Interface conversion circuit and interface converter for USB-C to Lightning
By using a CC switching circuit composed of discrete electronic devices, CC signal transmission between the USB-C interface and the Lightning interface is realized, which solves the high cost and high power consumption problems caused by the integrated chip solution in the prior art, and achieves the goals of miniaturization and low power consumption.
Patent Information
- Application Number
- CN202411881232.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-03-11
AI Technical Summary
The existing USB-C to Lightning converters adopt an integrated chip solution, resulting in high product prices, high power consumption, and difficulty in optimizing performance.
Using a CC switching circuit composed of discrete electronic devices, the first and second switching units are accurately controlled to achieve a stable connection between the CC signal of the USB-C interface and the CC signal of the Lightning interface.
On the premise of meeting the MFi certification requirements, production costs and power consumption are reduced, and the goals of miniaturization and low power consumption are achieved.
Smart Images
Figure CN119597695A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of interface switching, and in particular relates to an interface conversion circuit. Background Art
[0002] With the diversified development of electronic device interfaces, users usually need to charge and transfer data between different devices. For example, Apple’s older devices (such as iPhone and iPad) use the Lightning interface, while newer devices (such as iPhone 15, some iPads and MacBooks) gradually adopt the USB-C interface. For Apple device users, due to their large user base and high market share, there is also a great demand for USB-C to Lightning adapters.
[0003] However, most of the USB-C to Lightning converters on the market currently use integrated chip solutions to implement the CC signal switching of the interface. Their complex internal structure and package size lead to a relatively high overall price of the product. In addition, due to the high power consumption characteristics of the integrated chip, its actual static current is close to the upper limit required by the MFi certification (MFi certification requires a static current of ≤1.25 mA). This not only increases the complexity of circuit design, but also limits the space for further optimizing product performance. Therefore, how to optimize the CC switching circuit design to reduce production costs, reduce power consumption and achieve smaller and lighter products while meeting the MFi certification requirements is a problem that needs to be urgently solved in the existing technology. Summary of the invention
[0004] In order to solve the common problems in the prior art, the present invention provides an interface conversion circuit, which adopts a CC switching circuit composed of discrete electronic devices to realize the control of data signal transmission and support for fast charging protocols such as PD and DCP.
[0005] In a first aspect, the present invention provides an interface conversion circuit, comprising:
[0006] A first switch unit, a first end of which is connected to the CC1 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC1 pin of the USB-C interface and the CC pin of the Lightning interface;
[0007] A second switch unit, a first end of which is connected to the CC2 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC2 pin of the USB-C interface and the CC pin of the Lightning interface;
[0008] A cc switching circuit, wherein a first control end thereof is connected to a controlled end of the first switch unit, a second control end thereof is connected to a controlled end of the second switch unit, and an input end thereof is connected to a CC1 pin and a CC2 pin of the USB-C interface, and the cc switching circuit is used to control the transmission of a signal between the first switch unit and the Lightning interface;
[0009] Alternatively, it is used to control the transmission of a signal between the second switch unit and the Lightning interface.
[0010] Furthermore, the CC switching circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first switch tube and a second switch tube. The CC1 pin of the USB-C interface is connected to the base of the first switch tube through the first resistor, and is respectively connected to the collector of the second switch tube and the controlled end of the first switch unit through the third resistor. The emitter of the first switch tube is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the first switch tube and the sixth resistor through the second resistor. The CC2 pin of the USB-C interface is connected to the base of the second switch tube through the fourth resistor, and is respectively connected to the collector of the first switch tube and the controlled end of the second switch unit through the sixth resistor. The emitter of the second switch tube is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the second switch tube and the third resistor through the fifth resistor.
[0011] Further, the first switch unit includes a third switch tube, the second switch unit includes a fourth switch tube, the gate of the third switch tube is connected to the controlled end of the first switch unit, the source is connected to the CC1 pin of the USB-C interface, and the drain is connected to the CC pin of the Lighting interface, the gate of the fourth switch tube Q2 is connected to the controlled end of the second switch unit, the source is connected to the CC2 pin of the USB-C interface, and the drain is connected to the CC pin of the Lighting interface.
