, which belongs to the chip peripheral application circuit and is specified by the LIN communication physical layer protocol ISO17987 and consists of a node capacitor C1, a pull-up resistor R2, and an anti-backflow diode D2. The working principle is as follows: the LIN transmission channel receives the communication signal sent by the host computer, enhances the driving ability through the BUFFER, and then controls the opening and closing speed of the pull-down transistor M1 through the current-limiting resistor R1. When the pull-down transistor M1 is turned off, the LIN port network pulls up the LIN node to VBAT (ignoring the forward voltage drop of the diode) through the pull-up resistor R2. When the pull-down transistor M1 is closed, the LIN node is pulled down to GND, thus converting the communication signal into the communication signal of the LIN node. In addition, adding the anti-backflow diode D2 can prevent the GND current from flowing back to the LIN bus when the LIN node voltage appears negative, affecting the LIN communication function. Similarly, adding the anti-backflow diode D2 can prevent the reverse current from flowing into VBAT when the LIN voltage is higher than VBAT, causing system anomalies.

[0007] Figure 1-3 It is the second implementation method of the typical application diagram of LIN communication. Similarly, LIN communication can be divided into a LIN transmission channel module and a LIN port network. The difference from Figure 1-2 is that by introducing a slope control circuit to adjust the rise and fall times of the communication signal, the LIN terminal signal is made to follow the communication signal using the principle of feedback. The working principle is as follows: the LIN transmission channel receives the communication signal sent by the host computer. When it detects that TXD is high, it turns off the pull-down transistor M1, and the LIN port network pulls up the LIN node to VBAT (ignoring the forward voltage drop of the diode) through the pull-up resistor R2; when it detects that the communication signal is low, it turns on the pull-down transistor M1 and pulls down the LIN node to GND, thus converting the communication signal into the communication signal of the LIN node.

[0008] From Figure 1-2 the analysis, it can be seen that (1) By controlling the opening and closing speed of the pull-down transistor M1 through the current-limiting resistor R1, the EMI performance can be optimized to a certain extent. However, due to the large process deviation of the internal resistance accuracy of the chip and the parasitic capacitance of the pull-down transistor M1, it is difficult to ensure that the EMI performance and duty cycle of mass-produced products meet the LIN communication ISO17987 consistency requirements; (2) It does not compensate for the LIN communication ISO17987 consistency problem caused by the change range of VBAT.

[0009] From Figure 1-3Analysis shows that (1) By introducing a feedback mechanism to eliminate the influence of VBAT and enabling the LIN node to follow the communication signal. However, since LIN communication is a digital signal and the operational amplifier operates in a switching mode, it is difficult to ensure that the LIN node voltage follows the communication signal, and it is hard to guarantee that the EMI performance and duty cycle meet the LIN communication ISO17987 compliance requirements. (2) Since the LIN operating voltage range is ±40V and the positive terminal of the operational amplifier OP is connected to the LIN pin, it is easy to cause damage to the internal components of the operational amplifier OP. In summary, the existing technology does not eliminate the influence of the battery voltage VBAT variation range and process deviation on the EMI and LIN communication compliance, and it is difficult to meet the EMI highest level class Ⅲ (IEC 62228) and LIN communication compliance requirements (ISO17987). SUMMARY OF THE INVENTION

[0010] To solve the problem of the influence of the battery voltage VBAT variation range and process deviation on the EMI and LIN communication compliance, the present invention provides a control circuit and method for optimizing electromagnetic interference and duty cycle. By means of compensation and cancellation, the influence of the battery voltage VBAT variation on the EMI and duty cycle is eliminated, so that the EMI can reach class Ⅲ and the duty cycle meets the LIN communication compliance requirements.

[0011] According to one aspect of the specification of the present invention, a control circuit for optimizing electromagnetic interference and duty cycle is provided, including a slope control module, a rising edge compensation module, a falling edge compensation module, and a voltage-controlled current module; During the LIN node transition falling time stage, the falling edge compensation module receives the battery voltage and converts it into a bias current I1 proportional to the battery voltage. The slope control module receives the communication signal and the bias current I1 and outputs a slope voltage proportional to the battery voltage. The voltage-controlled current module receives the slope voltage and converts it into a discharge current proportional to the battery voltage, which is transmitted to the LIN port network; During the LIN node transition rising time stage, the rising edge compensation module generates a bias current I2. The slope control module receives the communication signal and the bias current I2 and outputs a fixed slope voltage. The voltage-controlled current module receives the slope voltage and converts it into a fixed discharge current, which is transmitted to the LIN port network.

