Interface circuit and I2C communication system

Abstract

The utility model relates to the technical field of power electronics, and discloses an interface circuit and an I2C communication system, the interface circuit comprises a voltage limiting circuit, a current limiting circuit, a first clamping circuit and an energy storage circuit, a first end of the voltage limiting circuit is connected with a power supply end of a main controller, and a second end of the current limiting circuit is connected with a second clamping circuit; the second end of the current limiting circuit is connected with the communication end of the main controller and the first end of the current limiting circuit; the second end of the current limiting circuit is connected with the first end of the first clamping circuit and the communication end of slave equipment; the second end of the first clamping circuit is connected with the first end of the energy storage circuit and the power supply end of the slave equipment; and the second end of the energy storage circuit is grounded, and when the voltage at the two ends of the energy storage circuit reaches the preset voltage, the energy storage circuit discharges to enable the slave equipment to start working. According to the invention, the number of wires between the master controller and the slave device can be reduced, and high voltage and impact current at an interface during hot plugging can be limited on the premise of not influencing a normal communication function.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and particularly relates to an interface circuit and an I2C communication system. Background Art

[0002] Hot plugging, also known as hot swapping, that is, "hot plugging and unplugging", means that hardware can be plugged in or unplugged while the device is operating. When combined with appropriate software, peripheral devices that support hot plugging can be inserted or removed without turning off the power, and it will not cause the host or peripheral devices to burn out. The requirements for software and hardware for hot plugging also include relevant requirements for power supply, signal, and ground wire.

[0003] The I2C bus connects the master controller and the slave device. The I2C bus itself does not have the function of hot plugging. If the I2C bus device is plugged or unplugged in the live working state, it may cause device damage. Especially when the bus length is relatively long (such as more than 1 meter), due to the inductance effect of the long wire, a high voltage is easily induced at one end during hot plugging. Repeatedly plugging and unplugging the slave device connection may damage the master controller and the slave device. If a dedicated I2C bus hot plugging interface chip protection circuit is added, the cost will be too high. At the same time, the slave device has requirements for low cost and low power consumption. Currently, there are a total of four wires between the master controller and the slave device end, namely the power supply wire, the ground wire, and the I2C bus (SCL, SDA), and the cost is relatively high. Summary of the Utility Model

[0004] Therefore, the technical problem to be solved by the utility model is to solve the problem of high cost caused by the need to connect a power supply wire between the master controller and the slave device end in the prior art, so as to provide an interface circuit and an I2C communication system.

[0005] To achieve the above object, the utility model provides the following technical solutions:

[0006] In the first aspect, the utility model provides an interface circuit for realizing signal transmission between a master controller and a slave device. The interface circuit includes: a voltage limiting circuit, a current limiting circuit, a first clamping circuit, and an energy storage circuit. Among them, for the voltage limiting circuit, its first end is connected to the power supply end of the master controller, its second end is connected to the communication end of the master controller and the first end of the current limiting circuit, and it is used to limit the voltage magnitude between the power supply end and the communication end of the master controller; for the current limiting circuit, its second end is connected to the first end of the first clamping circuit and the communication end of the slave device, and it is used to limit the magnitude of the current flowing into the slave device; for the first clamping circuit, its second end is connected to the first end of the energy storage circuit and the power supply end of the slave device, and it is used to clamp the voltage of the communication end of the slave device within a preset range and charge the energy storage circuit based on the voltage at the second end of the current limiting circuit; for the energy storage circuit, its second end is grounded. When the voltage across the energy storage circuit reaches a preset voltage, the energy storage circuit discharges to make the slave device start to work.

[0007] For the interface circuit provided by the present utility model, when a hot plug and unplug operation is performed between a slave device and a main controller, a current limiting circuit can limit the inrush current on the interface connection line, a voltage limiting circuit can limit the high voltage on the interface connection line on the main controller side, a first clamping circuit can limit the high voltage on the interface connection line on the slave device side, and the power supply terminal of the slave device does not need to be directly connected to the power supply terminal of the main controller. Instead, the electrical energy released by the energy storage circuit is used to maintain normal operation, saving a power supply cable connected to the main controller and reducing the circuit cost.