[0012] Furthermore, the first switch unit also includes a first diode, and the second switch unit also includes a second diode, the anode of the first diode is connected to the source of the third switch tube, and the cathode is connected to the drain of the third switch tube, and the anode of the second diode is connected to the source of the fourth switch tube, and the cathode is connected to the drain of the fourth switch tube.
[0013] Furthermore, the first switch tube and the second switch tube are both NPN transistors, the third switch tube and the fourth switch tube are both NMOS tubes, and the first diode and the second diode are both diodes.
[0014] Furthermore, the resistance values of the first resistor and the second resistor are equal, and the resistance values of the third resistor and the fourth resistor are equal.
[0015] Furthermore, the first switch tube and the second switch tube are integrated MOS tubes in a two-in-one package, and the third switch tube and the fourth switch tube are integrated triodes in a two-in-one package.
[0016] Furthermore, the first diode and the second diode are integrated diodes in a two-in-one package.
[0017] In a second aspect, the present invention also provides an interface converter, comprising at least a USB-C interface, an interface conversion circuit and a Lighting interface, wherein the USB-C interface is electrically connected to the interface conversion circuit and the Lighting interface respectively, and the interface conversion circuit is electrically connected to the Lighting interface, and the interface conversion circuit is the above-mentioned interface conversion circuit.
[0018] The A6 and B6 pins of the USB-C interface are connected to the DP pin of the Lightning interface, and the A7 and B7 pins of the USB-C interface are connected to the DM pin of the Lightning interface.
[0019] The power supply end of the USB-C interface is respectively connected to the A4 pin, B4 pin, A9 pin, B9 pin of the USB-C interface, and the A1 pin, A12 pin, B1 pin, B12 pin, G1 pin, G2 pin, G3 pin, G4 pin of the USB-C interface and connected to the ground end.
[0020] Compared with the prior art, the present invention has the following advantages:
[0021] Compared with the existing integrated chip solutions, the embodiments of the present invention do not require additional integrated chips or specific MFI chips. It only needs to use a cc conversion circuit composed of simple discrete electronic devices to significantly reduce the static current while meeting the requirements of MFi certification, thereby achieving the goals of miniaturization and low power consumption.
[0022] In addition, by respectively controlling the first switch unit and the second switch unit through the CC switching circuit, precise control of the two switch units is achieved, so that the CC1 or CC2 pin of the USB-C interface and the CC pin of the Lightning interface of the entire circuit enter a continuously stable connection state. The embodiment of the present invention abandons the high-cost, high-power integrated chip solution in the prior art, and uses simple and efficient discrete devices to implement the CC signal transmission function, which greatly reduces the production cost and circuit complexity. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1This is the female pinout diagram of the USB-C interface;
[0024] Figure 2 This is the male pin diagram of the Lightnint interface;
[0025] Figure 3 It is a principle block diagram of an interface switching circuit embodiment of the present invention;
[0026] Figure 4 is a circuit schematic diagram of another embodiment of an interface switching circuit of the present invention;
[0027] Figure 5 is a circuit schematic diagram of another interface switching circuit embodiment of the present invention;
[0028] Figure 6 The invention discloses a principle block diagram of an interface converter.
[0029] Reference numerals:
[0030] DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0032] The terms "first", "second" and "third" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of the indicated technical features. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative position relationship or movement between the components in a certain specific posture (as shown in the accompanying drawings); it should be noted that when a component is referred to as "fixed to", "set to", or "connected to" another component, it can be directly on the other component or there can be a central component. When a component is considered to be "connected" to another component, it can be directly connected to another component, or there may be one or more central components in between. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.
[0033] Reference Figure 1The female pin distribution of the USB-C interface includes two rows of symmetrical pins, which are marked as Group A (A1-A12) and Group B (B1-B12), respectively. The pins and functions related to the present invention are described as follows:
[0034] CC1 (A5 pin) and CC2 (B5 pin) are important pins in the USB-C interface for power negotiation (USB Power Delivery, PD) and fast charging protocol identification. The CC switching circuit of the present invention is respectively connected to these two pins to realize the switching and transmission of CC signals.
[0035] VBUS (A4, A9, B4, B9 pins) is a power supply pin, providing a voltage output of 5V to 20V for powering the connected device. In the present invention, the VBUS pin is connected to the control circuit through discrete components to provide an operating voltage for the switch tube.
