Bus drive unit and control device

Abstract

The embodiment of the invention provides a bus driving unit and control equipment. The bus driving unit comprises an amplifier circuit, the first input end of the amplifier circuit is connected to a reference voltage, and the output end of the amplifier circuit is used for outputting a voltage control signal; the control end of the switching circuit is connected to the output end of the amplifier circuit, the switching circuit is used for being switched off when the voltage control signal is lower than a preset voltage threshold value, one end of the switching circuit is connected to the second input end of the amplifier circuit and is grounded through a resistor, and a negative feedback branch of the amplifier circuit is formed, the other end of the switching circuit is connected to a driving output end of a bus signal and a driving pull-up circuit; and the pull-down circuit is used for receiving the bus signal and pulling down the voltage control signal to be lower than the preset voltage threshold value when the level state of the bus signal is high level.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of electronic and electrical technology, and in particular to a bus driving unit and a control device. Background Art

[0002] At present, some serial communication buses use recessive and dominant levels to carry control information. For example, the CAN bus (Controller Area Network) is a flexible and efficient serial communication protocol that is widely used in the fields of automobiles, industrial control, medical equipment, etc. It uses differential signal transmission and realizes data communication through two lines (CAN_H and CAN_L). In the CAN bus, the concepts of dominant and recessive levels are the basis of its communication.

[0003] For another example, the LIN (Local Interconnect Network) bus is widely used in the automotive field due to its advantages such as low cost, only one bus, no need for crystal synchronization of slave nodes, and no need for a dedicated MCU controller. It is usually used as a supplement to the CAN bus, that is, LIN serves as a lower-layer network to assist the CAN bus in completing vehicle control, such as control of doors, windows, air conditioners, and lights.

[0004] In such a serial communication bus, it is expected that the bus signal can be reliably driven by a bus driver unit to achieve reliable recessive and dominant levels. However, current bus driver units have high requirements on the voltage resistance of the switch circuits used, which increases the difficulty of manufacturing the bus driver units. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a bus driving unit and a control device to solve the above problems.

[0006] According to a first aspect of an embodiment of the present invention, a bus driving unit is provided, comprising: an amplifier circuit, a first input terminal of the amplifier circuit being connected to a reference voltage, and an output terminal of the amplifier circuit being used to output a voltage control signal; a switch circuit, a control terminal of the switch circuit being connected to the output terminal of the amplifier circuit, and being used to shut down when the voltage control signal is lower than a preset voltage threshold, one terminal of the switch circuit being connected to a second input terminal of the amplifier circuit and being grounded through a resistor to form a negative feedback branch of the amplifier circuit, wherein the other terminal of the switch circuit is connected to a driving output terminal of a bus signal and a driving pull-up circuit; and a pull-down circuit, the pull-down circuit being used to receive the bus signal and to pull the voltage control signal down to a level lower than the preset voltage threshold when the level state of the bus signal is high.

[0007] In another implementation of the present invention, the amplifier circuit also includes a current mirror, multiple first current sources and a first resistor, the multiple driving branches of the current mirror are respectively grounded through the multiple first current sources, one end of the first resistor is grounded, and the other end of the first resistor is connected to the load branch of the current mirror and the first input terminal of the amplifier circuit for generating the reference voltage.

[0008] In another implementation of the present invention, the driving branch of the current mirror includes a plurality of MOS tubes cascaded between a first power supply voltage and one end of the first current source, the other end of the first current is grounded, and the gates of the plurality of first MOS tubes are connected to each other and to one end of the first current source.

[0009] In another implementation of the present invention, the switch circuit includes a first MOS transistor, which is an N-type MOS transistor, a source of which is connected to the second input terminal and grounded through a second resistor, a drain of which is connected to one end of the drive pull-up circuit, i.e., the drive output terminal, through a diode, the other end of the drive pull-up circuit is connected to a second power supply voltage, and a gate of the first MOS transistor is connected to the output terminal of the amplifier circuit.

[0010] In another implementation of the present invention, the pull-down circuit is connected between the output end of the amplifier circuit and the ground, and the pull-down circuit is used to receive the bus signal and absorb the signal current at the output end of the amplifier when the level state of the bus signal is a high level to pull the voltage control signal down to below the preset voltage threshold.

