An interface circuit and an interface device

Abstract

This application provides an interface circuit and an interface device. The interface circuit includes a first protection branch and a second protection branch; both the first end of the first protection branch and the first end of the second protection branch are electrically connected to a positive power supply voltage; the second end of the first protection branch is electrically connected to a first communication pin, and the second end of the second protection branch is electrically connected to a second communication pin; the first protection branch is used to limit the voltage of a first internal node to less than or equal to a first voltage threshold and the voltage of a second internal node to less than or equal to a second voltage threshold when the first communication pin is short-circuited to the bus power supply VBUS pin; the second protection branch is used to limit the voltage of a third internal node to less than or equal to a third voltage threshold and the voltage of a fourth internal node to less than or equal to a fourth voltage threshold when the second communication pin is short-circuited to the bus power supply VBUS pin. This interface circuit can achieve high-voltage short-circuit protection.

Description

Technical Field

[0001] This application relates to the field of integrated circuit technology, and more particularly to an interface circuit and interface device. Background Technology

[0002] In Universal Serial Bus-Power Delivery (USB PD) fast charging, the urgent need for fast charging necessitates high-current charging. High-current charging requires charging cables with electronic marker (E-marker) chips, so the Type-C and PD interface circuits need to support the VCONN power supply function to meet the power supply requirements of the E-marker chip.

[0003] In actual charging, the VBUS and communication pin circuits are easily short-circuited at the charging interface. However, with the increase of PD charging voltage, the charging voltage can support a high voltage of 20V. Thus, the high voltage may cause damage to the interface circuit. Summary of the Invention

[0004] In view of the above problems, embodiments of this application provide an interface circuit and interface device that can realize high voltage short circuit protection.

[0005] In a first aspect, embodiments of this application provide an interface circuit, including: a first protection branch and a second protection branch;

[0006] The first end of the first protection branch and the first end of the second protection branch are both electrically connected to the positive voltage of the power supply. The second end of the first protection branch is electrically connected to the first communication pin, and the second end of the second protection branch is electrically connected to the second communication pin.

[0007] The first protection branch is used to limit the voltage of the first internal node to less than or equal to a first voltage threshold and the voltage of the second internal node to less than or equal to a second voltage threshold when the first communication pin is short-circuited to the bus power supply VBUS pin.

[0008] The second protection branch is used to limit the voltage of the third internal node to less than or equal to a third voltage threshold and the voltage of the fourth internal node to less than or equal to a fourth voltage threshold when the second communication pin is short-circuited with the bus power supply VBUS pin.

[0009] In some embodiments, the first protection branch includes: a first switch, a second switch, and a third switch;

[0010] The first terminal of the first switch and the first terminal of the third switch are both electrically connected to the positive voltage of the power supply. The second terminal of the first switch is electrically connected to the first terminal of the second switch. The control terminals of the first switch and the second switch are both electrically connected to the first power supply voltage VCONN. The second terminals of the second switch and the second terminals of the third switch are both electrically connected to the first communication pin. The control terminal of the third switch is electrically connected to the first communication voltage.

[0011] In some embodiments, the second protection branch includes: a fourth switch, a fifth switch, and a sixth switch;

[0012] The first terminal of the fourth switch and the first terminal of the sixth switch are both electrically connected to the positive voltage of the power supply. The second terminal of the fourth switch is electrically connected to the first terminal of the fifth switch. The control terminals of the fourth switch and the fifth switch are both electrically connected to the second power supply voltage VCONN. The second terminals of the fifth switch and the sixth switch are both electrically connected to the second communication pin. The control terminal of the sixth switch is electrically connected to the second communication voltage.

[0013] In some embodiments, the first protection branch is also used to conduct the positive voltage of the power supply and the first communication pin under the action of the voltage of the first power supply VCONN.

[0014] The second protection branch is also used to conduct the positive voltage of the power supply and the second communication pin under the action of the voltage of the second power supply VCONN.

[0015] In some embodiments, the interface circuit further includes a first current source and a second current source;

[0016] The positive terminals of the first current source and the second current source are both electrically connected to the positive voltage of the power supply. The negative terminal of the first current source is electrically connected to the first terminal of the third switch, and the negative terminal of the second current source is electrically connected to the first terminal of the sixth switch.

[0017] The first protection branch is also used to conduct the negative terminal of the first current source and the first communication pin under the action of the first communication voltage.

[0018] The second protection branch is also used to conduct the negative terminal of the second current source and the second communication pin under the action of the second communication voltage.

[0019] In some embodiments, the interface circuit further includes a first control branch and a second control branch;

[0020] The first terminal of the first control branch and the first terminal of the second control branch are both electrically connected to the output voltage. The second terminal of the first control branch and the second terminal of the second control branch are both grounded. The third terminal of the first control branch is electrically connected to the control terminal of the second switch. The third terminal of the second control branch is electrically connected to the control terminal of the fifth switch. The control terminal of the first control branch is electrically connected to the first power supply VCONN enable signal. The control terminal of the second control branch is electrically connected to the second power supply VCONN enable signal.

[0021] The first control branch is used to connect the control terminal of the second switch and the output voltage, or connect the control terminal of the second switch to ground, under the action of the first power supply VCONN enable signal.

[0022] The second control branch is used to connect the control terminal of the fifth switch and the output voltage, or connect the control terminal of the fifth switch to ground, under the action of the second power supply VCONN enable signal.

[0023] In some embodiments, the first control branch includes: a first control switch, a second control switch, a first pull-up resistor, a first pull-down resistor, and a first clamping diode;

[0024] The first terminal of the first control switch, the first terminal of the first pull-up resistor, and the cathode of the first clamping diode are all electrically connected to the output voltage. The second terminal of the first pull-up resistor is electrically connected to the anode of the first clamping diode, the control terminal of the first control switch, and the first terminal of the second control switch. The second terminal of the first control switch is electrically connected to the first terminal of the first pull-down resistor and the control terminal of the second switch. The second terminal of the first pull-down resistor and the second terminal of the second control switch are both grounded. The control terminal of the second control switch is electrically connected to the first power supply VCONN enable signal.