[0008] In an optional implementation manner, the voltage limiting circuit includes: a pull-up circuit and a second clamping circuit. Among them, for the pull-up circuit, its first end is connected to the power supply terminal of the main controller and the first end of the second clamping circuit, and its second end is connected to the second end of the second clamping circuit and the communication terminal of the main controller; for the second clamping circuit, it is used to provide a discharge path for the overvoltage of the communication terminal of the main controller and clamp the voltage of the communication terminal of the main controller within a preset range by using the pull-up circuit.

[0009] For the interface circuit provided by the present utility model, after the pull-up circuit pulls up the voltage of the communication terminal of the main controller to the power supply voltage of the main controller, on the one hand, the second clamping circuit can clamp the voltage of the communication terminal of the main controller to the power supply voltage to provide a charging voltage for the energy storage circuit; on the other hand, it can provide a discharge path for the overvoltage of the communication terminal of the main controller, so that the main controller is not damaged by the overvoltage.

[0010] In an optional implementation manner, the communication terminal of the main controller includes a first main communication terminal and a second main communication terminal. The pull-up circuit includes: a first resistor and a second resistor. Among them, for the first resistor, its first end is connected to the first end of the second resistor and the first end of the second clamping circuit, and its second end is connected to the first main communication terminal and the second end of the second clamping circuit; for the second resistor, its second end is connected to the second main communication terminal and the second end of the second clamping circuit.

[0011] In an optional implementation manner, the second clamping circuit includes: a first clamping circuit and a second clamping circuit. Among them, for the first clamping circuit, its first end is connected to the power supply terminal of the main controller and the first end of the second clamping circuit, its second end is connected to the second end of the second clamping circuit and then grounded, and its third end is connected to the first main communication terminal, and it is used to provide a discharge path for the overvoltage of the first main communication terminal; for the second clamping circuit, its third end is connected to the second main communication terminal, and it is used to provide a discharge path for the overvoltage of the second main communication terminal.

[0012] In an optional implementation manner, the first clamping circuit includes: a first diode and a second diode. Among them, for the first diode, its cathode is connected to the first end of the second clamping circuit, and its anode is connected to the cathode of the second diode and the first main communication terminal; for the second diode, its anode is connected to the second end of the second clamping circuit.

[0013] In an alternative embodiment, the second clamping circuit includes: a third diode and a fourth diode. Wherein, for the third diode, its cathode is connected to the first end of the first clamping circuit, and its anode is connected to the cathode of the fourth diode and the second main communication terminal; for the fourth diode, its anode is connected to the second end of the first clamping circuit.

[0014] In an alternative embodiment, the current limiting circuit includes: at least two third resistors connected in series.

[0015] In an alternative embodiment, the energy storage circuit includes: a first capacitor and a second capacitor. Wherein, for the first capacitor, its first end is connected to the second end of the first clamping circuit and the first end of the second capacitor, and its second end is grounded after being connected to the second end of the second capacitor; when the voltages across the first capacitor and the second capacitor both reach the preset voltage, the first capacitor and the second capacitor discharge, causing the slave device to start working.

[0016] In an alternative embodiment, the interface circuit further includes: a transient suppression diode, which is connected in parallel with the energy storage circuit and is used to suppress overvoltage at the power supply terminal of the slave device.

[0017] In a second aspect, the present utility model provides an I2C communication system, including: a master controller, a slave device, a master controller circuit board, a slave device circuit board, and the interface circuit of the first aspect. Wherein, at least one third resistor among the master controller, the voltage limiting circuit, and the current limiting circuit is integrated on the master controller circuit board; at least one third resistor among the slave device, the first clamping circuit, the energy storage circuit, and the current limiting circuit is integrated on the slave device circuit board; the communication terminal of the master controller is connected to the communication terminal of the slave device through an I2C bus; the grounding terminal of the master controller is connected to the grounding terminal of the slave device.

[0018] For the I2C communication system provided by the present utility model, compared with the traditional I2C communication system, one power cable between the slave device and the master controller is reduced. The power supply terminal of the slave device does not need to be directly connected to the power supply terminal of the master controller. Instead, the electrical energy released by the energy storage circuit is used to maintain normal operation, saving a power supply cable connected to the master controller and reducing the cost of the communication system. When hot plugging and unplugging between the slave device and the master controller, the current limiting circuit can limit the impact current on the interface connection line, the voltage limiting circuit can limit the high voltage on the interface connection line on the master controller side, and the first clamping circuit can limit the high voltage on the interface connection line on the slave device side. Description of the Drawings

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific 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.