[0011] In another implementation of the present invention, the pull-down circuit is further used to: turn off the pull-down function of the pull-down circuit when the level state of the bus signal is at a low level, and the output end of the amplifier pulls up the voltage control signal to be greater than the preset voltage threshold.

[0012] In another implementation of the present invention, the pull-down circuit includes a second MOS tube and a third MOS tube, the drain of the second MOS tube and the drain of the third MOS tube are connected to the output end of the amplifier circuit, the gate of the second MOS tube and the gate of the third MOS tube are used to receive the bus signal, the source of the second MOS tube is grounded through a second current source, and the source of the second MOS tube is grounded through a first capacitor.

[0013] In another implementation of the present invention, the amplifier circuit is a rail-to-rail amplifier, the first input end is a non-inverting input end of the rail-to-rail amplifier, and the second input end is an inverting input end of the rail-to-rail amplifier.

[0014] In another implementation of the present invention, the rail-to-rail amplifier includes: an input stage circuit and an output stage circuit, the input stage circuit includes a first differential circuit and a second differential circuit, wherein the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the first differential circuit, and the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the second differential circuit. When the voltage difference between the input signal at the input terminal and the first power supply voltage is greater than the voltage difference between the input signal and the ground, the output terminal of the first differential circuit is connected to the output stage circuit. When the voltage difference between the input signal and the first power supply voltage is less than the voltage difference between the input signal and the ground, the output terminal of the second differential circuit is connected to the output stage circuit.

[0015] According to a second aspect of an embodiment of the present invention, a control device is provided, comprising: the bus driving unit according to the first aspect; and a control unit connected to the bus driving unit and configured to output a bus signal.

[0016] In the scheme of the embodiment of the present invention, the pull-down circuit pulls down the voltage control signal to below the preset voltage threshold when the level state of the bus signal is high, and the switch circuit is turned off when the voltage control signal is lower than the preset voltage threshold, thereby disconnecting the connection between the driving pull-up circuit and the driving output end, so that the driving pull-up circuit can pull up the output voltage of the driving output end to obtain a high-level driving signal of the bus signal; the pull-down circuit is in a turned-off state when the level state of the bus signal is low, and has no pull-down function, and the amplifier output end pulls up the voltage control signal to the first power supply voltage (less than 5.5V), which is higher than the preset voltage threshold, and the switch circuit is turned on when the voltage control signal is higher than the preset voltage threshold, so that the output voltage of the output end is pulled down to obtain a low-level driving signal of the bus signal; that is, when the output bus signal outputs a high-level driving signal and a low-level driving signal, the voltage control signal of the switch circuit is less than 5.5V, which reduces the voltage resistance requirement of the switch circuit, and is conducive to realizing the production and manufacturing process such as the tape-out of the bus driving unit as a chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1A A schematic block diagram of a communication system of a LIN bus to which some examples of the present invention are applicable.

[0019] Figure 1B Schematic block diagram of a control device applicable to some examples of the present invention.

[0020] Figure 2 Schematic block diagrams of some exemplary bus driver units.

[0021] Figure 3 Schematic block diagrams of bus driver units according to some examples of the present invention.

[0022] Figure 4 for Figure 3 A schematic circuit diagram of a bus driver unit of an embodiment of the present invention.

[0023] Figure 5 for Figure 3 Schematic circuit diagrams of amplifier circuits of some examples of embodiments. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in the field based on the embodiments in the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0025] The specific implementation of the embodiment of the present invention is further described below in conjunction with the accompanying drawings of the embodiment of the present invention.

[0026] FIG. 1 shows a communication system of a LIN bus to which some examples of the present invention are applicable. Figure 1A The communication system 100 uses a LIN bus 30 for signal transmission. The LIN bus 30 is connected between a host 20 and at least one slave 10. Figure 1A In the example of FIG, an example of a host 20 communicating with N slaves is shown. LIN only needs one bus, the slave nodes do not need crystal synchronization, and do not need a dedicated MCU controller. It is widely used in the automotive field and is usually used as a supplement to the CAN bus. For example, control devices such as the braking device of the vehicle air conditioner, the window lifting device, and the vehicle atmosphere light can be used as slaves to accept the control of the main controller of the vehicle as the host, forming an electronic control system for the vehicle.