[0012] As a further technical solution, the rising edge compensation module accesses a reference voltage through a first operational amplifier, and uses the virtual short principle of the operational amplifier to apply the reference voltage to a first resistor to form a current, which is input to a first current mirror through a first current leak and converted into a fixed bias current I2.

[0013] As a further technical solution, the first resistor is a zero-temperature-drift resistor.

[0014] As a further technical solution, the falling-edge compensation module receives the battery voltage, divides the battery voltage through a voltage-dividing resistor and inputs it to a second operational amplifier, and applies the battery voltage to a second resistor by using the virtual-short principle of the operational amplifier to form a current, which passes through a second current leakage and is converted into a bias current I1 proportional to the battery voltage.

[0015] As a further technical solution, the slope control module includes an upper power transistor, a lower power transistor and a capacitor. The gates of the upper power transistor and the lower power transistor are respectively connected to a communication signal, and the drains are commonly connected to the capacitor and a voltage-controlled current module, and the other end of the capacitor is grounded; the source of the upper power transistor is connected to the bias current I1, and the source of the lower power transistor is connected to the bias current I2.

[0016] As a further technical solution, the voltage-controlled current module accesses the output voltage of the slope control module through a third operational amplifier, and applies the output voltage to a third resistor by using the virtual-short principle of the operational amplifier to form a current, which passes through a third current leakage and is input to a second current mirror and is converted into a discharge current following the output voltage.

[0017] According to one aspect of the specification of the present invention, a LIN communication interface chip is provided, which is configured with the control circuit for optimizing electromagnetic interference and duty cycle.

[0018] According to one aspect of the specification of the present invention, a LIN communication system is provided, which includes a LIN port network and a LIN transmission channel module connected to the LIN port network, and the LIN transmission channel module is implemented by using the control circuit for optimizing electromagnetic interference and duty cycle.

[0019] According to one aspect of the specification of the present invention, a control method for optimizing electromagnetic interference and duty cycle is provided, including: In the LIN node transition falling time stage, receiving the battery voltage and converting it into a bias current I1 proportional to the battery voltage, performing slope control on the communication signal and the bias current I1 and outputting a slope voltage proportional to the battery voltage, converting the slope voltage into a discharge current proportional to the battery voltage, and transmitting it to the LIN port network; In the LIN node transition rising time stage, receiving a reference voltage and converting it into a bias current I2, performing slope control on the communication signal and the bias current I2 and outputting a fixed slope voltage, converting the slope voltage into a fixed discharge current, and transmitting it to the LIN port network.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention eliminates the influence of VBAT variation on EMI and duty cycle through a compensation and cancellation method, enabling the EMI to reach Class III level and the duty cycle to meet the consistency requirements of LIN communication.

[0021] 2. The present invention is simple to implement, controls high voltage with low voltage, and has a small area.

[0022] 3. The present invention is less affected by process variations. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1-1 It is a schematic diagram of the EMI limiting curve of the LIN communication bus filter in the prior art.

[0025] Figure 1-2 It is a typical application diagram of LIN communication in the prior art.

[0026] Figure 1-3 It is another typical application diagram of LIN communication in the prior art.

[0027] Figure 1-4 It is a schematic diagram of the circuit structure principle provided by the embodiment of the present invention.

[0028] Figure 1-5 It is a schematic diagram of the LIN communication waveform provided by the embodiment of the present invention.

[0029] Figure 1-6 It is an example diagram of the specific implementation of the falling edge compensation module provided by the embodiment of the present invention.

[0030] Figure 1-7 It is an example diagram of the specific implementation of the rising edge compensation module provided by the embodiment of the present invention.

[0031] Figure 1-8 It is an example diagram of the specific implementation of the slope control module provided by the embodiment of the present invention.

[0032] Figure 1-9 It is an example diagram of the specific implementation of the voltage-controlled current module provided by the embodiment of the present invention.