[0036] D+ (A6 pin, B6 pin) and D- (A7 pin, B7 pin) are connected to the DP and DM pins of the Lightning interface through an interface conversion circuit to support data transmission function.
[0037] GND (A1, A12, B1, B12 pins) is a ground pin used to provide a reference voltage for the circuit.
[0038] It should be noted that, although the above description only mentions the pin distribution of the female head of the USB-C interface, in fact, the design of the present invention is also applicable to the male head of the USB-C interface. The male and female heads of the USB-C interface have the same pin functions and arrangements, but differ in the connection method. Therefore, the cc switching circuit of the present invention can be adapted and signal transmitted at either end between the female head and the male head.
[0039] Reference Figure 2 In the present invention, pin 1 (VBUS) is used to power the device. Pin 1 (VBUS) is connected to the power pin of the Lightning interface through the VBUS pin of the USB-C interface to ensure normal power supply of the device. Pin 2 (DP) is responsible for positive data transmission in the USB2.0 protocol. Pin 3 (DM) is responsible for negative data transmission in the USB 2.0 protocol. Pin 4 (ID) is used for accessory authentication and protocol identification. Pins 5-8 (GND) provide grounding connections to ensure stable operation of the circuit.
[0040] Reference Figure 3 , an embodiment of the present invention provides an interface conversion circuit, comprising:
[0041] A first switch unit 200, a first end of which is connected to the CC1 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC1 pin of the USB-C interface and the CC pin of the Lightning interface;
[0042] A second switch unit 300, a first end of which is connected to the CC2 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC2 pin of the USB-C interface and the CC pin of the Lightning interface;
[0043] The cc switching circuit 100 has a first control end connected to the controlled end of the first switch unit 200, a second control end connected to the controlled end of the second switch unit 300, and an input end connected to the CC1 pin and the CC2 pin of the USB-C interface. The cc switching circuit 100 is used to control the transmission of signals between the first switch unit 200 and the Lightning interface;
[0044] Alternatively, it is used to control the transmission of a signal between the second switch unit 300 and the Lightning interface.
[0045] Compared with the existing integrated chip solutions, the embodiments of the present invention do not require additional integrated chips or specific MFI chips. It only needs to use a cc conversion circuit composed of simple discrete electronic devices to significantly reduce the static current while meeting the requirements of MFi certification, thereby achieving the goals of miniaturization and low power consumption.
[0046] In addition, by respectively controlling the first switch unit and the second switch unit through the CC switching circuit, precise control of the two switch units is achieved, so that the CC1 or CC2 pin of the USB-C interface and the CC pin of the Lightning interface of the entire circuit enter a continuously and stably connected state. This design abandons the high-cost, high-power integrated chip solution in the existing technology, and uses simple and efficient discrete devices to realize the CC signal transmission function, which greatly reduces the production cost and circuit complexity.
[0047] It should be noted that the first end of the first switch unit 200 is a signal input end, which is used to receive the CC1 signal from the USB-C interface. The second end of the first switch unit 200 is a signal output end, which transmits the signal of the CC1 pin to the CC pin of the Lightning interface. The first end of the second switch unit 300 is a signal input end, which receives the CC2 signal from the USB-C interface. The second end of the second switch unit 300 is a signal output end, which transmits the signal of the CC2 pin to the CC pin of the Lightning interface.
[0048] It should also be noted that the first control end of the CC switching circuit 100 is a signal output end for controlling the operation of the first switch unit 200. It turns on or off the controlled end of the first switch unit 200 through a control signal, thereby realizing the CC signal transmission between the CC1 pin of the USB-C interface and the Lightning interface. The controlled end of the first switch unit 200 is an input end for receiving a control signal. When the controlled end receives a signal from the first control end of the CC switching circuit 100, the first switch unit 200 is turned on, and a signal path is established between the CC1 pin of the USB-C interface and the Lightning interface.
[0049] Similarly, the second control end of the CC switching circuit 100 is a signal output end for controlling the operation of the second switch unit 300. It turns on or off the controlled end of the second switch unit 300 through a control signal, thereby realizing CC signal transmission between the CC2 pin of the USB-C interface and the Lightning interface, and the controlled end of the second switch unit 300 is an input end for receiving a control signal. When the controlled end receives a signal from the second control end of the CC switching circuit 100, the second switch unit 300 is turned on, and a signal path is established between the CC2 pin of the USB-C interface and the Lightning interface.