[0020] Figure 1 It is a composition diagram of a specific example of the interface circuit according to an embodiment of the present invention;

[0021] Figure 2 It is a composition diagram of another specific example of the interface circuit according to an embodiment of the present invention;

[0022] Figure 3 It is a structural diagram of a specific circuit of the interface circuit according to an embodiment of the present invention;

[0023] Figure 4 It is a composition diagram of a specific example of the I2C communication system according to an embodiment of the present invention. Specific embodiments

[0024] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can also be the communication inside two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0027] In addition, the technical features involved in different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0028] The existing I2C bus itself does not have the function of hot plugging. When the main controller and the slave device are plugged or unplugged while in the powered-on state, it may cause damage to the device. And usually, a total of 4 wires including the I2C bus (which contains two communication lines inside), the power line, and the ground line are required between the main controller and the slave device, resulting in a relatively high cost. Therefore,

[0029] This embodiment provides an interface circuit, as Figure 1 shown, which is used to realize the signal transmission between the main controller and the slave device. The interface circuit includes: a voltage-limiting circuit 1, a current-limiting circuit 2, a first clamping circuit 3, and an energy storage circuit 4. Among them, for the voltage-limiting circuit 1, its first end is connected to the power supply terminal of the main controller, and its second end is connected to the communication terminal of the main controller (i.e., the SDA and SCL terminals of the main controller) and the first end of the current-limiting circuit 2, and it is used to limit the voltage between the power supply terminal and the communication terminal of the main controller. For the current-limiting circuit 2, its second end is connected to the first end of the first clamping circuit 3 and the communication terminal of the slave device, and it is used to limit the magnitude of the current flowing into the slave device.

[0030] Specifically, Figure 1 in, the interface circuit is connected to the slave device using the I2C bus. In order to avoid damage to the main controller and the slave device caused by the overvoltage generated on the I2C bus during the hot plugging process of the slave device, the voltage-limiting circuit 1 is arranged between the I2C bus and the power supply terminal of the main controller to limit the maximum voltage on the I2C bus not exceeding the power supply voltage VDD of the main controller. At the same time, in order to avoid damage to the main controller and the slave device caused by the impact current generated on the I2C bus during the hot plugging process of the slave device, a current-limiting circuit 2 is arranged on the I2C bus to limit the overcurrent between the communication terminals of the main controller and the slave device.

[0031] It should be noted that both the voltage-limiting circuit and the current-limiting circuit can be composed of structures such as diodes and resistors, and the specific circuit structure is not limited here.

[0032] Figure 1In it, there is a first clamping circuit 3, whose second end is connected to the first end of the energy storage circuit 4 and the power supply end of the slave device. It is used to clamp the voltage of the communication end of the slave device (i.e., the SDA and SCL ends of the slave device) within a preset range, and charge the energy storage circuit 4 based on the voltage at the second end of the current limiting circuit 2; the energy storage circuit 4, whose second end is grounded. When the voltage across the energy storage circuit 4 reaches the preset voltage, the energy storage circuit 4 discharges to make the slave device start to work.

[0033] Specifically, Figure 1 In it, in order to avoid damage to the main controller and the slave device caused by overvoltage generated on the I2C bus during the hot plugging of the slave device, the slave device side uses the first clamping circuit 3 to limit the overvoltage on the I2C bus on the slave device side, and limits the voltage at the communication end of the slave device not to exceed the supply voltage VDD at most. At the same time, in order to reduce the circuit cost, the supply voltage of the slave device is not directly obtained from the supply end of the main controller, that is, the supply end of the slave device is not directly connected to the supply end of the main controller. Instead, the first clamping circuit 3 is used to transfer the current on the I2C bus to the energy storage circuit 4, so that the energy storage circuit 4 accumulates charges under the action of the current and then releases them to supply power to the slave device, thus saving the cost of a power supply line.