[0025] In some embodiments, the second control branch includes: a third control switch, a fourth control switch, a second pull-up resistor, a second pull-down resistor, and a second clamping diode;

[0026] The first terminal of the third control switch, the first terminal of the second pull-up resistor, and the cathode of the second clamping diode are all electrically connected to the output voltage. The second terminal of the second pull-up resistor is electrically connected to the anode of the second clamping diode, the control terminal of the third control switch, and the first terminal of the fourth control switch. The second terminal of the third control switch is electrically connected to the first terminal of the second pull-down resistor and the control terminal of the fifth switch. The second terminal of the second pull-down resistor and the second terminal of the fourth control switch are both grounded. The control terminal of the fourth control switch is electrically connected to the second power supply VCONN enable signal.

[0027] In some embodiments, the interface circuitry further includes a third control branch and a fourth control branch;

[0028] The first terminal of the third control branch and the first terminal of the fourth control branch are both electrically connected to the output voltage. The second terminal of the third control branch and the second terminal of the fourth control branch are both grounded. The third terminal of the third control branch is electrically connected to the control terminal of the third switch. The third terminal of the fourth control branch is electrically connected to the control terminal of the sixth switch. The control terminal of the third control branch is electrically connected to the first communication enable signal. The control terminal of the fourth control branch is electrically connected to the second communication enable signal.

[0029] The third control branch is used to connect the control terminal of the third switch and the output voltage, or connect the control terminal of the third switch to ground, under the action of the first communication enable signal.

[0030] The fourth control branch is used to connect the control terminal of the sixth switch and the output voltage, or connect the control terminal of the sixth switch to ground, under the action of the second communication enable signal.

[0031] In some embodiments, the third control branch includes: a fifth control switch, a sixth control switch, a third pull-up resistor, a third pull-down resistor, and a third clamping diode;

[0032] The first terminal of the fifth control switch, the first terminal of the third pull-up resistor, and the cathode of the third clamping diode are all electrically connected to the output voltage. The second terminal of the third pull-up resistor is electrically connected to the anode of the third clamping diode, the control terminal of the fifth control switch, and the first terminal of the sixth control switch. The second terminal of the fifth control switch is electrically connected to the first terminal of the third pull-down resistor and the control terminal of the third switching transistor. The second terminal of the third pull-down resistor and the second terminal of the sixth control switch are both grounded. The control terminal of the sixth control switch is electrically connected to the first communication enable signal.

[0033] In some embodiments, the fourth control branch includes: a seventh control switch, an eighth control switch, a fourth pull-up resistor, a fourth pull-down resistor, and a fourth clamping diode;

[0034] The first terminal of the seventh control switch, the first terminal of the fourth pull-up resistor, and the cathode of the fourth clamping diode are all electrically connected to the output voltage. The second terminal of the fourth pull-up resistor is electrically connected to the anode of the fourth clamping diode, the control terminal of the seventh control switch, and the first terminal of the eighth control switch. The second terminal of the seventh control switch is electrically connected to the first terminal of the fourth pull-down resistor and the control terminal of the sixth switch. The second terminal of the fourth pull-down resistor and the second terminal of the eighth control switch are both grounded. The control terminal of the eighth control switch is electrically connected to the second communication enable signal.

[0035] Secondly, embodiments of this application provide an interface device, including any of the interface circuits provided in the first aspect.

[0036] In the technical solution of this application embodiment, the interface device circuit includes a first protection branch and a second protection branch. The first end of the first protection branch and the first end of the second protection branch are both electrically connected to the positive voltage of the power supply. The second end of the first protection branch is electrically connected to the first communication pin, and the second end of the second protection branch is electrically connected to the second communication pin. The first protection branch can limit the voltage of the first internal node to less than or equal to a first voltage threshold and the voltage of the second internal node to less than or equal to a second voltage threshold when the first communication pin is short-circuited with the bus power supply VBUS pin. The second protection branch can limit the voltage of the third internal node to less than or equal to a third voltage threshold and the voltage of the fourth internal node to less than or equal to a fourth voltage threshold when the second communication pin is short-circuited with the bus power supply VBUS pin. In this way, when the communication pin is short-circuited with the bus power supply VBUS pin, that is, when the interface circuit is connected to the high voltage charging voltage, the voltage of the internal nodes in the interface circuit can be reduced, avoiding damage to the interface circuit caused by the high voltage short circuit, thereby realizing high voltage short circuit protection.

[0037] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments 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 based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of an interface circuit provided in an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of another interface circuit provided in an embodiment of this application;

[0041] Figure 3 This is a schematic diagram of another interface circuit provided in an embodiment of this application;

[0042] Figure 4 This is a schematic diagram of another interface circuit provided in an embodiment of this application;

[0043] Figure 5 This is a schematic diagram of another interface circuit provided in an embodiment of this application;

[0044] Figure 6 This is a schematic diagram of another interface circuit provided in an embodiment of this application;

[0045] Figure 7 This is a schematic diagram of another interface circuit provided in an embodiment of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and drawings of this application are intended to cover non-exclusive inclusion.

[0048] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0049] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0050] In the description of this application, unless otherwise expressly specified and limited, the terms "connected" and "connected" shall be interpreted broadly. For example, "connected" or "connected" in circuit structure can refer not only to physical connection, but also to electrical connection or signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate element, as long as the circuit is connected. It can also refer to the internal connection of two elements. Signal connection can refer not only to signal connection through circuit, but also to signal connection through a medium, such as radio waves.

[0051] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists, A and B exist simultaneously, or B exists. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0052] In the description of this application, unless otherwise stated, "multiple" and "at least two" mean two or more (including two), and similarly, "multiple groups" and "at least two groups" mean two or more (including two groups).

[0053] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0054] Figure 1 This is a schematic diagram of an interface circuit provided in an embodiment of this application, such as... Figure 1 As shown, the interface circuit 100 includes: a first protection branch 110 and a second protection branch 120.

[0055] The first end of the first protection branch 110 and the first end of the second protection branch 120 are both electrically connected to the positive power supply voltage VDD. The second end of the first protection branch 110 is electrically connected to the first communication pin CC1_PAD, and the second end of the second protection branch 120 is electrically connected to the second communication pin CC2_PAD.

[0056] The first protection branch 110 is used to limit the voltage of the first internal node to less than or equal to a first voltage threshold Vth1 and the voltage of the second internal node to less than or equal to a second voltage threshold Vth2 when the first communication pin CC1_PAD is short-circuited to the bus power supply VBUS pin. The second protection branch 120 is used to limit the voltage of the third internal node to less than or equal to a third voltage threshold Vth3 and the voltage of the fourth internal node to less than or equal to a fourth voltage threshold Vth4 when the second communication pin CC2_PAD is short-circuited to the bus power supply VBUS pin.