[0033] Figure 1-10 It is a schematic diagram of the duty cycle simulation waveform provided by the embodiment of the present invention.

[0034] Figure 1-11Schematic diagram of LIN node EMI simulation waveform provided by the embodiments of the present invention. Detailed implementation manners

[0035] Considering that the prior art fails to eliminate the influence of the variation range of the battery voltage VBAT and process deviations on the consistency between EMI and LIN communication, it is difficult to meet the requirements of the highest EMI level class Ⅲ (IEC 62228) and LIN communication consistency (ISO17987). The present invention provides a control circuit for optimizing electromagnetic interference (EMI) and duty cycle in LIN communication to solve the following two problems: 1. To make the EMI in LIN communication reach the highest level class Ⅲ; 2. To make the duty cycle meet the requirements of LIN communication consistency and be unaffected by the variation of the battery voltage VBAT and process deviations. The technical concept of the present invention is to eliminate the influence of VBAT variation on EMI and duty cycle by means of compensation and cancellation, so that the EMI can reach class Ⅲ and the duty cycle can meet the consistency requirements of LIN communication.

[0036] Regarding the terms mentioned in the specification of the present invention, it should be noted that: VBAT: Battery voltage duty cycle: Duty cycle TXD: Communication signal TF: LIN node transition fall time TR: LIN node transition rise time EMS: Electro Magnetic Susceptibility, electromagnetic susceptibility EMI: Electro Magnetic Interference, electromagnetic interference LIN: Local Interconnect Network, local communication network

[0037] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. In addition, the technical features in each embodiment or a single embodiment provided by the present invention can be combined with each other arbitrarily to form a new technical solution. This combination is not restricted by the order of steps and / or the mode of structural composition, but must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0038] The embodiments of the present invention provide a control circuit and method for optimizing electromagnetic interference and duty cycle. By means of an internal battery voltage VBAT compensation algorithm, the influence of VBAT variation on the duty cycle can be better eliminated, a better compromise between the duty cycle and EMI can be achieved, and the designed circuit can take into account both EMI class Ⅲ and good communication quality of the LIN communication duty cycle.

[0039] Figure 1-4 The circuit structure schematic diagram of the embodiments of the present invention is given. Through the analysis of the prior art, the inventor determined that to eliminate the influence of VBAT and ensure TR = TF, the EMI requirements and the LIN communication consistency requirements can be met. Figure 1-4 In [description], the LIN transmission channel module consists of a slope control module, a rising edge compensation module, a falling edge compensation module and a voltage-controlled current module. During the LIN node transition falling time TF stage, through the falling edge compensation module, the VBAT voltage is received and converted into a bias current I1 proportional to the VBAT voltage. The slope control module receives the TXD signal and the bias current I1 and outputs a slope voltage VXTN proportional to VBAT. The voltage-controlled current module receives the modulated slope voltage VXTN and converts it into a discharge current Idischarge proportional to VBAT, thereby compensating and offsetting the influence of the VBAT variable on the LIN transition falling time TF, that is, the falling time TF is fixed under different VBATs.

[0040] Similarly, during the rising time TR of the LIN node conversion, a zero-temperature-drift bias current I2 is generated by the rising edge compensation module. The slope control module receives the TXD signal and the bias current I2, and outputs a fixed-slope voltage VXTN. The voltage-controlled current module receives the modulated slope voltage VXTN and converts it into a fixed discharge current Idischarge, which is equivalent to increasing the LIN conversion rising time TR, making TR = TF, and achieving that the duty cycle meets the LIN communication consistency requirements. Adjust the values of the rising time TR and the falling time TF to meet the EMI requirements.

[0041] Based on the foregoing description of the circuit principle, the control idea of the embodiment of the present invention is to compensate and offset the influence of the VBAT change on the EMI and the duty cycle. By adjusting the rising time and the falling time, ensure that the rising time and the falling time are consistent, so that the EMI can reach class Ⅲ and the duty cycle meets the LIN communication consistency requirements.

