Drive circuit and CAN transceiver

Abstract

The application discloses a driving circuit and a CAN transceiver, comprising: a biasing module, a high-side driving module and a low-side driving module; the biasing module is configured to output a first biasing voltage through a first biasing output end and output a second biasing voltage through a second biasing output end; the high-side driving module comprises a first switch tube and a second switch tube, and the high-side driving module is configured to control the first switch tube based on the first biasing voltage and control the second switch tube based on the second biasing voltage to output a first voltage at a first voltage output end; the low-side driving module comprises a third switch tube and a fourth switch tube, and the low-side driving module is configured to control the third switch tube based on the first biasing voltage and control the fourth switch tube based on the second biasing voltage to output a second voltage at a second voltage output end. The driving circuit of the application can reduce and stabilize the on-resistance of the switch tube, improve the on performance of the switch tube, and improve the anti-electromagnetic interference performance of the CAN transceiver.

Description

Technical Field

[0001] This application relates to the field of integrated circuit technology, and more particularly to a driver circuit and a CAN transceiver. Background Technology

[0002] Controller Area Network (CAN) is a highly efficient, real-time, and reliable communication protocol, and an important communication standard in modern electronic systems. CAN transceivers incorporate backflow protection circuitry to meet the positive and negative voltage tolerance requirements of CAN transceivers.

[0003] However, the reduction in the gate-source voltage of the switching transistor in the backflow prevention circuit will cause nonlinearity of the CAN transceiver output impedance, affecting the symmetry of the CAN transceiver output impedance and resulting in poor electromagnetic interference (EMI) performance. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by this application is how to improve the linearity of the output impedance of the CAN transceiver, so as to increase the consistency of the output impedance of the CAN transceiver, improve the symmetry of the output impedance, and thus improve the electromagnetic interference resistance of the CAN transceiver.

[0005] To address at least one of the aforementioned technical problems, this application discloses a driving circuit and a CAN transceiver.

[0006] According to one aspect of this application, a driving circuit is provided, comprising: a bias module including a first bias output terminal and a second bias output terminal, the bias module being configured to: output a first bias voltage through the first bias output terminal and output a second bias voltage through the second bias output terminal; a high-side driving module including a high-side connection terminal and a first voltage output terminal, and a first switch and a second switch sequentially connected between the high-side connection terminal and the first voltage output terminal, the high-side driving module being configured to: control the first switch based on the first bias voltage and control the second switch based on the second bias voltage to output a first voltage at the first voltage output terminal; and a low-side driving module including a low-side connection terminal and a second voltage output terminal, and a third switch and a fourth switch sequentially connected between the low-side connection terminal and the second voltage output terminal, the low-side driving module being configured to: control the third switch based on the first bias voltage and control the fourth switch based on the second bias voltage to output a second voltage at the second voltage output terminal.

[0007] According to one aspect of this application, a CAN transceiver is provided, comprising: a driving circuit as provided above, and a receiver connected to the driving circuit, the receiver being configured to receive a signal output by the driving circuit.

[0008] In this embodiment, an additional bias module is provided in the driving circuit to generate bias voltages of different levels. These different bias voltages improve the stability of the on-resistance of each switch in the high-side and low-side driving modules. The driving circuit in this embodiment increases the gate-source voltage of the switches in the high-side and low-side driving modules by generating bias voltages, thereby reducing and stabilizing the on-resistance of the switches, improving their conduction performance, and ultimately enhancing the symmetry of the CAN transceiver's output impedance and its electromagnetic interference immunity.

[0009] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0011] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0012] Figure 1 A schematic diagram of the structure of a driving circuit according to some embodiments of this application is provided; Figure 2 Circuit diagrams of driving circuits according to some embodiments of this application are provided; Figure 3 Circuit diagrams of driving circuits according to other embodiments of this application are provided; Figure 4 Circuit diagrams of driving circuits according to other embodiments of this application are provided. Detailed Implementation

[0013] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this application.

[0014] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data used in this way can be interchanged where appropriate so that implementations can be carried out in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or circuits is not necessarily limited to those steps or circuits explicitly listed, but may include other steps or circuits not explicitly listed or inherent to such processes, methods, products, or devices.