[0057] For example, Figure 2 This is a schematic diagram of another interface circuit provided in an embodiment of this application. Figure 2 for Figure 1 Based on the embodiment shown, the first protection branch 110 includes a first switch K1 and a second switch K2. The first terminal of the first switch K1 is electrically connected to the positive power supply voltage VDD, and the second terminal of the first switch K1 is electrically connected to the first terminal of the second switch K2. The control terminals of the first switch K1 and the second switch K2 are both electrically connected to the first power supply voltage VCONN, CC1_VCONN_CP. The second terminal of the second switch K2 is electrically connected to the first communication pin CC1_PAD.

[0058] like Figure 2 As shown, the connection point between the second terminal of the first switch K1 and the first terminal of the second switch K2 is the first internal node A. The control terminal of the second switch K2 is electrically connected to the first power supply voltage VCONN, CC1_VCONN_CP. When the second switch K2 is in the ON state, the voltage VA of the first power supply voltage VCONN, CC1_VCONN_CP, and the voltage VA of the first internal node A satisfy: CC1_VCONN_CP - VA ≥ Vth1', where Vth1' is the threshold voltage of the second switch K2. Obviously, VA ≤ CC1_VCONN_CP - Vth1'. Taking CC1_VCONN_CP - Vth1' as the first voltage threshold Vth1, that is, Vth1 = CC1_VCONN_CP - Vth1', then VA ≤ Vth1.

[0059] When the first communication pin CC1_PAD is short-circuited with the bus power supply pin VBUS, the second switch K2 is in the on state, and the voltage VA of the first internal node A still satisfies: VA≤Vth1. In this way, the voltage VA of the first internal node A can be limited to be less than or equal to the first voltage threshold Vth1.

[0060] See also Figure 2The first protection branch 110 also includes a third switch K3, wherein the first terminal of the third switch K3 is electrically connected to the positive power supply voltage VDD, the second terminal of the third switch K3 is electrically connected to the first communication pin CC1_PAD, and the control terminal of the third switch K3 is electrically connected to the first communication voltage CC1_SRC_CP.

[0061] like Figure 2 As shown, the first terminal of the third switch K3 is the second internal node B. The control terminal of the third switch K3 is electrically connected to the first communication voltage CC1_SRC_CP. When the third switch K3 is in the on state, the voltage VB of the first communication voltage CC1_SRC_CP and the second internal node B satisfies: CC1_SRC_CP - VB ≥ Vth2', where Vth2' is the threshold voltage of the third switch K3. Obviously, VB ≤ CC1_SRC_CP - Vth2'. Taking CC1_SRC_CP - Vth2' as the second voltage threshold Vth2, that is, Vth2 = CC1_SRC_CP - Vth2', then VB ≤ Vth2.

[0062] When the first communication pin CC1_PAD is short-circuited with the bus power supply pin VBUS, the third switch K3 is in the on state, and the voltage VB of the second internal node B still satisfies: VB≤Vth2. In this way, the voltage VB of the second internal node B can be limited to be less than or equal to the second voltage threshold Vth2.

[0063] See also Figure 2 The second protection branch 120 includes a fourth switch K4 and a fifth switch K5. The first terminal of the fourth switch K4 is electrically connected to the positive power supply voltage VDD, and the second terminal of the fourth switch K4 is electrically connected to the first terminal of the fifth switch K5. The control terminals of the fourth switch K4 and the fifth switch K5 are both electrically connected to the second power supply voltage VCONN CC2_VCONN_CP. The second terminal of the fifth switch K5 is electrically connected to the second communication pin CC2_PAD.

[0064] like Figure 2As shown, the connection point between the second terminal of the fourth switch K4 and the first terminal of the fifth switch K5 is the third internal node C. The control terminal of the fifth switch K5 is electrically connected to the second power supply voltage VCONN, CC2_VCONN_CP. When the fifth switch K5 is in the on state, the voltage VC of the second power supply voltage VCONN, CC2_VCONN_CP, and the voltage VC of the third internal node C satisfy: CC2_VCONN_CP - VC ≥ Vth3', where Vth3' is the threshold voltage of the fifth switch K5. Obviously, VC ≤ CC2_VCONN_CP - Vth3'. Taking CC2_VCONN_CP - Vth3' as the third voltage threshold Vth3, that is, Vth3 = CC2_VCONN_CP - Vth3', then VC ≤ Vth3.

[0065] When the second communication pin CC2_PAD is short-circuited with the bus power supply pin VBUS, the fifth switch K5 is in the on state, and the voltage VC of the third internal node C still satisfies: VC≤Vth3. In this way, the voltage VC of the third internal node C can be limited to be less than or equal to the third voltage threshold Vth3.

[0066] See also Figure 2 The second protection branch 120 also includes a sixth switch K6, wherein the first terminal of the sixth switch K6 is electrically connected to the positive power supply voltage VDD, the second terminal of the sixth switch K6 is electrically connected to the second communication pin CC2_PAD, and the control terminal of the sixth switch K6 is electrically connected to the second communication voltage CC2_SRC_CP.

[0067] like Figure 2 As shown, the first terminal of the sixth switch K6 is the fourth internal node D. The control terminal of the sixth switch K6 is electrically connected to the second communication voltage CC2_SRC_CP. When the sixth switch K6 is in the on state, the voltage VD of the second communication voltage CC2_SRC_CP and the fourth internal node D satisfies: CC2_SRC_CP - VD ≥ Vth4', where Vth4' is the threshold voltage of the sixth switch K6. Obviously, VD ≤ CC2_SRC_CP - Vth4'. Taking CC2_SRC_CP - Vth4' as the fourth voltage threshold Vth4, that is, Vth4 = CC2_SRC_CP - Vth4', then VD ≤ Vth4.

[0068] When the second communication pin CC2_PAD is short-circuited with the bus power supply pin VBUS, the sixth switch K6 is in the on state, and the voltage VD of the fourth internal node D still satisfies: VD≤Vth4. Thus, the voltage VD of the fourth internal node D can be limited to be less than or equal to the fourth voltage threshold Vth4.

[0069] In summary, when the first communication pin CC1_PAD and the bus power supply VBUS pin are short-circuited, and / or when the second communication pin CC2_PAD and the bus power supply VBUS pin are short-circuited, the interface circuit 100 is connected to the high-voltage charging voltage. At this time, the voltage VA of the first internal node A is less than or equal to the first voltage threshold Vth1, the voltage VB of the second internal node B is less than or equal to the second voltage threshold Vth2, the voltage VC of the third internal node C is less than or equal to the third voltage threshold Vth3, and the voltage VD of the fourth internal node D is less than or equal to the fourth voltage threshold Vth4. This reduces the voltage of the internal nodes in the interface circuit 100, preventing damage to the interface circuit 100 from the high-voltage short circuit, thus achieving high-voltage short-circuit protection.