[0050] Reference Figure 4 The embodiment of the present invention provides another interface conversion circuit. Specifically, the CC switching circuit 100 includes a first resistor R7, a second resistor R8, a third resistor R9, a fourth resistor R10, a fifth resistor R11, a sixth resistor R12, a first switch tube Q2 and a second switch tube Q4. The CC1 pin of the USB-C interface is connected to the base of the first switch tube Q2 through the first resistor R7, and is respectively connected to the collector of the second switch tube Q4 and the controlled end of the first switch unit 200 through the third resistor R9. The emitter of the first switch tube Q2 is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the first switch tube Q2 and the sixth resistor R12 through the second resistor R8. The CC2 pin of the USB-C interface is connected to the base of the second switch tube Q4 through the fourth resistor R10, and is respectively connected to the collector of the first switch tube Q2 and the controlled end of the second switch unit 300 through the sixth resistor R12. The emitter of the second switch tube Q4 is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the second switch tube Q4 and the third resistor R9 through the fifth resistor R11.
[0051] Further, the first switch unit 200 includes a third switch tube Q1, and the second switch unit 300 includes a fourth switch tube Q3. The gate of the third switch tube Q1 is connected to the controlled end of the first switch unit 200, the source is connected to the CC1 pin of the USB-C interface, and the drain is connected to the CC pin of the Lightning interface. The gate of the fourth switch tube Q3 is connected to the controlled end of the second switch unit 300, the source is connected to the CC2 pin of the USB-C interface, and the drain is connected to the CC pin of the Lightning interface.
[0052] Specifically, when the CC1 pin of USB-C is connected to the CC channel, due to the voltage divider formed by the diode D4 and the Rd resistor inside the Lightning C94, the Rp resistor on the CC channel works together, so that the host end can recognize that a device is connected and make the VBUS output voltage normal. At this time, the VBUS end provides a bias current to the first switch tube Q2 through the R11 and R9 resistors, so that the first switch tube Q2 is saturated and turned on. After the first switch tube Q2 is turned on, its collector voltage is pulled down, and the base voltage of the second switch tube Q4 of the second control unit is pulled to a very low value through R12, so that the second switch tube Q4 remains in the cut-off state, thereby avoiding competition with the second switch tube Q2. In this state, the third switch tube Q1 is activated, allowing the signal of the CC1 pin to be transmitted to the CC pin of the Lightning interface through the third switch tube Q1, completing the stable connection between the CC1 of USB-C and the CC of Lightning, and realizing the normal negotiation and data communication of the PD protocol.
[0053] Similarly, if the CC2 pin of USB-C is connected to the CC channel, the CC2 pin forms a voltage divider through the diode D5 and the Rd resistor of Lightning C94, so that the host end can recognize the device connection, and VBUS provides bias current to the second switch tube Q4 of the second control unit through R10 and R12, so that the second switch tube Q4 is saturated and turned on, and the first switch tube Q2 is cut off because the base voltage is pulled down. At this time, the fourth switch tube Q3 of the second communication unit is activated, allowing the signal of the CC2 pin to be transmitted to the CC pin of the Lightning interface through Q3, thereby realizing a stable connection between the CC2 of USB-C and the LightningCC.
[0054] This embodiment realizes the mutually exclusive switching between CC1 and CC2 by controlling the conduction and cutoff of Q2 and Q4. At the same time, the voltage is limited by the voltage divider resistor to avoid damage to the MOS tube. The system static current is controlled within the range required by the MFi certification by selecting the appropriate resistance value, ensuring low power consumption and efficient operation of the system.
[0055] In some embodiments, the first switch unit 200 further includes a first diode D4, and the second switch unit 300 further includes a second diode D5, wherein the anode of the first diode D4 is connected to the source of the third switch tube Q1, and the cathode is connected to the drain of the third switch tube Q1, and the anode of the second diode D5 is connected to the source of the fourth switch tube Q3, and the cathode is connected to the drain of the fourth switch tube Q3.
[0056] In the embodiment of the present invention, the first diode D4 and the second diode D5 are provided to achieve unidirectional conduction control of the signal path between the source and drain of the third switch tube Q1 and the fourth switch tube Q3, thereby further improving the stability and reliability of CC signal transmission.