[0015] Figure 1 A schematic diagram of the driving circuit provided according to some embodiments of this application is given. For example... Figure 1 As shown, the driving circuit includes a bias module 100, a high-side driving module 200, and a low-side driving module 300. The bias module 100 includes a first bias output terminal and a second bias output terminal. The bias module 100 is configured to output a first bias voltage through the first bias output terminal and a second bias voltage through the second bias output terminal.

[0016] The high-side drive module 200 includes a high-side connection terminal and a first voltage output terminal, the high-side connection terminal being configured to be connected to the power supply terminal Vdd. The high-side drive module 200 also includes a first switching transistor HV1 and a second switching transistor HV2 connected sequentially between the high-side connection terminal and the first voltage output terminal; that is, one end of the first switching transistor HV1 is connected to the high-side connection terminal, and the other end is connected to one end of the second switching transistor HV2, and the other end of the second switching transistor HV2 is connected to the first voltage output terminal. The high-side drive module 200 is connected to both the first bias output terminal and the second bias output terminal of the bias module 100, respectively receiving the first bias voltage output from the first bias output terminal and the second bias voltage output from the second bias output terminal; wherein, the first switching transistor HV1 is connected to the first bias voltage, and the second switching transistor HV2 is connected to the second bias voltage. The high-side drive module 200 controls the turn-on and turn-off of the first switch HV1 based on the first bias voltage, and controls the turn-on and turn-off of the second switch HV2 based on the second bias voltage, so as to output the first voltage CANH at the first voltage output terminal.

[0017] The low-side drive module 300 includes a low-side connection terminal and a second voltage output terminal, with the low-side connection terminal configured to be connected to ground (GND). The low-side drive module 300 also includes a third switch HV3 and a fourth switch HV4 connected sequentially between the low-side connection terminal and the second voltage output terminal; that is, one end of the third switch HV3 is connected to the low-side connection terminal, and the other end is connected to one end of the fourth switch HV4, while the other end of the fourth switch HV4 is connected to the second voltage output terminal. The low-side drive module 300 is connected to both the first bias output terminal and the second bias output terminal of the bias module 100, respectively receiving the first bias voltage output from the first bias output terminal and the second bias voltage output from the second bias output terminal; wherein, the third switch HV3 is connected to the first bias voltage, and the fourth switch HV4 is connected to the second bias voltage. The low-side drive module 300 controls the turn-on and turn-off of the third switch HV3 based on the first bias voltage, and controls the turn-on and turn-off of the fourth switch HV4 based on the second bias voltage, so as to output the second voltage CANL at the second voltage output terminal.

[0018] The switching transistors in the high-side drive module 200 and the low-side drive module 300 include N-type MOSFETs and P-type MOSFETs, respectively, to protect against positive and negative high voltages on the bus. In this embodiment, the bias module 100 outputs bias voltages to the switching transistors in the high-side drive module 200 and the low-side drive module 300 to improve their conduction performance. Since the switching transistors in the high-side drive module 200 and the low-side drive module 300 are of different types, the bias module 100 outputs two different bias voltages through different bias output terminals to control the conduction of different types of switching transistors. The bias output terminal of the bias module 100 is connected to the gate of the switching transistor to increase the gate-source voltage of the switching transistor through the bias voltage, reducing the on-resistance of the switching transistor and thus giving it better conduction characteristics. For example, the first bias voltage is an increased bias voltage, and the second bias voltage is a decreased bias voltage. Connecting the first bias voltage to an N-type switch improves the conduction performance of the N-type switch; connecting the second bias voltage to a P-type switch improves the conduction performance of the P-type switch. This embodiment of the application can improve the linearity of the CAN transceiver's output impedance, improve the impedance matching between the first and second voltage output terminals, and improve the symmetry of the output impedance while reducing the on-resistance of the switch. By improving the linearity and symmetry of the CAN transceiver's output impedance, this embodiment of the application can also reduce output signal distortion, reduce common-mode noise caused by output asymmetry, and improve the CAN transceiver's electromagnetic interference immunity.