[0070] It should be noted that the interface circuit 100 provided in this application embodiment may be a Type-C interface circuit, a PD interface circuit, or other types of interface circuits. This application embodiment does not impose specific limitations on this.

[0071] In this embodiment, the interface circuit includes a first protection branch and a second protection branch. The first end of both the first and second protection branches is electrically connected to a positive power supply voltage. The second end of the first protection branch is electrically connected to a first communication pin, and the second end of the second protection branch is electrically connected to a second communication pin. The first protection branch can limit the voltage of the first internal node to less than or equal to a first voltage threshold and the voltage of the second internal node to less than or equal to a second voltage threshold when the first communication pin is short-circuited to the bus power supply VBUS pin. The second protection branch can limit the voltage of the third internal node to less than or equal to a third voltage threshold and the voltage of the fourth internal node to less than or equal to a fourth voltage threshold when the second communication pin is short-circuited to the bus power supply VBUS pin. Thus, when the communication pin is short-circuited to the bus power supply VBUS pin, i.e., when the interface circuit is connected to the high-voltage charging voltage, the voltage of the internal nodes in the interface circuit can be reduced, preventing damage to the interface circuit from the high-voltage short circuit, thereby achieving high-voltage short-circuit protection.

[0072] In some embodiments, the first protection branch 110 is further configured to conduct the positive power supply voltage VDD and the first communication pin CC1_PAD under the action of the first power supply voltage VCONN CC1_VCONN_CP; the second protection branch 120 is further configured to conduct the positive power supply voltage VDD and the second communication pin CC2_PAD under the action of the second power supply voltage VCONN CC2_VCONN_CP.

[0073] For example, if the first power supply voltage VCONN CC1_VCONN_CP is pulled high to the output voltage V_CPOUT, both the first switch K1 and the second switch K2 are turned on. Therefore, the positive power supply voltage VDD and the first communication pin CC1_PAD can be connected, thus shorting the positive power supply voltage VDD to the first communication pin CC1_PAD and realizing the VCONN output function. For example, if the first switch K1 is a high-voltage MOSFET and the second switch K2 is a low-voltage MOSFET, a smaller VCONN path on-resistance can be achieved.

[0074] If the second power supply voltage VCONN CC2_VCONN_CP is pulled high to the output voltage V_CPOUT, both the fourth switch K4 and the fifth switch K5 will be turned on. Therefore, the positive power supply voltage VDD and the second communication pin CC2_PAD can be turned on, effectively shorting the positive power supply voltage VDD to the second communication pin CC2_PAD, thus realizing the VCONN output function. For example, if the fourth switch K4 is a high-voltage MOSFET and the fifth switch K5 is a low-voltage MOSFET, a smaller VCONN path on-resistance can be achieved.

[0075] In this embodiment, the first protection branch can conduct the positive power supply voltage and the first communication pin under the action of the first power supply voltage VCONN; the second protection branch can conduct the positive power supply voltage and the second communication pin under the action of the second power supply voltage VCONN. In this way, the positive power supply voltage VDD can be shorted to the communication pin to realize the VCONN output function.

[0076] In some embodiments, Figure 3 This is a schematic diagram of another interface circuit provided in an embodiment of this application. Figure 3 for Figure 2 Based on the embodiment shown, the interface circuit 100 further includes a first current source Is1 and a second current source Is2.

[0077] The positive terminals of the first current source Is1 and the second current source Is2 are electrically connected to the positive voltage VDD of the power supply. The negative terminal of the first current source Is1 is electrically connected to the first terminal of the third switch K3, and the negative terminal of the second current source Is2 is electrically connected to the first terminal of the sixth switch K6.

[0078] The first protection branch 110 is also used to conduct the negative terminal of the first current source Is1 and the first communication pin CC1_PAD under the action of the first communication voltage CC1_SRC_CP; the second protection branch 120 is also used to conduct the negative terminal of the second current source Is2 and the second communication pin CC2_PAD under the action of the second communication voltage CC2_SRC_CP.

[0079] For example, such as Figure 3 As shown, the positive voltage VDD of the power supply is electrically connected to the positive terminal of the first current source Is1 and the positive terminal of the second current source Is2. Under the action of the positive voltage VDD, the first current source Is1 generates a first current I_SRC_CC1 and outputs it based on the negative terminal of the first current source Is1. The second current source Is2 generates a second current I_SRC_CC2 and outputs it based on the negative terminal of the second current source Is2.

[0080] If the first communication voltage CC1_SRC_CP is pulled high to the output voltage V_CPOUT, the third switch K3 is in the on state. Therefore, the negative terminal of the first current source Is1 and the first communication pin CC1_PAD can be turned on, that is, the first current I_SRC_CC1 can be output to the first communication pin CC1_PAD, achieving the purpose of pull-up and realizing the Type-C handshake process. If the second communication voltage CC2_SRC_CP is pulled high to the output voltage V_CPOUT, the sixth switch K6 is in the on state. Therefore, the negative terminal of the second current source Is2 and the second communication pin CC2_PAD can be turned on, that is, the second current I_SRC_CC2 can be output to the second communication pin CC2_PAD, achieving the purpose of pull-up and realizing the Type-C handshake process.

[0081] In this embodiment of the application, the interface circuit further includes a first current source and a second current source. The positive terminals of the first and second current sources are both electrically connected to the positive voltage of the power supply. The negative terminal of the first current source is electrically connected to the first terminal of the third switching transistor, and the negative terminal of the second current source is electrically connected to the first terminal of the sixth switching transistor. The first protection branch can conduct the negative terminal of the first current source and the first communication pin under the action of the first communication voltage. The second protection branch can conduct the negative terminal of the second current source and the second communication pin under the action of the second communication voltage. In this way, the current generated by the current source can be output to the communication pin to realize the Type-C handshake process.

[0082] In some embodiments, Figure 4 This is a schematic diagram of another interface circuit provided in an embodiment of this application, as shown below. Figure 4 As shown, the interface circuit 100 also includes: a first control branch 130 and a second control branch 140.