[0042] As Figure 1-5 shown, when receiving the TXD input signal during LIN communication, within the first cycle T1, the prior art implementation does not compensate for VBAT. Therefore, the rising time TR of the LIN node conversion depends on the time constant R2C1 composed of the pull-up resistor R2 and the bus capacitor C1 of the LIN port network, that is, TR = 5 × R2C1 (5 time constants are close to the stable time); And the falling time TF of the LIN node conversion is C1 × VBAT / Idischarge. It can be seen from the formula that the falling time TR is related to VBAT; as VBAT increases, it will cause the falling time TR to increase by △T, resulting in a large change in the duty cycle and unable to meet the LIN communication consistency requirements.

[0043] The second cycle is the waveform diagram of the LIN node after introducing the compensation of the embodiment of the present invention. The rising time TR = the falling time TF, and the duty cycle meets the LIN communication consistency requirements. Adjust the values of the rising time TR and the falling time TF to meet the EMI requirements.

[0044] Figure 1-6 is an example diagram of the specific implementation of the falling edge compensation module. Its main function is to receive the VBAT voltage and convert it into a bias current I1 proportional to the VBAT voltage through voltage-dividing resistors and buffer resistors.

[0045] Specifically, the falling edge compensation module receives the VBAT voltage, and is connected to the INP terminal of the operational amplifier OP2 through the voltage-dividing resistors R1 and R2. The voltage at the INP terminal is , using the principle of virtual short of the operational amplifier, the voltage Similarly applied to resistor R3, MN1 and operational amplifier OP2, resistor R3 form a negative feedback loop, converting the voltage at the input terminal of the operational amplifier into the current flowing through R3, I = VINN / R3 = VINP / R3 = , and through the current leakage composed of MP1 and MP2, it is converted into a bias current I1 proportional to the VBAT voltage, and the corresponding current , let be a constant, that is, I1 = a*VBAT (Equation ①), which is linearly related to VBAT.

[0046] Figure 1-7 Figure 0000145 is an example diagram of the specific implementation of the rising edge compensation module. Its main function is to receive the reference voltage VREF and convert it into a fixed bias current I2.

[0047] Specifically, the rising edge compensation module receives the reference voltage VREF. Using the principle of virtual short of the operational amplifier, the voltage on resistor R4 is VREF. MN6 and operational amplifier OP1, resistor R4 form a negative feedback loop, converting the voltage at the input terminal of the operational amplifier into the current flowing through R4, I = VINN / R4 = VINP / R4 = VREF / R4, and through the current leakage composed of MP6 and MP7, it is input to the current mirror composed of MN7 and MN8, and converted into a fixed bias current I2, and the corresponding current (Equation ②), and R4 is a constant. Using a zero-temperature-drift resistor can generate a zero-temperature-drift bias current I2, which is beneficial to improving the rising edge compensation effect.

[0048] Figure 1-8 Figure 0000151 is an example diagram of the specific implementation of the slope control module. During the falling edge conversion of TXD, the slope control module receives the TXD signal and the bias current I1, and outputs a slope voltage VXTN proportional to VBAT; during the rising edge conversion of TXD, the slope control module receives the TXD signal and the bias current I2, and outputs a fixed slope voltage VXTN.

[0049] Specifically, the slope control module receives the output current I1 of the falling edge compensation module and the output current I2 of the rising edge compensation module. When the falling edge of TXD arrives, the upper transistor MP3 is turned on and the lower transistor MN2 is turned off. The slope control module receives the charging current I1 and charges the capacitor C2, and outputs a slope proportional to VBAT (Equation ③); when the rising edge of TXD arrives, the upper transistor MP3 is turned off and the lower transistor MN2 is turned on. The slope control module receives the discharging current I2 and discharges the capacitor C2, and outputs a fixed slope (Equation ④). By controlling the magnitudes of the currents I1 and I2, the slope of the VXTN voltage can be adjusted.

[0050] Figure 1-9: is an example diagram of a specific implementation of a voltage-controlled current module. The voltage-controlled current module receives the modulated slope voltage VXTN and converts it into a discharge current Idischarge. During the rising and falling edge conversion process, .