[0019] In some embodiments, the first switch HV1, the second switch HV2, the third switch HV3, and the fourth switch HV4 are all high-voltage transistors, namely laterally diffused metal-oxide-semiconductor (LDMOS). High-voltage transistors have the characteristics of high voltage withstand and low on-resistance, making them particularly suitable for automotive electronics fields such as automotive systems.

[0020] In this embodiment, an additional bias module is provided in the driving circuit to generate bias voltages of different levels. This allows for the improvement of the stability of the on-resistance of the switching transistors in the high-side and low-side driving modules based on these different bias voltages. The driving circuit in this embodiment can increase the gate-source voltage of the switching transistors in the high-side and low-side driving modules according to the bias voltage generated by the bias module. With the increased gate-source voltage, the sensitivity of the switching transistor's on-resistance to changes in source-drain voltage, port voltage, and threshold voltage decreases. This reduces the degree to which the equivalent impedance of the CAN transceiver output changes with the output voltage, thereby improving the linearity of the output impedance, reducing and stabilizing the on-resistance of the switching transistor, and improving the switching transistor's conduction performance. This, in turn, improves the symmetry of the CAN transceiver's output impedance and enhances its electromagnetic interference immunity.

[0021] In some embodiments, please continue reading Figure 1 The driving circuit further includes a first switch module 410 and a second switch module 420. In one embodiment, the first switch module 410 includes a first switch S1, one end of which is connected to the high-side connection terminal of the high-side driving module 200, and the other end is connected to the power supply terminal Vdd. In one embodiment, the second switch module 420 includes a second switch S2, one end of which is connected to the low-side connection terminal of the low-side driving module 300, and the other end is connected to the ground terminal GND.

[0022] The first switch module 410 and the second switch module 420 are dominant / recessive switches for the CAN bus. When the first voltage CANH output from the first output terminal and the second voltage CANL output from the second output terminal are dominant, the first switch module 410 and the second switch module 420 are closed, and data interaction occurs between the CAN bus and the controller. When the first voltage CANH and the second voltage CANL are recessive, the first switch module 410 and the second switch module 420 are open, and data interaction between the CAN bus and the controller ends.

[0023] In some embodiments, please refer to Figure 2 , Figure 2 A circuit diagram of a driving circuit according to an embodiment of this application is provided. Figure 2As shown, the bias module 100 includes a first charge pump 110 and a second charge pump 120. The first charge pump 110 is connected to the high-side drive module 200, and the second charge pump 120 is connected to the low-side drive module 300. The high-side drive module 200 includes a first switch MN2 and a second switch MP2 connected between the high-side connection terminal CH_LV and the first voltage output terminal CANL. The first switch MN2 is an LDNMOS transistor, and the second switch MP2 is an LDPMOS transistor. The low-side drive module 300 includes a third switch MN1 and a fourth switch MP1 connected between the low-side connection terminal CL_LV and the second voltage output terminal CANL. The third switch MN1 is an LDNMOS transistor, and the fourth switch MP1 is an LDPMOS transistor.

[0024] like Figure 2 As shown, the first bias output terminal of the bias module 100 includes the first output terminal of the first charge pump 110 and the first output terminal of the second charge pump 120. The second bias output terminal of the bias module 100 includes the second output terminal of the first charge pump 110 and the second output terminal of the second charge pump. The input terminal of the first charge pump 110 is connected to the high-side connection terminal CH_LV, the first output terminal VG_NLDH1 of the first charge pump 110 is connected to the gate of the first switch MN2, and the second output terminal VG_PLDH1 of the first charge pump 110 is connected to the gate of the second switch MP2. The input terminal of the second charge pump 120 is connected to the low-side connection terminal CL_LV, the first output terminal VG_NLDL1 of the second charge pump 120 is connected to the third switch MN1, and the second output terminal VG_PLDL1 of the second charge pump 120 is connected to the fourth switch MP1.