[0083] Specifically, the first terminal of the first control branch 130 and the first terminal of the second control branch 140 are both electrically connected to the output voltage V_CPOUT. The second terminals of the first control branch 130 and the second terminals of the second control branch 140 are both grounded. The third terminal of the first control branch 130 is electrically connected to the control terminal of the second switch K2. The third terminal of the second control branch 140 is electrically connected to the control terminal of the fifth switch K5. The control terminal of the first control branch 130 is electrically connected to the first power supply VCONN enable signal CC1_VCONN_EN. The control terminal of the second control branch 140 is electrically connected to the second power supply VCONN enable signal CC2_VCONN_EN.

[0084] The first control branch 130 is used to turn on the control terminal and output voltage V_CPOUT of the second switch K2, or to connect the control terminal of the second switch K2 to ground, under the action of the first power supply VCONN enable signal CC1_VCONN_EN; the second control branch 140 is used to turn on the control terminal and output voltage V_CPOUT of the fifth switch K5, or to connect the control terminal of the fifth switch K5 to ground, under the action of the second power supply VCONN enable signal CC2_VCONN_EN.

[0085] For example, Figure 5 This is a schematic diagram of another interface circuit provided in an embodiment of this application, as shown below. Figure 5 for Figure 4 Based on the embodiment shown, the first control branch 130 includes: a first control switch S1, a second control switch S2, a first pull-up resistor Ra1, a first pull-down resistor Rb1, and a first clamping diode D1.

[0086] Specifically, the first terminal of the first control switch S1, the first terminal of the first pull-up resistor Ra1, and the cathode of the first clamping diode D1 are all electrically connected to the output voltage V_CPOUT. The second terminal of the first pull-up resistor Ra1 is electrically connected to the anode of the first clamping diode D1, the control terminal of the first control switch S1, and the first terminal of the second control switch S2. The second terminal of the first control switch S1 is electrically connected to the first terminal of the first pull-down resistor Rb1 and the control terminal of the second switch K2. The second terminal of the first pull-down resistor Rb1 and the second terminal of the second control switch S2 are both grounded. The control terminal of the second control switch S2 is electrically connected to the first power supply VCONN enable signal CC1_VCONN_EN.

[0087] If the first power supply VCONN enable signal CC1_VCONN_EN is low, under the action of the first power supply VCONN enable signal CC1_VCONN_EN, the first terminal and the second terminal of the second control switch S2 are disconnected. Since the first terminal of the second control switch S2 is electrically connected to the control terminal of the first control switch S1, and the second terminal of the second control switch S2 is grounded, the control terminal of the first control switch S1 is disconnected from ground. The control terminal of the first control switch S1 is connected to the output voltage V_CPOUT power supply through the first pull-up resistor Ra1, that is, the voltage of the control terminal of the first control switch S1 is pulled up to the output voltage V_CPOUT. Under the action of the output voltage V_CPOUT, the first terminal and the second terminal of the first control switch S1 are disconnected.

[0088] The second terminal of the first control switch S1 is connected to ground through the first pull-down resistor Rb1, and the second terminal of the first control switch S1 is electrically connected to the control terminal of the second switch K2, that is, the control terminal of the second switch K2 is connected to ground through the first pull-down resistor Rb1. Thus, the voltage CC1_VCONN_CP of the first power supply VCONN is pulled down to ground by the first pull-down resistor Rb1. At this time, both the first switch K1 and the second switch K2 are in the off state.

[0089] If the first power supply VCONN enable signal CC1_VCONN_EN is high, under the action of the first power supply VCONN enable signal CC1_VCONN_EN, the first and second terminals of the second control switch S2 are connected, and the control terminal of the first control switch S1 is connected to ground, that is, the voltage of the control terminal of the first control switch S1 is pulled down to ground. At this time, the first and second terminals of the first control switch S1 are connected, and the second terminal of the first control switch S1 is connected to the output voltage V_CPOUT, that is, the control terminal of the second switch K2 is connected to the output voltage V_CPOUT. Therefore, the voltage CC1_VCONN_CP of the first power supply VCONN is pulled high to the output voltage V_CPOUT, and both the first and second switches K1 and K2 are in the on state.

[0090] At this time, the first voltage threshold Vth1 can be V_CPOUT-Vth1'. If the first communication pin CC1_PAD is short-circuited with the bus power supply VBUS pin, the voltage VA of the first internal node A is less than or equal to V_CPOUT-Vth1'.

[0091] See also Figure 5 The second control branch includes: a third control switch S3, a fourth control switch S4, a second pull-up resistor Ra2, a second pull-down resistor Rb2, and a second clamping diode D2.

[0092] Specifically, the first terminal of the third control switch S3, the first terminal of the second pull-up resistor Ra2, and the cathode of the second clamping diode D2 are all electrically connected to the output voltage V_CPOUT. The second terminal of the second pull-up resistor Ra2 is electrically connected to the anode of the second clamping diode D2, the control terminal of the third control switch S3, and the first terminal of the fourth control switch S4. The second terminal of the third control switch S3 is electrically connected to the first terminal of the second pull-down resistor Rb2 and the control terminal of the fifth switch K5. The second terminals of the second pull-down resistor Rb2 and the second terminal of the fourth control switch S4 are both grounded. The control terminal of the fourth control switch S4 is electrically connected to the enable signal CC2_VCONN_EN of the second power supply VCONN.

[0093] If the second power supply VCONN enable signal CC2_VCONN_EN is low, the first and second terminals of the fourth control switch S4 are disconnected under the action of the second power supply VCONN enable signal CC2_VCONN_EN. Since the first terminal of the fourth control switch S4 is electrically connected to the control terminal of the third control switch S3, and the second terminal of the fourth control switch S4 is grounded, the control terminal of the third control switch S3 is disconnected from ground. The control terminal of the third control switch S3 is connected to the output voltage V_CPOUT power supply through the second pull-up resistor Ra2, that is, the voltage of the control terminal of the third control switch S3 is pulled up to the output voltage V_CPOUT. Under the action of the output voltage V_CPOUT, the first and second terminals of the third control switch S3 are disconnected.

[0094] The second terminal of the third control switch S3 is connected to ground through the second pull-down resistor Rb2, and the second terminal of the third control switch S3 is electrically connected to the control terminal of the fifth switch K5, that is, the control terminal of the fifth switch K5 is connected to ground through the second pull-down resistor Rb2. Thus, the voltage CC2_VCONN_CP of the second power supply VCONN is pulled down to ground by the second pull-down resistor Rb2. At this time, both the fourth switch K4 and the fifth switch K5 are in the off state.