[0051] Specifically, the voltage-controlled current module receives the output voltage VXTN of the slope control module. Using the principle of virtual short of the operational amplifier, the voltage on the resistor R5 is VXTN. MN3, the operational amplifier OP3, and the resistor R5 form a negative feedback loop to convert the voltage at the input of the operational amplifier into a current flowing through R5, I=VINN / R5=VINP / R5=VXIN / R5, which is input to the current mirror composed of MN4 and MN5 through the current drain composed of MP4 and MP5, and converted into a slope current following VXTN. (Formula ⑤).

[0052] Depend on Figure 1-4 As shown, LIN communication falling edge time TF = (Since the discharge current Idischarge is much larger than the pull-up current of VBAT through the resistor R2, the pull-up current of VBAT through the resistor R2 is ignored).

[0053] Combining equations ①, ③ and ⑤, we can get TF= (Formula ⑥), TF has nothing to do with VBAT parameters.

[0054] The LIN communication rising edge time TR consists of two parts: one part is determined by the charging time constant R2C1 composed of VBAT through resistor R2 and capacitor C1, and the other part is determined by the discharge current Idischarge generated when the TXD rising edge arrives.

[0055] Combining equations ②, ④, and ⑤, we can know from Thevenin's theorem that the LIN communication rising edge time TR = (Formula 7); From the formula, it can be found that the compensation amount of LIN communication rising edge time TR is Related to VBAT, it is to offset the deviation caused by the conduction voltage drop and current limiting of diode D2 in the LIN port network.

[0056] Therefore, during LIN communication, the rise time TR is guaranteed to be equal to the fall time TF, and the duty cycle is implemented to meet the LIN communication consistency requirements. The EMI requirements can be met by adjusting the values ​​of the rise time TR and the fall time TF.

[0057] Figure 1-10 This is the simulation waveform of the LIN communication duty cycle. It can be seen from the figure that the falling edge time of the LIN node voltage does not change with the VBAT voltage, and the falling edge time and rising edge time are basically the same, ensuring that the duty cycle meets the LIN communication consistency requirements.

[0058] Figure 1-11 The simulation circuit is built according to the IEC 62228 protocol specification. The signal VEMI is the EMI simulation waveform of the LIN node, and the EMI limiting curves CLASSI, CLASSII, and CLASSIII of the LIN communication bus filter are imported. It can be seen from the figure that the high-frequency components of the LIN node EMI waveform signal VEMI are all less than the EMI limiting curves in the protocol specification, indicating that the EMI test of the embodiment of the present invention can pass the highest level of Class III.

[0059] Based on the same inventive concept as the above embodiment, the embodiment of the present invention further provides a LIN communication interface chip configured with the control circuit for optimizing electromagnetic interference and duty cycle.

[0060] Based on the same inventive concept as the above embodiment, the embodiment of the present invention further provides a LIN communication system, including a LIN port network and a LIN transmission channel module connected to the LIN port network. The LIN transmission channel module is implemented by using the control circuit for optimizing electromagnetic interference and duty cycle.

[0061] Based on the same inventive concept as the above embodiment, the embodiment of the present invention further provides a control method for optimizing electromagnetic interference and duty cycle, which is implemented by using the control circuit described in the foregoing embodiment. The control circuit is composed of a slope control module, a rising edge compensation module, a falling edge compensation module, and a voltage-controlled current module. The control method for optimizing electromagnetic interference and duty cycle based on this control circuit specifically includes: In the LIN node transition falling time TF stage, through the rising edge compensation module, the VBAT voltage is received and converted into a bias current I1 proportional to the VBAT voltage. The slope control module receives the TXD signal and the bias current I1 and outputs a slope voltage VXTN proportional to VBAT. The voltage-controlled current module receives the modulated slope voltage VXTN and converts it into a discharge current Idischarge proportional to VBAT, thereby compensating and offsetting the influence of the VBAT variable on the LIN transition falling time TF, that is, the falling time TF is fixed under different VBATs; In the LIN node transition rising time TR stage, a zero-temperature-drift bias current I2 is generated through the rising edge compensation module. The slope control module receives the TXD signal and the bias current I2 and outputs a fixed slope voltage VXTN. The voltage-controlled current module receives the modulated slope voltage VXTN and converts it into a fixed discharge current Idischarge, which is equivalent to increasing the LIN transition rising time TR so that TR = TF, and the duty cycle meets the LIN communication consistency requirements.