[0027] like Figure 1BAs shown, the control device 10 as a slave may be configured with an interconnected bus driver unit 110 and a control unit 120 such as an MCU controller. It should be understood that the LIN bus is spread throughout various parts of the vehicle and has a long total length. Therefore, during operation, when the bus signal of the control unit 120 switches between a dominant state and a recessive state, the bus driver unit 110 is required to drive the bus signal to obtain a reliable recessive level and a dominant level.

[0028] Generally speaking, when the bus driver unit has high requirements on the voltage resistance of the switch circuit used, the manufacturing difficulty of the bus driver unit increases. For example, the bus driver unit cannot be taped out as a chip.

[0029] For example, Figure 2 The bus driving unit shown includes: a current mirror unit 101, a logic control unit 102, an operational amplifier unit 103 and a driving unit 104. The current mirror unit 101 is used to provide current input to the operational amplifier unit 103. The logic control unit 102 is used to control whether the current mirror unit 101 outputs current to the operational amplifier unit 103 according to an enable signal of a first input port and to control the current mirror unit 101 to output currents of different sizes to the operational amplifier unit 103 according to a configuration signal of a second input port. The operational amplifier unit 103 is used to achieve proportional amplification of current to drive the power transistor 104. The driving unit 104 is used to drive the external output load R3 of the LIN bus. Specifically, in the driving unit 10, the gate of the power transistor M4 is connected to the output end of the operational amplifier AMP, the drain of the power transistor M4 is connected to one end of the second resistor R2, and the source of the power transistor M4 is used as the output end of the LIN bus driving circuit to connect the output load R3.

[0030] It can be seen that when the power transistor M4 is turned off, the gate voltage of the power transistor M4 will be pulled down to a low level, and the gate-source voltage VGS will reach the voltage of the power supply terminal VBAT (6-18V). The withstand voltage of VGS in the general process is 5.5V and below 5.5V, and only a few processes can reach 6-18V. Therefore, using general processes, the VGS voltage of this architecture will usually significantly exceed the withstand voltage requirements of the power transistor M4. For this reason, various embodiments of the present invention provide a series of solutions that can reduce the withstand voltage requirements of the switch circuit, which is conducive to realizing the production and manufacturing process of the bus driver unit as a chip tape-out. Specifically, Figure 3 The bus driving unit 110 , which illustrates some examples of the present invention, includes an amplifier circuit 310 , a switch circuit 320 , and a pull-down circuit 330 .

[0031] Specifically, a first input terminal of the amplifier circuit 310 is connected to a reference voltage, and an output terminal of the amplifier circuit 310 is used to output a voltage control signal.

[0032] It should be understood that the amplifier circuit 310 can be an amplifier such as a rail-to-rail amplifier for non-distortion signal amplification within the signal range. The amplifier circuit 310 receives a reference voltage and generates a voltage control signal based on this input. The first input terminal of the amplifier circuit is directly connected to the reference voltage to ensure the accuracy of the signal. The output terminal is responsible for outputting the voltage control signal. The switch circuit 320 is connected to the second input terminal of the amplifier circuit 310 and is grounded through the second resistor to form a negative feedback branch, which helps to stabilize the output of the amplifier.

[0033] In addition, the control end of the switch circuit 320 is connected to the output end of the amplifier circuit, and is used to shut down when the voltage control signal is lower than the preset voltage threshold. One end of the switch circuit 320 is connected to the second input end of the amplifier circuit and grounded through a resistor to form a negative feedback branch of the amplifier circuit. The other end of the switch circuit 320 is connected to the driving output end of the bus signal and the driving pull-up circuit.

[0034] It should be understood that the switch circuit 320 responds to the voltage control signal generated by the amplifier circuit 310. The other end of the switch circuit 320 is connected to the driving output end of the bus signal and the driving pull-up circuit. When the voltage control signal is lower than the preset voltage threshold, the switch circuit 320 will be closed and cut off the connection with the driving pull-up circuit. When the voltage control signal is higher than the preset voltage threshold, the switch circuit 320 will be turned on and connected to the driving pull-up circuit. For example, the driving pull-up circuit can be an external pull-up circuit of the bus driving unit 110.