[0034] For the interface circuit provided in this embodiment, when hot plugging occurs between the slave device and the main controller, the current limiting circuit can limit the impact current on the interface connection line, the voltage limiting circuit can limit the high voltage on the interface connection line on the main controller side, the first clamping circuit can limit the high voltage on the interface connection line on the slave device side, and the power supply end of the slave device does not need to be directly connected to the power supply end of the main controller. Instead, the electric energy released by the energy storage circuit is used to maintain normal operation, saving a power supply cable connected to the main controller and saving circuit cost.

[0035] In some optional implementation manners, such as Figure 2 shown, the voltage limiting circuit 1 includes: a pull-up circuit 11 and a second clamping circuit 12. Among them, for the pull-up circuit 11, its first end is connected to the power supply end of the main controller and the first end of the second clamping circuit 12, and its second end is connected to the second end of the second clamping circuit 12 and the communication end of the main controller.

[0036] Specifically, as Figure 3 shown, the communication end of the main controller includes a first main communication end (i.e., the SDA end) and a second main communication end (i.e., the SCL end). The pull-up circuit 11 includes: a first resistor R1 and a second resistor R2. Among them, for the first resistor R1, its first end is connected to the first end of the second resistor R2 and the first end of the second clamping circuit 12, and its second end is connected to the first main communication end and the second end of the second clamping circuit 12; for the second resistor R2, its second end is connected to the second main communication end and the second end of the second clamping circuit 12.

[0037] Specifically,Figure 3 In the figure, the first resistor R1 and the second resistor R2 in the pull-up circuit 11 respectively pull up the voltages on the SDA communication line and the SCL communication line in the I2C bus to the supply voltage of the main controller and maintain them at VDD. The second clamping circuit 12 internally contains a ground connection point (voltage is 0V), one end of which receives the supply voltage VDD. While providing a path for discharging the overvoltage at the communication end of the main controller to the ground, it can also clamp the voltage at the communication end of the main controller between 0 and VDD.

[0038] In some alternative embodiments, such as Figure 3 shown, the second clamping circuit includes: a first clamping circuit 121 and a second clamping circuit 122. Among them, for the first clamping circuit 121, its first end is connected to the supply end of the main controller and the first end of the second clamping circuit 122, its second end is connected to the second end of the second clamping circuit 122 and then grounded, and its third end is connected to the first main communication end, and it is used to provide a discharging path for the overvoltage at the first main communication end; for the second clamping circuit 122, its third end is connected to the second main communication end, and it is used to provide a discharging path for the overvoltage at the second main communication end.

[0039] Specifically, as Figure 3 shown, the first clamping circuit 121 includes: a first diode D1 and a second diode D2. Among them, for the first diode D1, its cathode is connected to the first end of the second clamping circuit 122, and its anode is connected to the cathode of the second diode D2 and the first main communication end; for the second diode D2, its anode is connected to the second end of the second clamping circuit 122.

[0040] Specifically, as Figure 3 shown, the second clamping circuit 12 includes: a third diode D3 and a fourth diode D4. Among them, for the third diode D3, its cathode is connected to the first end of the first clamping circuit 121, and its anode is connected to the cathode of the fourth diode D4 and the second main communication end; for the fourth diode D4, its anode is connected to the second end of the first clamping circuit 121.

[0041] Specifically, Figure 3 in the figure, the first diode D1 to the fourth diode D4 are all used to limit the voltage on the I2C bus and keep the voltage between the supply voltage VDD and the ground. The diode has the characteristic of unidirectional conduction. When there is an overvoltage higher than VDD on the I2C bus, the overvoltage will be pulled down to VDD through the diode connected between the I2C bus and the supply end, that is, when there is an overvoltage higher than VDD on the SDA communication line or the SCL communication line, the overvoltage will be pulled down to VDD through the first diode D1 or the third diode D3.

[0042] Specifically, Figure 3In the case where there is a negative voltage lower than the ground on the I2C bus, the negative voltage will raise the voltage on the I2C bus to the ground level through the reverse diode connected to the ground. That is, when there is an overvoltage higher than VDD on the SDA line or the SCL line, the overvoltage will be raised to the ground level through the second diode D2 or the fourth diode D4. Therefore, the voltage on the I2C bus exceeding the power supply and the ground will be discharged to the power supply and the ground through the first diode D1 to the fourth diode D4, thereby ensuring that the voltage on the signal line is within the allowable range and realizing the function of voltage limiting.