[0057] In some embodiments, the first switch tube Q2 and the second switch tube Q4 use NPN transistors to control the signal transmission of the CC1 and CC2 pins of the USB-C interface respectively; the third switch tube Q1 and the fourth switch tube Q3 use NMOS tubes to realize switching control with the Lightning interface; the first diode D4 and the second diode D5 are respectively connected between the source and drain of the third switch tube Q1 and the fourth switch tube Q3 to provide a unidirectional conduction path to prevent the signal from flowing in reverse, thereby ensuring the stable transmission and switching control of the CC signal.
[0058] In some embodiments, the resistance values of the first resistor R7 and the second resistor R8 are equal, ensuring that the current distribution of the power supply end of the USB-C interface to the base of the first switch tube Q2 and the second switch tube Q4 is balanced, and the resistance values of the third resistor R9 and the fourth resistor R10 are equal, ensuring the consistency of signal transmission from the CC1 and CC2 pins of the USB-C interface to the control circuit.
[0059] Reference Figure 5 An embodiment of the present invention provides another interface conversion circuit. Specifically, the first switch tube Q2 and the second switch tube Q4 are integrated MOS tubes in a two-in-one package form, and the third switch tube Q1 and the fourth switch tube Q3 are integrated triodes in a two-in-one package form.
[0060] Furthermore, the first switch tube Q2 and the second switch tube Q4 use an integrated diode in a two-in-one package, wherein the CC1 pin is connected to the first end of the integrated diode, the CC2 pin is connected to the second end of the integrated diode, and the third end of the integrated diode is connected to the CC pin of the Lightning interface.
[0061] It should be noted that the first end of the integrated diode corresponds to the anode of the first diode in the integrated diode, the second end of the integrated diode corresponds to the anode of the second diode in the integrated diode, and the third end of the seventh switching tube is the common cathode of the two diodes, that is, the common end formed by connecting the cathodes of the two diodes.
[0062] It should also be noted that the first end of the integrated MOS tube and the integrated triode is Q2_E, the second end is Q2_B, the third end is Q1_C, the fourth end is Q1_E, the fifth end is Q1_B, and the sixth end is Q2_C, wherein the first end Q2_E corresponds to the emitter (source) of the second switch tube in the package, the second end Q2_B corresponds to the base (gate) of the second switch tube in the package, the third end Q1_C corresponds to the collector (drain) of the first switch tube in the package, the fourth end Q1_E corresponds to the emitter (source) of the first switch tube in the package, the fifth end Q1_B corresponds to the base (gate) of the first switch tube in the package, and the sixth end Q2_C corresponds to the collector (drain) of the second switch tube in the package.
[0063] Reference Figure 4-6 An embodiment of the invention provides an interface converter, which includes at least a USB-C interface, an interface conversion circuit and a Lighting interface, wherein the USB-C interface is electrically connected to the interface conversion circuit and the Lighting interface respectively, and the interface conversion circuit is electrically connected to the Lighting interface.
[0064] Specifically, the VBUS, DP, DM, and GND networks of the USB-C interface are directly connected to the corresponding pin positions of the Lightning interface through electrical connections. This part does not require any electronic components to participate in the conversion.
[0065] Furthermore, the A6 pin and B6 pin of the USB-C interface are connected to the DP pin of the Lightning interface, ensuring data compatibility between the two interfaces. It not only realizes the data path of the two interfaces, but also ensures the stability and efficiency of high-speed data transmission. The A7 pin and B7 pin of the USB-C interface are connected in parallel to the DM pin of the Lightning interface to ensure the correct transmission of the negative signal during data transmission, further optimizing the bidirectionality of data communication. The A4, B4, A9, and B9 pins of the USB-C interface are connected to the power supply end (VBUS), providing a power output of 5V to 20V, which can meet the different voltage requirements of the connected devices. The A1, A12, B1, B12, G1, G2, G3, and G4 pins of the USB-C interface are connected to the ground end, which can provide a stable reference voltage and good electrical grounding, ensuring that the circuit will not cause signal interference and electrical noise problems due to poor grounding.
[0066] It should be noted that the A6 and B6 pins of the USB-C interface correspond to the attached Figure 6 The DP pin on the USB-C interface corresponds to the A7 pin and the B7 pin. Figure 6 DM pin on the
[0067] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.