[0035] In addition, the pull-down circuit 330 is used to receive the bus signal, and pull the voltage control signal down to below the preset voltage threshold when the level state of the bus signal is high. For example, the pull-down circuit 330 can be implemented as a switch circuit, connected between the output end of the amplifier circuit 310 and the ground. The pull-down circuit 330 receives the bus signal, and when the bus signal is high, pulls the voltage control signal down to below the preset voltage threshold, that is, the pull-down circuit 330 can correctly respond to the change of the bus signal and reliably pull down the voltage control signal output by the amplifier circuit 310.

[0036] In the scheme of the embodiment of the present invention, the pull-down circuit pulls down the voltage control signal to below the preset voltage threshold when the level state of the bus signal is high, and the switch circuit is turned off when the voltage control signal is lower than the preset voltage threshold, thereby disconnecting the connection between the driving pull-up circuit and the driving output end, so that the driving pull-up circuit can pull up the output voltage of the driving output end to obtain a high-level driving signal of the bus signal; when the level state of the bus signal is low, the pull-down circuit itself is in a turned-off state and has no pull-down function, and the amplifier output end pulls up the voltage control signal to the first power supply voltage (less than 5.5V), which is higher than the preset voltage threshold, and the switch circuit is turned on when the voltage control signal is higher than the preset voltage threshold, so that the output voltage of the output end is pulled down to obtain a low-level driving signal of the bus signal. That is to say, when the output bus signal outputs a high-level driving signal and a low-level driving signal, the voltage control signal of the switch circuit is less than 5.5V, which reduces the voltage resistance requirements of the switch circuit, and is conducive to realizing the production and manufacturing processes such as the tape-out of the bus driving unit as a chip.

[0037] In some examples, the amplifier circuit further includes a current mirror, a plurality of first current sources and a first resistor. The plurality of driving branches of the current mirror are grounded through the plurality of first current sources respectively, one end of the first resistor is grounded, and the other end of the first resistor is connected to the load branch of the current mirror and the first input terminal of the amplifier circuit, for generating a reference voltage. That is, the current of the plurality of first current sources is copied to the load branch through the current mirror to obtain a stable current, and the stable current is used to obtain a stable reference voltage at the first input terminal of the amplifier circuit through the action of the first resistor.

[0038] Specifically, Figure 4 As shown, the multiple first current sources are current source I1 and current source I2, and the current mirror includes M1, M2, M3, M4 and M5 as N-type MOS tubes. Among them, the gates of M1, M2, M3, M4 and M5 can be connected to each other. In addition, M1 is set in a driving branch, M2 and M3 are set in another driving branch through cascade connection, and M4 and M5 are set in a load branch through cascade connection. The driving branch is connected between the first power supply voltage and the ground, and the load branch is connected between the first power supply voltage and the first input terminal of the amplifier circuit. For example, Figure 4 The non-inverting input of the amplifier.

[0039] In a driving branch, the source of M1 is connected to the power supply voltage VDD, the drain of M1 is connected to one end of the current source 1, and the other end of the current source 1 is grounded.

[0040] In another driving branch, the source of M2 is connected to the power supply voltage VDD, the drain of M2 is connected to the source of M3, the drain of M3 is connected to one end of the current source I2, and the other end of the current source I2 is grounded.

[0041] In the load branch, the source of M4 is connected to the power supply voltage VDD, the drain of M4 is connected to the source of M5, the drain of M5 is connected to one end of the first resistor R1 and the non-inverting input end of the amplifier, and the other end of the first resistor R1 is grounded.

[0042] It should be understood that the driving branch including M2 and M3 and the load branch form a cascode current mirror, because the gate of M2 is connected to the drain of M3, which significantly improves the output impedance of the current mirror. Without loss of generality, the driving branch of the current mirror includes a plurality of MOS transistors cascaded between a first power supply voltage and one end of a first current source, the other end of the first current is grounded, and the gates of the plurality of first MOS transistors are connected to each other and to one end of the first current source.

[0043] In addition, the gate-source capacitance is the parasitic capacitance between the gate and source of the MOS tube, and the gate-drain capacitance is the parasitic capacitance between the gate and drain of the MOS tube. Generally speaking, the gate-source capacitance of the MOS tube is greater than the gate-drain capacitance, that is, the gate-source capacitance of the first MOS tube is greater than the gate-drain capacitance. In this example, the gate-drain capacitance between the output end of the amplifier and the drive output end is small, which reduces external EMI interference.