[0025] The bias module 100 in this embodiment outputs a first bias voltage and a second bias voltage through two charge pumps. The first bias voltage and the second bias voltage are different and are respectively connected to different types of switching transistors to bias different types of switching transistors, thereby controlling the gate-source voltage of the corresponding switching transistors. It can be understood that the first bias voltages connected to the high-side drive module 200 and the low-side drive module 300 can be the same or different; that is, the voltage output from the first output terminal of the first charge pump 110 and the voltage output from the first output terminal of the second charge pump 120 can be the same or different. Similarly, the second bias voltages connected to the high-side drive module 200 and the low-side drive module 300 can be the same or different; that is, the voltage output from the second output terminal of the first charge pump 110 and the voltage output from the second output terminal of the second charge pump 120 can be the same or different. In this embodiment, it is sufficient to ensure that the first bias voltage and the second bias voltage within the same drive module are different.

[0026] In some embodiments, the first bias voltage includes a first sub-bias voltage and a second sub-bias voltage, and the second bias voltage includes a third sub-bias voltage and a fourth sub-bias voltage. The high-side connection terminal CH_LV is connected to the high-side signal VIN1, and the low-side connection terminal CL_LV is connected to the low-side signal VIN2.

[0027] Please continue reading. Figure 2 The first charge pump 110 is further configured to: increase the high-side signal VIN1 by a first preset value to obtain a first sub-bias voltage, and transmit the first sub-bias voltage to the first switch MN2. The first charge pump 110 also decreases the high-side signal VIN1 by a first preset value to obtain a third sub-bias voltage, and transmits the third sub-bias voltage to the second switch MP2. In one embodiment, the first preset value is 5V, the first sub-bias voltage is VIN1+5V, and the third sub-bias voltage is VIN1-5V.

[0028] For example, in the dominant state, the first switch module 410 and the second switch module 420 are closed. At this time, the high-side connection terminal CH_LV is raised from 2.5V to near the power supply voltage of 5V. Simultaneously, the first sub-bias voltage VG_NLDH1 output from the first output terminal of the first charge pump 110 is raised to approximately 10V (5V+5V), and the third sub-bias voltage VG_PLDH1 output from the second output terminal of the first charge pump 110 is reduced to approximately 0V (5V-5V). The first charge pump 110 increases the gate-source voltage Vgs of the switching transistor in the high-side drive module 200 by increasing the output bias voltage. The larger gate-source voltage reduces the on-resistance of the switching transistor, thereby preventing the body diode in the switching transistor from turning on. It also reduces the sensitivity to the threshold voltage, improving the switching performance and electromagnetic interference performance of the switching transistor.

[0029] Please continue reading. Figure 2 The second charge pump 120 is further configured to: increase the low-side signal VIN2 by a second preset value to obtain a second sub-bias voltage, and transmit the second sub-bias voltage to the third switch MN1. The second charge pump 120 also decreases the low-side signal VIN2 by a second preset value to obtain a fourth sub-bias voltage, and transmits the fourth sub-bias voltage to the fourth switch MP1. In one embodiment, the second preset value is 5V, the second sub-bias voltage is VIN2+5V, and the fourth sub-bias voltage is VIN2-5V.

[0030] For example, in the dominant state, the first switch module 410 and the second switch module 420 are closed. At this time, the low-side connection terminal CL_LV drops from 2.5V to the same level as the ground terminal, close to 0V. Simultaneously, the second sub-bias voltage VG_NLDL1 output from the first output terminal of the second charge pump 120 is raised to approximately 5V (0V+5V), and the fourth sub-bias voltage VG_PLDL1 output from the second output terminal of the second charge pump 120 is reduced to approximately -5V (0V-5V). The second charge pump 120 increases the gate-source voltage Vgs of the switching transistor in the low-side drive module 300 by outputting the bias voltage. The larger gate-source voltage reduces the on-resistance of the switching transistor, thereby preventing the body diode in the switching transistor from turning on. It also reduces the sensitivity to the threshold voltage, improving the switching performance and electromagnetic interference performance of the switching transistor.

[0031] In some embodiments, please continue reading Figure 2 The bias module 100 further includes a first feedback unit 130, the input terminal of which is connected to the first voltage output terminal of the high-side drive module 200, and the output terminal of which is connected to the control terminal CTRL1 of the first charge pump 110. The first feedback unit 130 is configured to control the operating state of the first charge pump 110 according to the first voltage CANH.