[0095] If the enable signal CC2_VCONN_EN for the second power supply VCONN is high, under its influence, the first and second terminals of the fourth control switch S4 are connected, and the control terminal of the third control switch S3 is connected to ground, meaning the voltage at the control terminal of the third control switch S3 is pulled down to ground. At this time, the first and second terminals of the third control switch S3 are connected, and the second terminal of the third control switch S3 is connected to the output voltage V_CPOUT, meaning the control terminal of the fifth switch K5 is connected to the output voltage V_CPOUT. Therefore, the voltage CC2_VCONN_CP of the second power supply VCONN is pulled high to the output voltage V_CPOUT, and both the fourth and fifth switches K4 and K5 are in the ON state.

[0096] At this point, the third voltage threshold Vth3 can be V_CPOUT-Vth3'. If the second communication pin CC2_PAD is short-circuited with the bus power supply VBUS pin, the voltage VC of the third internal node C is less than or equal to V_CPOUT-Vth3'. Specifically, if the second switch K2 and the fifth switch K5 have the same specifications, then Vth3' = Vth1', meaning the third voltage threshold Vth3 is the same as the first voltage threshold Vth1, and Vth1 = Vth3 = V_CPOUT-Vth1'. In other words, when the second communication pin CC2_PAD is short-circuited with the bus power supply VBUS pin, the voltage VC of the third internal node C is less than or equal to V_CPOUT-Vth1', and when the first communication pin CC1_PAD is short-circuited with the bus power supply VBUS pin, the voltage VA of the first internal node A is also less than or equal to V_CPOUT-Vth1'.

[0097] In some embodiments, Figure 6 This is a schematic diagram of another interface circuit provided in an embodiment of this application, as shown below. Figure 6 As shown, the interface circuit 100 also includes a third control branch 150 and a fourth control branch 160.

[0098] Specifically, the first terminal of the third control branch 150 and the first terminal of the fourth control branch 160 are both electrically connected to the output voltage V_CPOUT. The second terminals of the third control branch 150 and the fourth control branch 160 are both grounded. The third terminal of the third control branch 150 is electrically connected to the control terminal of the third switch K3. The third terminal of the fourth control branch 160 is electrically connected to the control terminal of the sixth switch K6. The control terminal of the third control branch 150 is electrically connected to the first communication enable signal CC1_SRC_EN. The control terminal of the fourth control branch 160 is electrically connected to the second communication enable signal CC2_SRC_EN.

[0099] The third control branch 150 is used to turn on the control terminal and output voltage V_CPOUT of the third switch K3, or to turn on the control terminal of the third switch K3 and ground, under the action of the first communication enable signal CC1_SRC_EN; the fourth control branch 160 is used to turn on the control terminal and output voltage V_CPOUT of the sixth switch K6, or to turn on the control terminal of the sixth switch K6 and ground, under the action of the second communication enable signal CC2_SRC_EN.

[0100] For example, Figure 7 This is a schematic diagram of another interface circuit provided in an embodiment of this application. Figure 7 for Figure 6 Based on the embodiment shown, the third control branch 150 includes: a fifth control switch S5, a sixth control switch S6, a third pull-up resistor Ra3, a third pull-down resistor Rb3, and a third clamping diode D3.

[0101] Specifically, the first terminal of the fifth control switch S5, the first terminal of the third pull-up resistor Ra3, and the cathode of the third clamping diode D3 are all electrically connected to the output voltage V_CPOUT. The second terminal of the third pull-up resistor Ra3 is electrically connected to the anode of the third clamping diode D3, the control terminal of the fifth control switch S5, and the first terminal of the sixth control switch S6. The second terminal of the fifth control switch S5 is electrically connected to the first terminal of the third pull-down resistor Rb3 and the control terminal of the third switching transistor K3. The second terminals of the third pull-down resistor Rb3 and the second terminal of the sixth control switch S6 are both grounded. The control terminal of the sixth control switch S6 is electrically connected to the first communication enable signal CC1_SRC_EN.

[0102] If the first communication enable signal CC1_SRC_EN is low, the first and second terminals of the sixth control switch S6 are disconnected under its influence. Since the first terminal of the sixth control switch S6 is electrically connected to the control terminal of the fifth control switch S5, and the second terminal of the sixth control switch S6 is grounded, the control terminal of the fifth control switch S5 is disconnected from ground. The control terminal of the fifth control switch S5 is connected to the output voltage V_CPOUT power supply through the third pull-up resistor Ra3, meaning the voltage at the control terminal of the fifth control switch S5 is pulled high to the output voltage V_CPOUT. Under the influence of the output voltage V_CPOUT, the first and second terminals of the fifth control switch S5 are disconnected.

[0103] The second terminal of the fifth control switch S5 is connected to ground through the third pull-down resistor Rb3, and the second terminal of the fifth control switch S5 is electrically connected to the control terminal of the third switch K3, that is, the control terminal of the third switch K3 is connected to ground through the third pull-down resistor Rb3. Thus, the first communication voltage CC1_SRC_CP is pulled down to ground by the third pull-down resistor Rb3, and at this time, the third switch K3 is in the off state.

[0104] If the first communication enable signal CC1_SRC_EN is high, under its influence, the first and second terminals of the sixth control switch S6 are connected, and the control terminal of the fifth control switch S5 is connected to ground, meaning the voltage at the control terminal of the fifth control switch S5 is pulled down to ground. At this time, the first and second terminals of the fifth control switch S5 are connected, and the second terminal of the fifth control switch S5 is connected to the output voltage V_CPOUT, meaning the control terminal of the third switch K3 is connected to the output voltage V_CPOUT. Therefore, the first communication voltage CC1_SRC_CP is pulled high to the output voltage V_CPOUT, and the third switch K3 is in the ON state.

[0105] At this time, the second voltage threshold Vth2 can be V_CPOUT-Vth2'. If the first communication pin CC1_PAD is short-circuited with the bus power supply VBUS pin, the voltage VB of the second internal node B is less than or equal to V_CPOUT-Vth2'. Specifically, if the second switch K2, the third switch K3, and the fifth switch K5 have the same specifications, then Vth2' = Vth1' = Vth3', meaning the second voltage threshold Vth2, the first voltage threshold Vth1, and the third voltage threshold Vth3 are all the same, and Vth1 = Vth2 = Vth3 = V_CPOUT-Vth1'. In other words, when the first communication pin CC1_PAD is short-circuited with the bus power supply VBUS pin, the voltage VA of the first internal node A and the voltage VB of the second internal node B are both less than or equal to V_CPOUT-Vth1'. When the second communication pin CC2_PAD is short-circuited with the bus power supply VBUS pin, the voltage VC of the third internal node C is also less than or equal to V_CPOUT-Vth1'.