[0044] Specifically, Figure 4 As shown, the inverting input terminal of the amplifier is the second input terminal, the first MOS tube is M0, the source of M0 is connected to one end of the second resistor R2 and the inverting input terminal, the other end of the second resistor R2 is grounded, and the gate of M0 is connected to the output terminal of the amplifier for receiving the voltage control signal VG. The drain of M0 is connected to the drive pull-up circuit and the drive output terminal. For example, the drain of M0 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the drive pull-up circuit and the drive output terminal, thereby preventing the current on M0 from flowing back to the bus and affecting the performance of the bus. As an example, the drive pull-up circuit includes a second diode D2 connected in series and a third resistor R3 as an output load resistor, the anode of the second diode D2 is connected to the second power supply of the control device (for example, the power supply terminal of the battery module of the control device), the cathode of the second diode D2 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the drive output terminal and the drain of M0.

[0045] It should be understood that the first power supply voltage in the text can be provided by the power supply end of the bus driving unit after being processed by a voltage stabilizing circuit such as LDO (Low Dropout Regulator), and the second power supply voltage can be directly supplied by the power supply end or supplied after being stepped down by a diode. Without loss of generality, the source of the first MOS tube is connected to the second input end and grounded through a second resistor, the drain of the first MOS tube is connected to one end of the driving pull-up circuit and the driving output end, the other end of the driving pull-up circuit is connected to the second power supply voltage, and the gate of the first MOS tube is connected to the output end of the amplifier circuit. In other words, when the level state of the bus signal is high, the voltage control signal sent from the output end is pulled down to below the preset voltage threshold, and the first MOS tube is turned off when the voltage control signal is lower than the preset voltage threshold, thereby improving the reliability of the switch circuit and reducing the complexity of the device.

[0046] Further, the pull-down circuit is connected between the output terminal of the amplifier circuit and the ground, and the pull-down circuit is used to receive the bus signal, and absorb the signal current of the output terminal of the amplifier when the level state of the bus signal is high, so as to pull the voltage control signal down to a level lower than the preset voltage threshold. The pull-down function of the pull-down circuit is realized by controlling the bus signal through a simple configuration.

[0047] In addition, the pull-down circuit is further used to: turn off the pull-down function of the pull-down circuit when the level state of the bus signal is at a low level, and the output end of the amplifier pulls up the voltage control signal to a level greater than the preset voltage threshold. Figure 4 As shown, the pull-down circuit includes M6 and M7 as N-type MOS tubes, the drain of M6 is connected to the input end of the amplifier, and the gate of M6 is used to receive bus signals, for example, connected to the controller. The source of M6 is connected to one end of the second current source I3, and the other end of the second current source I3 is grounded. In addition, the drain of M7 is connected to the input end of the amplifier; the gate of M7 is used to receive bus signals, for example, connected to the controller; the source of M7 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is grounded.

[0048] In addition, when the bus signal TXD is at a low level, M6 and M7 are turned off, the amplifier works normally, the current I is equal to the mirror current I2 output by the current mirror, the current I flows through the first resistor R1 to generate a voltage VA, and according to the negative feedback characteristics of the amplifier, the voltage VB across the second resistor R2 is equal to VA, that is, IOUT on the switch unit side is equal to (R1 / R2)*I. Generally speaking, when the resistance value of the first resistor R1 is set to be sufficiently greater than the resistance value of the second resistor R2, the driving capability of the first MOS tube M0 when it is turned on can pull the level of the driving output end to a low level (for example, a dominant level).

[0049] Without loss of generality, the pull-down circuit includes a second MOS tube and a third MOS tube, the drain of the second MOS tube and the drain of the third MOS tube are connected to the output end of the amplifier circuit, the gate of the second MOS tube and the gate of the third MOS tube are used to receive the bus signal, the source of the second MOS tube is grounded through the second current source, and the source of the second MOS tube is grounded through the first capacitor.

[0050] Further, when the bus signal TXD is at a low level, M6 and M7 are turned off, and the control voltage VG of the switch circuit is pulled up to a high level. When the bus signal TXD is at a high level, M6 and M7 are turned on, the second current source I3 is connected to the first capacitor C1, C1 is slowly discharged through the second current source I3, and the VG voltage is slowly reduced, so that M0 is slowly turned off, that is, the slew rate of the voltage control signal is alleviated by the second current source and the first capacitor, reducing the electromagnetic interference of the bus driving unit to the outside.