Claims
1. An interface conversion circuit, characterized in that: include: A first switch unit (200), a first end of which is connected to the CC1 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC1 pin of the USB-C interface and the CC pin of the Lightning interface; A second switch unit (300), a first end of which is connected to the CC2 pin of the USB-C interface, and a second end of which is connected to the CC pin of the Lightning interface, for realizing signal transmission between the CC2 pin of the USB-C interface and the CC pin of the Lightning interface; A cc switching circuit (100), wherein a first control end thereof is connected to a controlled end of the first switch unit (200), a second control end thereof is connected to a controlled end of the second switch unit (300), and an input end thereof is connected to a CC1 pin and a CC2 pin of a USB-C interface, wherein the cc switching circuit (100) is used to control the transmission of a signal between the first switch unit (200) and a Lightning interface; Alternatively, it is used to control the transmission of signals between the second switch unit (300) and the Lightning interface.
2. An interface conversion circuit as claimed in claim 1, characterized in that: The CC switching circuit (100) comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first switch tube and a second switch tube. The CC1 pin of the USB-C interface is connected to the base of the first switch tube through the first resistor, and is respectively connected to the collector of the second switch tube and the controlled end of the first switch unit (200) through the third resistor. The emitter of the first switch tube is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the first switch tube and the sixth resistor through the second resistor. The CC2 pin of the USB-C interface is connected to the base of the second switch tube through the fourth resistor, and is respectively connected to the collector of the first switch tube and the controlled end of the second switch unit (300) through the sixth resistor. The emitter of the second switch tube is grounded. The power supply end of the USB-C interface is respectively connected to the collector of the second switch tube and the third resistor through the fifth resistor.
3. An interface conversion circuit as claimed in claim 2, characterized in that: The first switch unit (200) comprises a third switch tube, the second switch unit (300) comprises a fourth switch tube, the gate of the third switch tube is connected to the controlled end of the first switch unit (200), the source is connected to the CC1 pin of the USB-C interface, and the drain is connected to the CC pin of the Lighting interface, the gate of the fourth switch tube Q2 is connected to the controlled end of the second switch unit (300), the source is connected to the CC2 pin of the USB-C interface, and the drain is connected to the CC pin of the Lighting interface.
4. An interface conversion circuit as claimed in claim 3, characterized in that: The first switch unit (200) further comprises a first diode, and the second switch unit (300) further comprises a second diode, wherein the anode of the first diode is connected to the source of the third switch tube, and the cathode is connected to the drain of the third switch tube, and the anode of the second diode is connected to the source of the fourth switch tube, and the cathode is connected to the drain of the fourth switch tube.
5. An interface conversion circuit as claimed in claim 4, characterized in that: The first switch tube and the second switch tube are both NPN transistors, and the third switch tube and the fourth switch tube are both NMOS tubes.
6. An interface conversion circuit as claimed in claim 2, characterized in that: The resistance values of the first resistor and the second resistor are equal, and the resistance values of the third resistor and the fourth resistor are equal.
7. An interface conversion circuit as claimed in claim 3, characterized in that: The first switch tube and the second switch tube are integrated MOS tubes in a two-in-one package, and the third switch tube and the fourth switch tube are integrated triodes in a two-in-one package.
8. An interface conversion circuit as claimed in claim 4, characterized in that: The first diode and the second diode are integrated diodes in a two-in-one package.
9. An interface converter, characterized in that: The device at least comprises a USB-C interface, an interface conversion circuit and a Lighting interface, wherein the USB-C interface is electrically connected to the interface conversion circuit and the Lighting interface respectively, and the interface conversion circuit is electrically connected to the Lighting interface, and the interface conversion circuit is the interface conversion circuit as described in any one of claims 1 to 8.
10. An interface converter as claimed in claim 9, characterized in that: The A6 and B6 pins of the USB-C interface are connected to the DP pin of the Lightning interface, and the A7 and B7 pins of the USB-C interface are connected to the DM pin of the Lightning interface. The power supply end of the USB-C interface is respectively connected to the A4 pin, B4 pin, A9 pin, B9 pin of the USB-C interface, and the A1 pin, A12 pin, B1 pin, B12 pin, G1 pin, G2 pin, G3 pin, G4 pin of the USB-C interface and connected to the ground end.