[0106] See also Figure 7 The fourth control branch 160 includes: a seventh control switch S7, an eighth control switch S8, a fourth pull-up resistor Ra4, a fourth pull-down resistor Rb4, and a fourth clamping diode D4.

[0107] Specifically, the first terminal of the seventh control switch S7, the first terminal of the fourth pull-up resistor Ra4, and the cathode of the fourth clamping diode D4 are all electrically connected to the output voltage V_CPOUT. The second terminal of the fourth pull-up resistor Ra4 is electrically connected to the anode of the fourth clamping diode D4, the control terminal of the seventh control switch S7, and the first terminal of the eighth control switch S8. The second terminal of the seventh control switch S7 is electrically connected to the first terminal of the fourth pull-down resistor Rb4 and the control terminal of the sixth switch K6. The second terminals of the fourth pull-down resistor Rb4 and the second terminal of the eighth control switch S8 are both grounded. The control terminal of the eighth control switch S8 is electrically connected to the second communication enable signal CC2_SRC_EN.

[0108] If the second communication enable signal CC2_SRC_EN is low, the first and second terminals of the eighth control switch S8 will be disconnected under its influence. Since the first terminal of the eighth control switch S8 is electrically connected to the control terminal of the seventh control switch S7, and the second terminal of the eighth control switch S8 is grounded, the control terminal of the seventh control switch S7 will be disconnected from ground. The control terminal of the seventh control switch S7 will be connected to the output voltage V_CPOUT power supply through the fourth pull-up resistor Ra4, meaning the voltage at the control terminal of the seventh control switch S7 will be pulled high to the output voltage V_CPOUT. Under the influence of the output voltage V_CPOUT, the first and second terminals of the seventh control switch S7 will be disconnected.

[0109] The second terminal of the seventh control switch S7 is connected to ground through the fourth pull-down resistor Rb4, and the second terminal of the seventh control switch S7 is electrically connected to the control terminal of the sixth switch K6, that is, the control terminal of the sixth switch K6 is connected to ground through the fourth pull-down resistor Rb4. Thus, the second communication voltage CC2_SRC_CP is pulled down to ground by the fourth pull-down resistor Rb4, and at this time, the sixth switch K6 is in the off state.

[0110] If the second communication enable signal CC2_SRC_EN is high, under its influence, the first and second terminals of the eighth control switch S8 are connected, and the control terminal of the seventh control switch S7 is connected to ground, meaning the voltage at the control terminal of the seventh control switch S7 is pulled down to ground. At this time, the first and second terminals of the seventh control switch S7 are connected, and the second terminal of the seventh control switch S7 is connected to the output voltage V_CPOUT, meaning the control terminal of the sixth switch K6 is connected to the output voltage V_CPOUT. Therefore, the second communication voltage CC2_SRC_CP is pulled high to the output voltage V_CPOUT, and the sixth switch K6 is in the ON state.

[0111] At this time, the fourth voltage threshold Vth4 can be V_CPOUT-Vth4'. If the second communication pin CC1_PAD is short-circuited with the bus power supply pin VBUS, the voltage VD of the fourth internal node D is less than or equal to V_CPOUT-Vth4'. Specifically, if the second switch K2, the third switch K3, the fifth switch K5, and the sixth switch K6 have the same specifications, then Vth2' = Vth1' = Vth3' = Vth4', meaning the second voltage threshold Vth2, the first voltage threshold Vth1, the third voltage threshold Vth3, and the fourth voltage threshold Vth4 are all the same, and Vth1 = Vth2 = Vth3 = Vth4 = V_CPOUT-Vth1'. In other words, when the first communication pin CC1_PAD is short-circuited with the bus power supply VBUS pin, the voltage VA of the first internal node A and the voltage VB of the second internal node B are both less than or equal to V_CPOUT-Vth1'. When the second communication pin CC2_PAD is short-circuited with the bus power supply VBUS pin, the voltage VC of the third internal node C and the voltage VD of the fourth internal node D are also less than or equal to V_CPOUT-Vth1'.

[0112] In some embodiments, the interface circuit 100 further includes a charge pump branch, the input terminal of which is electrically connected to the input voltage V_CPIN, and the output terminal of which is electrically connected to the output voltage V_CPOUT, wherein V_CPOUT = 2 * V_CPIN, and the V_CPIN voltage can be determined according to the withstand voltage of the first internal node A, the second internal node B, the third internal node C, and the fourth internal node D.

[0113] This application also provides an interface device, including the interface circuit provided in any of the above embodiments.

[0114] For example, the interface device may be a Type-C USB interface, a Type-C to Type-A interface adapter, a Lightning to Type-C interface adapter, or an adapter for any other two types of interfaces. This application embodiment does not impose specific limitations on this.

[0115] The interface device provided in this application includes the interface circuit provided in any embodiment, and has the same functional modules and beneficial effects as the interface circuit, which will not be described in detail here.

[0116] The above-disclosed embodiments are merely specific examples of this application. However, the embodiments of this application are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of this application.

[0117] The term "comprising" as used in this application does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims listing several means, several units of these means may be embodied by the same item of hardware. The use of "first," "second," and "third," etc., does not indicate any order and should be interpreted as names. Unless otherwise specified, the steps in the above embodiments should not be construed as limiting the order of execution.

[0118] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An interface circuit, characterized by The application relates to a protection circuit for a communication device, which comprises: a first protection branch and a second protection branch; a first end of the first protection branch and a first end of the second protection branch are electrically connected to a positive voltage of a power supply, a second end of the first protection branch is electrically connected to a first communication pin, and a second end of the second protection branch is electrically connected to a second communication pin; the first protection branch is used for limiting a voltage of a first internal node to be less than or equal to a first voltage threshold and limiting a voltage of a second internal node to be less than or equal to a second voltage threshold when the first communication pin is short-circuited with a bus power supply VBUS pin; the second protection branch is used for limiting a voltage of a third internal node to be less than or equal to a third voltage threshold and limiting a voltage of a fourth internal node to be less than or equal to a fourth voltage threshold when the second communication pin is short-circuited with the bus power supply VBUS pin; the first protection branch comprises a first switch tube, a second switch tube and a third switch tube; a first end of the first switch tube and a first end of the third switch tube are electrically connected to the positive voltage of the power supply, a second end of the first switch tube is electrically connected to a first end of the second switch tube, a control end of the first switch tube and a control end of the second switch tube are electrically connected to a first power supply VCONN voltage, a second end of the second switch tube and a second end of the third switch tube are electrically connected to the first communication pin, and a control end of the third switch tube is electrically connected to a first communication voltage.