[0051] In addition, the amplifier can be connected to the first power supply voltage through the current source I4, and the current of the second current source I3 (for example, 2*IB) is greater than the current of the current source I4 (for example, IB). Therefore, the current of the voltage control signal output at the output end is approximately the current of the current source I4, and the second current source I3 can reliably pull down the voltage control signal at the output end of the amplifier.

[0052] Furthermore, the amplifier circuit may be a rail-to-rail amplifier. The first input terminal is a non-inverting input terminal of the rail-to-rail amplifier, and the second input terminal is an inverting input terminal of the rail-to-rail amplifier.

[0053] As described above, the voltage VB across the second resistor R2 is equal to VA, that is, IOUT on the switch unit side is equal to (R1 / R2)*I. Therefore, the pull-down driving capability of the first MOS tube can be adjusted by adjusting the resistance value of the first resistor R1. Generally speaking, for the linear gain range of the amplifier, when the resistance value of the first resistor R1 and the current I are large enough, VA is large enough to obtain a sufficiently large pull-down driving capability. When VA increases significantly relative to the first power supply voltage of the amplifier, the amplifier may not operate in the linear gain range, resulting in a decrease in the feedback loop gain of the amplifier. Through the solution of this example, the rail-to-rail amplifier is conducive to ensuring the linear amplification characteristics of the amplifier in the case of an input voltage range between the ground and the first power supply voltage, and the reliable driving capability of the amplifier can be achieved when it is close to the first power supply voltage or the ground.

[0054] In some examples, the rail-to-rail amplifier includes: an input stage circuit and an output stage circuit, the input stage circuit includes a first differential circuit and a second differential circuit, wherein the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the first differential circuit, and the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the second differential circuit. When the voltage difference between the input signal at the input terminal and the first power supply voltage is greater than the voltage difference between the input signal and the ground, the output terminal of the first differential circuit is connected to the output stage circuit. When the voltage difference between the input signal and the first power supply voltage is less than the voltage difference between the input signal and the ground, the output terminal of the second differential circuit is connected to the output stage circuit.

[0055] More specifically, if Figure 5 As shown, the first input terminal is VIP, the second input terminal is VIN, the power supply terminal provides a first power supply voltage VDD, and the ground terminal provides ground. Among them, M21, M22, M25, M26, M27, M28 and M29 are N-type MOS tubes, and M10M11M12M13M14 are P-type MOS tubes.

[0056] The first differential circuit includes M21 and M22, and the second differential circuit includes M23 and M24, wherein the gate of M21 is connected to the gate of M24 and connected to the first input terminal, and the gate of M22 is connected to the gate of M23 and connected to the second input terminal.

[0057] The source of M21 is connected to the source of M22 and to the drain of M25, and the source of M25 is grounded. The source of M23 is connected to the source of M24 and to the drain of M14, and the source of M124 is connected to the first power supply voltage. The gate of M25 is connected to the reference voltage VB4.

[0058] The output stage circuit includes a first current mirror and a second current mirror, the first current mirror includes M12, M13, M10 and M11, and the second current mirror includes M28, M29, M16 and M27. In the first current mirror, the source of M12 and the source of M13 are connected to the first power supply voltage, the source of M10 is connected to the drain of M12, and the source of M11 is connected to the drain of M13. In the second current mirror, the source of M26 and the source of M27 are grounded, the drain of M26 is connected to the source of M28, and the drain of M27 is connected to the source of M29. In the second current mirror, the drain of M28 is connected to the drain of M10, the drain of M29 is connected to the drain of M11, and is connected to the output end of the amplifier.

[0059] In the first current mirror, the gate of M14, the gate of M12 and the gate of M13 are connected and connected to the reference voltage VB1. In the second current mirror, the gate of M28, the gate of M29, the gate of M26, the gate of M27 and the drain of M28 are connected and connected to the reference voltage VB.

[0060] The drain of M12 in the first current mirror is connected to the drain of M21 in the first differential circuit, and the drain of M13 in the first current mirror is connected to the drain of M22 in the first differential circuit.

[0061] The drain of M26 in the second current mirror is connected to the drain of M24 in the second differential circuit, and the drain of M27 in the second current mirror is connected to the drain of M23 in the second differential circuit.