[0043] In some alternative embodiments, such as Figure 3 shown, the current limiting circuit includes: at least two third resistors (R3 or R4 or R5 or R6) connected in series.

[0044] Optionally, Figure 3 in, since the I2C bus includes the SDZ communication line and the SCL communication line, and in order to limit the current magnitude of the communication terminals on the master controller side and the slave device side respectively and improve the reliability of the interface circuit, at least two current limiting resistors (i.e., the third resistors) should be provided on each communication line. Those skilled in the art can set the number of the third resistors on each communication line according to actual requirements, which is not limited herein.

[0045] In some alternative embodiments, such as Figure 3 shown, the energy storage circuit 4 includes: a first capacitor C1 and a second capacitor C2. Among them, for the first capacitor C1, its first end is connected to the second end of the first clamping circuit 3 and the first end of the second capacitor C2, and its second end is connected to the second end of the second capacitor C2 and then grounded.

[0046] Specifically, Figure 3 in, when the slave device is connected to the master controller, the I2C bus is at a high level, and there is a current on the I2C bus flowing into the first capacitor C1 and the second capacitor C2 through the diodes D6 and D7. The charges in the first capacitor C1 and the second capacitor C2 gradually accumulate for charging. When the voltage across the first capacitor C1 and the second capacitor C2 reaches above the preset voltage and reaches the operating voltage of the power supply terminal of the slave device, the first capacitor C1 and the second capacitor C2 discharge to enable the slave device to start normal operation.

[0047] Specifically, Figure 3 in, the interface circuit further includes: a transient suppression diode D9, which is connected in parallel with the energy storage circuit 4 and is used to suppress the overvoltage at the power supply terminal of the slave device, prevent the peak voltage from exceeding the standard during the hot plugging of the slave device, and limit the overvoltage on the I2C bus not to exceed the voltage range allowed by the slave device.

[0048] This embodiment provides an I2C communication system, such as Figure 4As shown in the figure, it includes: a main controller, a slave device, a main controller circuit board, a slave device circuit board, and the interface circuit of the above embodiments and any of their optional implementation manners. Among them, at least one third resistor in the main controller, the voltage limiting circuit 1, and the current limiting circuit is integrated on the main controller circuit board; at least one third resistor in the slave device, the first clamping circuit 3, the energy storage circuit 4, and the current limiting circuit is integrated on the slave device circuit board; the communication terminal of the main controller is connected to the communication terminal of the slave device through the I2C bus; the grounding terminal of the main controller is connected to the grounding terminal of the slave device.

[0049] Specifically, Figure 4 In this case, both the main controller and the slave device are integrated on the corresponding circuit boards. The third resistor on each circuit board plays a current limiting role. The main controller circuit board and the slave device circuit board are connected only by three lines, namely the I2C bus (which includes two lines, the SDA communication line and the SCL communication line inside) and the ground wire, reducing the cost of the communication system.

[0050] It should be noted that the functions and working principles of the components in this embodiment are the same as those of the above embodiments and any of their optional implementation manners, and will not be elaborated here.

[0051] The I2C communication system provided in this embodiment, compared with the traditional I2C communication system, reduces a power cable between the slave device and the main controller. The power supply terminal of the slave device does not need to be directly connected to the power supply terminal of the main controller. Instead, it uses the electric energy released by the energy storage circuit to maintain normal operation, saving a power supply cable connected to the main controller and saving the cost of the communication system. When hot plugging and unplugging between the slave device and the main controller, the current limiting circuit can limit the impact current on the interface connection line, the voltage limiting circuit can limit the high voltage on the interface connection line on the main controller side, and the first clamping circuit can limit the high voltage on the interface connection line on the slave device side.