2. The interface circuit of claim 1, wherein, the second protection branch comprises a fourth switch tube, a fifth switch tube and a sixth switch tube; a first end of the fourth switch tube and a first end of the sixth switch tube are electrically connected to the positive voltage of the power supply, a second end of the fourth switch tube is electrically connected to a first end of the fifth switch tube, a control end of the fourth switch tube and a control end of the fifth switch tube are electrically connected to a second power supply VCONN voltage, a second end of the fifth switch tube and a second end of the sixth switch tube are electrically connected to the second communication pin, and a control end of the sixth switch tube is electrically connected to a second communication voltage.

3. The interface circuit of claim 2, wherein, the first protection branch is further used for conducting the positive voltage of the power supply and the first communication pin under the action of the first power supply VCONN voltage; the second protection branch is further used for conducting the positive voltage of the power supply and the second communication pin under the action of the second power supply VCONN voltage.

4. The interface circuit of claim 2, wherein, the application further comprises a first current source and a second current source; a positive end of the first current source and a positive end of the second current source are electrically connected to the positive voltage of the power supply, a negative end of the first current source is electrically connected to a first end of the third switch tube, and a negative end of the second current source is electrically connected to a first end of the sixth switch tube; the first protection branch is further used for conducting the negative end of the first current source and the first communication pin under the action of the first communication voltage; the second protection branch is further used for conducting the negative end of the second current source and the second communication pin under the action of the second communication voltage.

5. The interface circuit of claim 2, wherein, the application further comprises a first control branch and a second control branch; The first end of the first control branch and the first end of the second control branch are electrically connected to an output voltage, the second end of the first control branch and the second end of the second control branch are grounded, the third end of the first control branch is electrically connected to the control end of the second switch tube, the third end of the second control branch is electrically connected to the control end of the fifth switch tube, the control end of the first control branch is electrically connected to a first power supply VCONN enable signal, and the control end of the second control branch is electrically connected to a second power supply VCONN enable signal. The first control branch is configured to, under the action of the first power supply VCONN enable signal, conduct the control end of the second switch tube and the output voltage or conduct the control end of the second switch tube and the ground. The second control branch is configured to, under the action of the second power supply VCONN enable signal, conduct the control end of the fifth switch tube and the output voltage or conduct the control end of the fifth switch tube and the ground.

6. The interface circuit of claim 5, wherein, The first control branch includes a first control switch, a second control switch, a first pull-up resistor, a first pull-down resistor, and a first clamping diode. The first end of the first control switch, the first end of the first pull-up resistor, and the cathode of the first clamping diode are electrically connected to the output voltage, the second end of the first pull-up resistor is electrically connected to the anode of the first clamping diode, the control end of the first control switch, and the first end of the second control switch, the second end of the first control switch is electrically connected to the first end of the first pull-down resistor and the control end of the second switch tube, the second end of the first pull-down resistor and the second end of the second control switch are grounded, and the control end of the second control switch is electrically connected to the first power supply VCONN enable signal.

7. The interface circuit of claim 5, wherein, The second control branch includes a third control switch, a fourth control switch, a second pull-up resistor, a second pull-down resistor, and a second clamping diode. The first end of the third control switch, the first end of the second pull-up resistor, and the cathode of the second clamping diode are electrically connected to the output voltage, the second end of the second pull-up resistor is electrically connected to the anode of the second clamping diode, the control end of the third control switch, and the first end of the fourth control switch, the second end of the third control switch is electrically connected to the first end of the second pull-down resistor and the control end of the fifth switch tube, the second end of the second pull-down resistor and the second end of the fourth control switch are grounded, and the control end of the fourth control switch is electrically connected to the second power supply VCONN enable signal.

8. The interface circuit of claim 2 or 5, wherein, The third control branch and the fourth control branch are further included. The first end of the third control branch and the first end of the fourth control branch are electrically connected to an output voltage, the second end of the third control branch and the second end of the fourth control branch are grounded, the third end of the third control branch is electrically connected to the control end of the third switch tube, the third end of the fourth control branch is electrically connected to the control end of the sixth switch tube, the control end of the third control branch is electrically connected to a first communication enable signal, and the control end of the fourth control branch is electrically connected to a second communication enable signal. The third control branch is configured to, under the action of the first communication enable signal, connect the control end of the third switch tube to the output voltage or connect the control end of the third switch tube to the ground. The fourth control branch is configured to, under the action of the second communication enable signal, connect the control end of the sixth switch tube to the output voltage or connect the control end of the sixth switch tube to the ground.

9. The interface circuit of claim 8, wherein, The third control branch comprises a fifth control switch, a sixth control switch, a third pull-up resistor, a third pull-down resistor, and a third clamping diode. The first end of the fifth control switch, the first end of the third pull-up resistor, and the cathode of the third clamping diode are electrically connected to the output voltage, the second end of the third pull-up resistor is electrically connected to the anode of the third clamping diode, the control end of the fifth control switch, and the first end of the sixth control switch, the second end of the fifth control switch is electrically connected to the first end of the third pull-down resistor and the control end of the third switch tube, the second end of the third pull-down resistor and the second end of the sixth control switch are grounded, and the control end of the sixth control switch is electrically connected to the first communication enable signal.

10. The interface circuit of claim 8, wherein, The fourth control branch comprises a seventh control switch, an eighth control switch, a fourth pull-up resistor, a fourth pull-down resistor, and a fourth clamping diode. The first end of the seventh control switch, the first end of the fourth pull-up resistor, and the cathode of the fourth clamping diode are electrically connected to the output voltage, the second end of the fourth pull-up resistor is electrically connected to the anode of the fourth clamping diode, the control end of the seventh control switch, and the first end of the eighth control switch, the second end of the seventh control switch is electrically connected to the first end of the fourth pull-down resistor and the control end of the sixth switch tube, the second end of the fourth pull-down resistor and the second end of the eighth control switch are grounded, and the control end of the eighth control switch is electrically connected to the second communication enable signal.

11. An interface device, comprising: The interface circuit comprises any one of claims 1-10.

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