[0062] It should be understood that the ground in this article can be provided by a ground terminal, and the first power supply voltage can be a stable voltage provided by a power supply terminal after being processed by a voltage stabilization circuit such as an LDO (Low Dropout Regulator).

[0063] Thus far, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired results. Additionally, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing may be advantageous.

[0064] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0065] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0066] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0067] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A bus driver unit, characterized in that: include: an amplifier circuit, wherein a first input terminal of the amplifier circuit is connected to a reference voltage, and an output terminal of the amplifier circuit is used to output a voltage control signal; a switch circuit, wherein a control end of the switch circuit is connected to an output end of the amplifier circuit, and is used to shut down when the voltage control signal is lower than a preset voltage threshold, one end of the switch circuit is connected to a second input end of the amplifier circuit and is grounded through a resistor to form a negative feedback branch of the amplifier circuit, wherein the other end of the switch circuit is connected to a driving output end of a bus signal and a driving pull-up circuit; A pull-down circuit is used to receive the bus signal and pull the voltage control signal down to a level lower than the preset voltage threshold when the level state of the bus signal is a high level.

2. The bus driver unit according to claim 1, characterized in that: The amplifier circuit also includes a current mirror, multiple first current sources and a first resistor. The multiple driving branches of the current mirror are respectively grounded through the multiple first current sources, one end of the first resistor is grounded, and the other end of the first resistor is connected to the load branch of the current mirror and the first input end of the amplifier circuit for generating the reference voltage.

3. The bus driver unit according to claim 2, characterized in that: The driving branch of the current mirror includes a plurality of MOS tubes cascaded between a first power supply voltage and one end of the first current source, the other end of the first current is grounded, and the gates of the plurality of first MOS tubes are connected to each other and to one end of the first current source.

4. The bus driver unit according to claim 1, characterized in that: The switch circuit includes a first MOS tube, which is an N-type MOS tube. The source of the first MOS tube is connected to the second input terminal and is grounded through a second resistor. The drain of the first MOS tube is connected to one end of the driving pull-up circuit, namely, the driving output terminal, through a first diode. The other end of the driving pull-up circuit is connected to a second power supply voltage. The gate of the first MOS tube is connected to the output terminal of the amplifier circuit.

5. The bus driver unit according to claim 1, characterized in that: The pull-down circuit is connected between the output end of the amplifier circuit and the ground. The pull-down circuit is used to receive the bus signal and absorb the signal current at the output end of the amplifier when the level state of the bus signal is a high level to pull the voltage control signal down to below the preset voltage threshold.

6. The bus driver unit according to claim 5, characterized in that: The pull-down circuit is further used to: turn off the pull-down function of the pull-down circuit when the level state of the bus signal is at a low level, and the output end of the amplifier pulls up the voltage control signal to a level greater than the preset voltage threshold.

7. The bus driver unit according to claim 5, characterized in that: The pull-down circuit includes a second MOS tube and a third MOS tube, the drain of the second MOS tube and the drain of the third MOS tube are connected to the output end of the amplifier circuit, the gate of the second MOS tube and the gate of the third MOS tube are used to receive the bus signal, the source of the second MOS tube is grounded through a second current source, and the source of the second MOS tube is grounded through a first capacitor.

8. The bus driver unit according to claim 1, characterized in that: The amplifier circuit is a rail-to-rail amplifier, the first input end is a non-inverting input end of the rail-to-rail amplifier, and the second input end is an inverting input end of the rail-to-rail amplifier.

9. The bus driver unit according to claim 8, characterized in that: The rail-to-rail amplifier comprises: an input stage circuit and an output stage circuit, the input stage circuit comprises a first differential circuit and a second differential circuit, wherein the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the first differential circuit, and the first input terminal and the second input terminal are respectively connected to the first input terminal and the second input terminal of the second differential circuit; Wherein, when the voltage difference between the input signal at the input end and the first power supply voltage is greater than the voltage difference between the input signal and the ground, the output end of the first differential circuit is connected to the output stage circuit; Wherein, when the voltage difference between the input signal and the first power supply voltage is smaller than the voltage difference between the input signal and the ground, the output end of the second differential circuit is connected to the output stage circuit.

10. A control device, characterized in that: include: The bus driver unit according to any one of claims 1 to 9; as well as The control unit is connected to the bus driving unit and is used to output a bus signal.

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