[0052] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An interface circuit, characterized in that: It is used to realize signal transmission between the main controller and the slave device. The interface circuit includes: a voltage limiting circuit, a current limiting circuit, a first clamping circuit and an energy storage circuit, wherein: A voltage limiting circuit, a first end of which is connected to the power supply end of the main controller, and a second end of which is connected to the communication end of the main controller and the first end of the current limiting circuit, and is used to limit the voltage between the power supply end and the communication end of the main controller; a current limiting circuit, a second end of which is connected to the first end of the first clamping circuit and the communication end of the slave device, and is used to limit the current flowing into the slave device; a first clamping circuit, the second end of which is connected to the first end of the energy storage circuit and the power supply end of the slave device, and is used to clamp the voltage of the communication end of the slave device within a preset range and charge the energy storage circuit based on the voltage of the second end of the current limiting circuit; The energy storage circuit has a second end grounded. When the voltage across the energy storage circuit reaches a preset voltage, the energy storage circuit discharges so that the slave device starts working.

2. The interface circuit according to claim 1, characterized in that: The voltage limiting circuit includes: a pull-up circuit and a second clamping circuit, wherein: a pull-up circuit, a first end of which is connected to a power supply end of the main controller and a first end of the second clamping circuit, and a second end of which is connected to a second end of the second clamping circuit and a communication end of the main controller; The second clamping circuit is used to provide a discharge path for the overvoltage of the communication terminal of the main controller, and to clamp the voltage of the communication terminal of the main controller within a preset range by using the pull-up circuit.

3. The interface circuit according to claim 2, characterized in that: The communication end of the main controller includes a first main communication end and a second main communication end, and the pull-up circuit includes: a first resistor and a second resistor, wherein: a first resistor, a first end of which is connected to the first end of the second resistor and the first end of the second clamping circuit, and a second end of which is connected to the first main communication end and the second end of the second clamping circuit; A second resistor has a second end connected to the second main communication end and the second end of the second clamping circuit.

4. The interface circuit according to claim 3, characterized in that: The second clamping circuit includes: a first clamping circuit and a second clamping circuit, wherein: a first clamping circuit, wherein a first end of the first clamping circuit is connected to a power supply end of the main controller and a first end of the second clamping circuit, a second end of the first clamping circuit is connected to a second end of the second clamping circuit and then grounded, and a third end of the first clamping circuit is connected to the first main communication end, and is used to provide a discharge path for an overvoltage of the first main communication end; The second clamping circuit has a third terminal connected to the second main communication terminal and is used to provide a discharge path for an overvoltage of the second main communication terminal.

5. The interface circuit according to claim 4, characterized in that: The first clamping circuit includes: a first diode and a second diode, wherein: a first diode, a cathode of which is connected to the first end of the second clamping circuit, and an anode of which is connected to the cathode of the second diode and the first main communication end; A second diode has an anode connected to the second end of the second clamping circuit.

6. The interface circuit according to claim 4, characterized in that: The second clamping circuit includes: a third diode and a fourth diode, wherein: a third diode, a cathode of which is connected to the first end of the first clamping circuit, and an anode of which is connected to the cathode of the fourth diode and the second main communication end; A fourth diode has an anode connected to the second end of the first clamping circuit.

7. The interface circuit according to claim 1, characterized in that: The current limiting circuit includes: at least two third resistors connected in series.

8. The interface circuit according to claim 1, characterized in that: The energy storage circuit includes: a first capacitor and a second capacitor, wherein: A first capacitor, a first end of which is connected to the second end of the first clamp circuit and the first end of the second capacitor, and a second end of which is connected to the second end of the second capacitor and then grounded; When the voltages across the first capacitor and the second capacitor both reach a preset voltage, the first capacitor and the second capacitor are discharged so that the slave device starts to work.

9. The interface circuit according to claim 1, characterized in that: Also includes: A transient voltage suppressor diode is connected in parallel with the energy storage circuit and is used to suppress overvoltage at the power supply end of the slave device.

10. An I2C communication system, characterized in that: include: A master controller, a slave device, a master controller circuit board, a slave device circuit board, and an interface circuit as claimed in any one of claims 1 to 9, wherein: The main controller, the voltage limiting circuit and at least one third resistor in the current limiting circuit are all integrated on the main controller circuit board; The slave device, the first clamping circuit, the energy storage circuit and at least one third resistor in the current limiting circuit are all integrated on a slave device circuit board; The communication end of the master controller is connected to the communication end of the slave device via an I2C bus; The ground terminal of the master controller is connected to the ground terminal of the slave device.

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