[0032] In this embodiment, the gate-source voltage of the switching transistor in the high-side drive module 200 is controlled by the first charge pump 110. However, when the CANH output from the first voltage output terminal of the high-side drive module 200 is a positive high voltage, the high voltage will be transmitted to the drain of the first switching transistor MN2 through the second switching transistor MP2. Since the gate-source voltage of the first switching transistor MN2 is approximately 5V, the voltage at the drain will be transmitted to the high-side connection terminal CH_LV, raising the high-side signal at the high-side connection terminal. Since the input terminal of the first charge pump 110 is connected to the high-side signal at the high-side connection terminal, if the high-side signal is raised, it will affect the bias voltage output by the first charge pump 110, ultimately leading to a large current path between the first output terminal and the high-side connection terminal, which does not meet the backflow prevention requirement. A similar problem may also exist when the first output terminal is negative. Therefore, in this embodiment, the first feedback unit 130 detects the CANH output from the first voltage output terminal and determines the operating state of the first charge pump 110 based on the CANH output from the first voltage output terminal.

[0033] In some embodiments, the first feedback unit 130 is further configured to disable the first charge pump 110 when the first voltage CANH is greater than a first threshold or less than a second threshold.

[0034] The first voltage CANH being greater than the first threshold can occur when the high-side drive module 200 outputs a positive high voltage that exceeds the first threshold, affecting the operation of the CAN transceiver. In this case, the first feedback unit 130 outputs a control enable signal to the control terminal CTRL1 of the first charge pump 110, disabling the first charge pump 110 from operation. The first voltage CANH being less than the second threshold can occur when the high-side drive module 200 outputs a negative high voltage that is less than the second threshold, affecting the operation of the CAN transceiver. In this case, a control enable signal is also output to the control terminal CTRL1 of the first charge pump 110, disabling the first charge pump 110 from operation.

[0035] In some embodiments, please continue reading Figure 2 The bias module 100 further includes a second feedback unit 140. The input terminal of the second feedback unit 140 is connected to the second voltage output terminal of the low-side drive module 300, and the output terminal of the second feedback unit 140 is connected to the control terminal CTRL2 of the second charge pump 120. The second feedback unit 140 is configured to control the operating state of the second charge pump 120 according to the second voltage CANL.

[0036] In this embodiment, the gate-source voltage of the switching transistor in the low-side drive module 300 is controlled by the second charge pump 120. Similar to the high-side drive module 200, when the CANL output from the second output terminal of the low-side drive module 300 is high voltage (including positive and negative high voltage), it will affect the low-side signal at the low-side connection terminal, thereby affecting the operating state of the second charge pump 120, which does not meet the backflow prevention requirement of the low-side drive module 300. Therefore, in this embodiment, the second feedback unit 140 detects the CANL output from the second voltage output terminal and determines the operating state of the second charge pump 120 based on the CANL output from the second voltage output terminal.

[0037] In some embodiments, the second feedback unit 140 is further configured to disable the second charge pump 120 when the second voltage CANL is greater than a third threshold or less than a fourth threshold.

[0038] The second voltage CANL being greater than the third threshold can occur when the positive high voltage output from the second voltage output terminal of the low-side drive module 300 exceeds the third threshold, affecting the operation of the CAN transceiver. In this case, the second feedback unit 140 outputs a control enable signal to the control terminal CTRL2 of the second charge pump 120, disabling the second charge pump 120 from operation. The second voltage CANL being less than the fourth threshold can occur when the negative high voltage output from the second voltage output terminal of the low-side drive module 300 is less than the fourth threshold, affecting the operation of the CAN transceiver. In this case, a control enable signal is also output to the control terminal CTRL2 of the second charge pump 120, disabling the second charge pump 120 from operation.

[0039] It is understood that the first and third thresholds can be the same or different, and the second and fourth thresholds can be the same or different. This application embodiment does not impose any restrictions on this; in practical applications, thresholds can be defined according to specific needs.