[0062] In the embodiments of the present invention, the values of the rise time TR and the fall time TF are adjusted to meet the EMI requirements.

[0063] In summary of the above embodiments, the core idea of the present invention is to compensate and offset the influence of the change of VBAT on EMI and duty cycle, adjust the rise time and the fall time, ensure that the rise time and the fall time are consistent, so that EMI can reach class Ⅲ and the duty cycle meets the consistency requirements of LIN communication.

[0064] The terms "including" and "having" in the description, claims and above drawings of the present invention, as well as any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A control circuit for optimizing electromagnetic interference and duty cycle, characterized in that: It includes a slope control module, a rising edge compensation module, a falling edge compensation module and a voltage-controlled current module; During the falling time phase of the LIN node conversion, the battery voltage is received through the falling edge compensation module and converted into a bias current I1 proportional to the battery voltage. The communication signal and the bias current I1 are received through the slope control module, and a slope voltage proportional to the battery voltage is output. The slope voltage is received through the voltage-controlled current module and converted into a discharge current proportional to the battery voltage, which is transmitted to the LIN port network. During the LIN node conversion rise time stage, the bias current I2 is generated by the rising edge compensation module, the communication signal and the bias current I2 are received by the slope control module, a fixed slope voltage is output, the slope voltage is received by the voltage-controlled current module, and converted into a fixed discharge current, which is transmitted to the LIN port network.

2. A control circuit for optimizing electromagnetic interference and duty cycle according to claim 1, characterized in that: The rising edge compensation module is connected to a reference voltage through a first operational amplifier, and applies the reference voltage to a first resistor using the operational amplifier virtual short principle, thereby forming a current which is input into a first current mirror through a first current drain and converted into a fixed bias current I2.

3. A control circuit for optimizing electromagnetic interference and duty cycle according to claim 2, characterized in that: The first resistor is a zero temperature drift resistor.

4. A control circuit for optimizing electromagnetic interference and duty cycle according to claim 1, characterized in that: The falling edge compensation module receives the battery voltage, divides the battery voltage through a voltage-dividing resistor and inputs the voltage into the second operational amplifier, applies the battery voltage to the second resistor by using the virtual short principle of the operational amplifier, forms a current and passes through the second current drain to be converted into a bias current I1 proportional to the battery voltage.

5. A control circuit for optimizing electromagnetic interference and duty cycle according to claim 1, characterized in that: The slope control module includes an upper power tube, a lower power tube and a capacitor, wherein the gates of the upper power tube and the lower power tube are respectively connected to the communication signal, the drains are commonly connected to the capacitor and the voltage-controlled current module, and the other end of the capacitor is grounded; the source of the upper power tube is connected to the bias current I1, and the source of the lower power tube is connected to the bias current I2.

6. A control circuit for optimizing electromagnetic interference and duty cycle according to claim 1, characterized in that: The voltage-controlled current module is connected to the output voltage of the slope control module through the third operational amplifier, and the output voltage is applied to the third resistor using the virtual short principle of the operational amplifier to form a current and input it into the second current mirror through the third current drain, and converted into a discharge current that follows the output voltage.

7. A LIN communication interface chip, characterized in that: A control circuit for optimizing electromagnetic interference and working cycle as claimed in any one of claims 1 to 6 is provided.

8. A LIN communication system, characterized in that: It comprises a LIN port network and a LIN transmission channel module connected to the LIN port network, wherein the LIN transmission channel module is implemented by the control circuit for optimizing electromagnetic interference and working cycle according to any one of claims 1 to 6.

9. A control method for optimizing electromagnetic interference and duty cycle, characterized in that: include: In the LIN node conversion fall time stage, the battery voltage is received and converted into a bias current I1 proportional to the battery voltage, the communication signal and the bias current I1 are slope controlled and a slope voltage proportional to the battery voltage is output, the slope voltage is converted into a discharge current proportional to the battery voltage, and transmitted to the LIN port network; During the LIN node conversion rise time phase, a reference voltage is received and converted into a bias current I2, the communication signal and the bias current I2 are slope controlled and a fixed slope voltage is output, the slope voltage is converted into a fixed discharge current and transmitted to the LIN port network.

Images