[0040] In some embodiments, please refer to Figure 3 , Figure 3 A circuit diagram of a driving circuit according to another embodiment of this application is provided. Figure 3 As shown, the first feedback unit 130 and the second feedback unit 140 are combined into one feedback unit. This feedback unit includes two input terminals and two output terminals. The two input terminals of the feedback unit are respectively connected to the first voltage output terminal of the high-side drive module 200 and the second voltage output terminal of the low-side drive module 300. The two output terminals of the feedback unit are respectively connected to the control terminal CTRL1 of the first charge pump 110 and the control terminal CTRL2 of the second charge pump 120.

[0041] In this embodiment, two floating charge pumps, a first charge pump 110 and a second charge pump 120, are provided in the bias module 100. These pumps obtain bias voltages based on the high-side signal received at the high-side connection terminal and the low-side signal received at the low-side connection terminal, respectively. This raises the gate-source voltage of the switching transistors in the high-side drive module 200 and the low-side drive module 300, improving the linearity and symmetry of the CAN transceiver's output impedance and enhancing its electromagnetic interference immunity. Furthermore, by controlling the operating states of the first and second charge pumps, this embodiment can increase the absolute value of the gate-source voltage of the switching transistors while reducing the risk of high voltage backflow from the bus into the chip.

[0042] In some embodiments, please refer to Figure 4 , Figure 4 A circuit diagram of a driving circuit according to another embodiment of this application is provided. Figure 4 As shown, the bias module 100 includes a third charge pump 150, and the first output terminal of the third charge pump 150 is connected to the first switch MN2 and the third switch MN1, respectively. The first output terminal of the third charge pump 150 is the first bias output terminal of the bias module 100.

[0043] In this embodiment, a third charge pump 150 is provided in the bias module 100. The first bias voltage and the second bias voltage are output simultaneously through the charge pump, and the first bias voltage is sent to the first switch MN2 of the high-side drive module 200 and the third switch MN1 of the low-side drive module 300, respectively.

[0044] In some embodiments, please continue reading Figure 4The driving circuit further includes a first switch module 410 and a second switch module 420. In one embodiment, the first switch module 410 includes a first switch S1, one end of which is connected to the high-side connection terminal of the high-side driving module 200, and the other end is connected to the power supply terminal Vdd. In one embodiment, the second switch module 420 includes a second switch S2, one end of which is connected to the low-side connection terminal of the low-side driving module 300, and the other end is connected to the ground terminal GND.

[0045] The first switch module 410 and the second switch module 420 are dominant / recessive switches for the CAN bus. When the first voltage CANH output from the first output terminal and the second voltage CANL output from the second output terminal are dominant, the first switch module 410 and the second switch module 420 are closed, and data interaction occurs between the CAN bus and the controller. When the first voltage CANH and the second voltage CANL are recessive, the first switch module 410 and the second switch module 420 are open, and data interaction between the CAN bus and the controller ends.

[0046] In some embodiments, the bias module 100 further includes a first resistor R1 and a third resistor R3. The first output terminal of the third charge pump 150 is connected to the gate of the first switching transistor MN2 via the first resistor R1, and to the gate of the third switching transistor MN1 via the third resistor R3, to output a first bias voltage to the gates of the first switching transistor MN2 and the third switching transistor MN1, respectively. In some embodiments, the third charge pump 150 is further configured to increase the power supply voltage VCC by a third preset value to obtain the first bias voltage. In one embodiment, the third preset value is 0.7V.

[0047] In some embodiments, please continue reading Figure 4 The second output terminal of the third charge pump 150 is connected to the second switch MP2 and the fourth switch MP1, respectively. The second output terminal of the third charge pump 150 is also the second bias output terminal of the bias module 100.

[0048] In this embodiment, the second bias voltage output from the second output terminal of the third charge pump 150 is sent to the second switch MP2 of the high-side drive module 200 and the fourth switch MP1 of the low-side drive module 300, respectively.

[0049] In some embodiments, the bias module 100 further includes a second resistor R2 and a fourth resistor R4. The second output terminal of the third charge pump 150 is connected to the gate of the second switch MP2 via the second resistor R2 and to the gate of the fourth switch MP1 via the fourth resistor R4, to output a second bias voltage to the gates of the second switch MP2 and the fourth switch MP1, respectively. In some embodiments, the third charge pump 150 is further configured to reduce the ground terminal voltage GND by a third preset value to obtain the second bias voltage. In one embodiment, the third preset value is 0.7V.

[0050] The driving circuit of this application embodiment can change the performance of the CAN transceiver by using only a third charge pump 150. When the bus outputs positive or negative high voltage, the gate bias of the switching transistor does not rise or fall with the positive feedback of the output voltage at the voltage output terminal. The switching transistor can remain off or limit the internal node from being pulled, thereby reducing the risk of the high voltage of the bus being transmitted to the inside of the chip and achieving the anti-backflow effect.

[0051] This application's embodiments not only reduce the cost of the driver circuit but also reduce low-frequency electromagnetic interference (EMI) of the CAN transceiver. Typically, the first voltage output terminal CANH and the second voltage output terminal CANL of the CAN transceiver are connected via a 60Ω terminating resistor. In recessive mode, both the first voltage output terminal CANH and the second voltage output terminal CANL are 2.5V. When switching from recessive to dominant mode, the first voltage output terminal CANH rises to above 2.5V, while the second voltage output terminal CANL drops to below 2.5V. When switching from dominant to recessive mode again, the first voltage output terminal CANH and the second voltage output terminal CANL move from a high position (above 2.5V) and a low position (below 2.5V) respectively towards 2.5V; that is, the directions of change for the first voltage output terminal CANH and the second voltage output terminal CANL are opposite. If the LDMOS gates of the first voltage output terminal CANH and the second voltage output terminal CANL are biased separately, the output of the charge pump will be coupled by the bus differential voltage change during the dominant-recessive switching process, causing EMI problems. This requires a large decoupling capacitor, and the recovery time is also relatively slow. In this embodiment, a third charge pump 150 is provided in the bias module 100. The high-side drive module 200 and the low-side drive module 300 share the bias voltage output by the third charge pump 150, so that the coupled charge generated by the opposite direction change is partially neutralized, reducing the amount of charge that the third charge pump 150 needs to replenish. This can optimize the electromagnetic interference resistance performance and improve the recovery speed with a smaller decoupling capacitor.

[0052] Secondly, embodiments of this application also provide a CAN transceiver, including: a driving circuit as provided in the above embodiments, and a receiver connected to the driving circuit, the receiver being configured to receive signals output by the driving circuit.

[0053] The signals output by the driver circuit include a first voltage and a second differential voltage signal. When the CAN transceiver is in a dominant state, the driver circuit controls the first voltage CANH output terminal to increase and the second voltage CANL output terminal to decrease, thereby forming a dominant differential voltage between the first and second voltage output terminals. When the CAN transceiver is in a recessive state, the driver circuit controls the first and second voltage output terminals to return to approximately the same recessive level. The receiver can determine the current bus state by detecting the differential voltage between the first and second voltage output terminals and output the corresponding received data.

[0054] It should be understood that for a detailed description of the structure, operation, and beneficial effects of the above-mentioned CAN transceiver, please refer to the embodiment of the above-mentioned drive circuit, which will not be repeated here.

[0055] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. In the above embodiments, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to the relevant descriptions of other embodiments.

[0056] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0057] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent variations, or alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the market of the various embodiments, or to enable other persons skilled in the art to understand the various embodiments disclosed herein.

Claims

1. A driving circuit, characterized in that, include: The bias module includes a first bias output terminal and a second bias output terminal. The bias module is configured to output a first bias voltage through the first bias output terminal and output a second bias voltage through the second bias output terminal. A high-side drive module includes a high-side connection terminal and a first voltage output terminal, and a first switch and a second switch connected in sequence between the high-side connection terminal and the first voltage output terminal. The high-side drive module is configured to: control the first switch based on the first bias voltage and control the second switch based on the second bias voltage to output a first voltage at the first voltage output terminal. A low-side drive module includes a low-side connection terminal and a second voltage output terminal, and a third switch and a fourth switch connected in sequence between the low-side connection terminal and the second voltage output terminal. The low-side drive module is configured to control the third switch based on a first bias voltage and control the fourth switch based on a second bias voltage to output a second voltage at the second voltage output terminal.

2. The driving circuit according to claim 1, characterized in that, Also includes: The first switch module has one end connected to the high-side connection terminal of the high-side drive module and the other end connected to the power supply terminal. The second switch module has one end connected to the low-side connection terminal of the low-side drive module and the other end connected to the ground terminal.

3. The driving circuit according to claim 1, characterized in that, The bias module includes a first charge pump connected to the high-side drive module and a second charge pump connected to the low-side drive module; wherein, The input terminal of the first charge pump is connected to the high-side connection terminal, the first output terminal of the first charge pump is connected to the first switching transistor, and the second output terminal of the first charge pump is connected to the second switching transistor. The input terminal of the second charge pump is connected to the low-side connection terminal, the first output terminal of the second charge pump is connected to the third switch, and the second output terminal of the second charge pump is connected to the fourth switch. The first bias output terminal of the bias module includes the first output terminal of the first charge pump and the first output terminal of the second charge pump, and the second bias output terminal of the bias module includes the second output terminal of the first charge pump and the second output terminal of the second charge pump.

4. The driving circuit according to claim 3, characterized in that, The first bias voltage includes a first sub-bias voltage and a second sub-bias voltage, and the second bias voltage includes a third sub-bias voltage and a fourth sub-bias voltage; the high-side connection terminal is connected to a high-side signal, and the low-side connection terminal is connected to a low-side signal; wherein, The first charge pump is further configured to: increase the high-side signal by a first preset value to obtain a first sub-bias voltage, and transmit the first sub-bias voltage to the first switching transistor; decrease the high-side signal by the first preset value to obtain a third sub-bias voltage, and transmit the third sub-bias voltage to the second switching transistor; The second charge pump is further configured to: increase the low-side signal by a second preset value to obtain the second sub-bias voltage, and transmit the second sub-bias voltage to the third switch; decrease the low-side signal by the second preset value to obtain the fourth sub-bias voltage, and transmit the fourth sub-bias voltage to the fourth switch.

5. The driving circuit according to claim 3, characterized in that, Also includes: A first feedback unit is configured to control the operating state of the first charge pump based on the first voltage, with its input terminal connected to the first voltage output terminal of the high-side drive module and its output terminal connected to the control terminal of the first charge pump. The second feedback unit has its input terminal connected to the second voltage output terminal of the low-side drive module and its output terminal connected to the control terminal of the second charge pump. The second feedback unit is configured to control the operating state of the second charge pump according to the second voltage.

6. The driving circuit according to claim 5, characterized in that, The first feedback unit is further configured to disable the first charge pump when the first voltage is greater than a first threshold or less than a second threshold; the second feedback unit is further configured to disable the second charge pump when the second voltage is greater than a third threshold or less than a fourth threshold.

7. The driving circuit according to claim 1, characterized in that, The bias module includes a third charge pump, the first output terminal of which is connected to the first switch and the third switch respectively, and the second output terminal of which is connected to the second switch and the fourth switch respectively. Wherein, the first bias output terminal of the bias module is the first output terminal of the third charge pump, and the second bias output terminal of the bias module is the second output terminal of the third charge pump.

8. The driving circuit according to claim 7, characterized in that, It also includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first output terminal of the third charge pump is connected to the first switching transistor through the first resistor and to the third switching transistor through the third resistor; the second output terminal of the third charge pump is connected to the second switching transistor through the second resistor and to the fourth switching transistor through the fourth resistor.

9. The driving circuit according to claim 7, characterized in that, Also includes: The first switch module has one end connected to the high-side connection terminal of the high-side drive module and the other end connected to the power supply terminal. The second switch module has one end connected to the low-side connection terminal of the low-side drive module and the other end connected to the ground terminal.

10. The driving circuit according to claim 9, characterized in that, The third charge pump is further configured to: increase the power supply voltage by a third preset value to obtain the first bias voltage, and decrease the ground voltage by the third preset value to obtain the second bias voltage.

11. A CAN transceiver, characterized in that, include: The driving circuit as described in any one of claims 1 to 10, and the receiver connected to the driving circuit, wherein the receiver is configured to receive a signal output by the driving circuit.

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