Automotive USB interface protection circuit, USB interface module and automobile

Abstract

The utility model discloses an automotive USB interface protection circuit, a USB interface module and an automobile. The protection circuit comprises MOSFET tubes M1 and M2 and resistors R1 and R2, the grid electrode of the MOSFET tube M1 is connected with the grid electrode of the MOSFET tube M2; the power supply VCC is grounded after passing through the resistor R1 and the resistor R2 which are sequentially connected in series; a terminal is led out between the resistor R1 and the resistor R2 and is connected to the grid electrode of the MOSFET tube M1; an SOCD + terminal is led out of the source electrode of the MOSFET M1, an SOCD-terminal is led out of the source electrode of the MOSFET M2, and the SOCD + terminal and the SOCD-terminal are used for being connected to a USB controller chip; a COND + terminal is led out from the drain electrode of the MOSFET M1, a COND-terminal is led out from the drain electrode of the MOSFET M2, and the COND + terminal and the COND-terminal are used for being connected with inserted external USB equipment. The USB interface protection circuit has the advantages that overvoltage at the USB interface can be effectively protected, damage of overvoltage to a USB interface chip is avoided, and the electrical safety of the USB interface is improved.

Description

Technical Field

[0001] The utility model relates to the field of automobile electrical safety, in particular to a vehicle USB interface protection circuit and a USB interface module, and a vehicle. Background Art

[0002] With the popularization of vehicles and the development of mobile Internet technology, users have more and more demands for USB access to vehicles for charging and vehicle-computer interaction during the use of vehicles. Therefore, vehicle-mounted USB interfaces are increasingly used in vehicles, such as a vehicle-mounted USB power interface device, a USB socket device and a USB plug device with patent application number 201220099028.1, wherein the vehicle-mounted USB power interface device includes a USB socket device and a USB plug device, the USB socket device includes: a shell, a power adapter is arranged in the shell, the power adapter is respectively connected to a plurality of USB interfaces, a plurality of bayonet ports are also arranged in the shell, and openings corresponding to the USB interfaces and the bayonet ports are respectively arranged on the shell, and the USB plug device includes: a USB plug, the end of the USB plug is a plug piece, a bayonet body is arranged on the USB plug, a bayonet body front end is provided with a hook, and an unlocking handle is arranged on the bayonet body. The vehicle-mounted USB power interface device of the utility model is adopted, in conjunction with the USB socket device and the USB plug device, and the vehicle-mounted power supply is used to charge or provide power for digital devices, which can prevent the USB plug from loosening and falling off, and is convenient for use when traveling by car.

[0003] This traditional vehicle-mounted USB interface generally does not have the overvoltage protection function of the USB chip. When the voltage exceeds the safety threshold, the USB control chip inside the USB interface will be damaged, making the USB interface ineffective and unable to charge or interact normally. It may even cause an electrical safety accident in the vehicle. Therefore, the overvoltage protection of the USB interface is very important. The prior art generally has a built-in USB overvoltage protection chip in the USB to protect the voltage at the USB interface. However, the dedicated overvoltage chip has the defect of high cost. For the large number of USB interfaces in the vehicle in the prior art, the cost of the USB interface in the vehicle is increased. Therefore, the solution of using a dedicated chip for protection cannot meet the dual requirements of cost and reliability. Utility Model Content

[0004] The utility model aims to overcome the deficiencies of the prior art and provide a vehicle USB interface protection circuit, a USB interface module, and a vehicle, which adopt MOSFET tubes to realize overvoltage protection of the USB interface and realize low-cost USB interface overvoltage protection.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a car USB interface protection circuit, comprising: MOSFET tubes M1, M2 and resistors R1, R2; the gate of the MOSFET tube M1 is connected to the gate of the MOSFET tube M2; the power supply VCC is grounded after being connected in series with the resistors R1 and R2; a terminal is connected to the gate of the MOSFET tube M1 between the resistors R1 and R2; the source of the MOSFET tube M1 leads to the SOC_D+ terminal, the source of the MOSFET tube M2 leads to the SOC_D- terminal, and the SOC_D+ terminal and the SOC_D- terminal are used to be connected to the USB controller chip respectively; the drain of the MOSFET tube M1 leads to the CON_D+ terminal, and the drain of the MOSFET tube M2 leads to the CON_D- terminal, and the CON_D+ terminal and the CON_D- terminal are used to connect to the inserted external USB device.

[0006] The MOSFET tube M1 is an N-MOSFET tube.

[0007] The MOSFET tube M2 is an N-MOSFET tube.

[0008] The power supply VCC is a 5V power supply.

[0009] The resistance value of the resistor R2 is greater than the resistance value of the resistor R1.

[0010] The working principle of the overvoltage protection circuit includes:

[0011] The circuit overvoltage protection principle is as follows:

[0012] 1. The left side of the N-MOSFET, such as the No. 2 (source) pin of M1 & M2 in the figure, is connected to the USB interface of the controller chip.

[0013] 2. The right side of the N-MOSFET, such as the No. 3 (drain) pin of M1 & M2 in the figure, is connected to the external USB connector.

[0014] 3. Pin 1 (gate) of the N-MOSFET is connected together and connected between resistors R1 and R2.

[0015] 4. One end of the resistor R1 (240 ohms) is connected to the 5V power supply and the other end is connected to the No. 1 (gate) pin of the N-MOSFET.

[0016] 5. Connect one end of the resistor R2 (2k ohm) to the GND ground wire and the other end to the No. 1 (gate) pin of the N-MOSFET.

[0017] 6. During normal communication, the voltage of pin 1 (gate) of N-MOSFET is higher than the USB signal lines D+ & D-, the MOSFET is turned on normally, and the data signal can be directly transmitted in both directions.

[0018] 7. When CON_D+ / D- is over-voltage, the SOC_D+ / D- voltage will also increase. When it rises to about 5V, MOSFETM1 / M2 will be turned off. The CON_D+ / D- voltage continues to rise, and the SOC_D+ / D- voltage will be clamped at about 5V, thereby protecting the chip end.

[0019] A vehicle USB interface module is characterized in that the vehicle USB interface protection circuit is integrated into the vehicle USB interface module.

[0020] A car comprises the vehicle USB interface protection circuit or the vehicle USB interface module.

[0021] The advantages of the utility model are: it can effectively protect the USB interface from overvoltage, avoid damage to the USB interface chip caused by overvoltage, and improve the electrical safety of the USB interface; compared with the traditional vehicle USB overvoltage protection chip, the circuit principle is simple, and the use of general N-MOSFET tubes can achieve lower costs. The requirements for N-MOSFET tubes are also reduced, and it is highly substitutable, and can also be replaced by domestic semiconductor companies. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following is a brief description of the contents expressed in the drawings of the present invention and the symbols in the drawings:

[0023] Figure 1 This is a schematic diagram of the USB interface protection circuit of the utility model. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0025] With the development of intelligent electrification of vehicles, the number of USB devices installed in vehicles is also increasing. If traditional dedicated chips are integrated into the USB interface circuit, the cost of the vehicle on the USB interface module will increase. Therefore, it is necessary to provide a simple, low-cost, stable and reliable USB interface protection circuit to avoid the failure of the USB interface chip caused by overvoltage of the USB interface. The specific solution is as follows:

[0026] like Figure 1As shown, this embodiment involves a USB interface protection circuit for automobiles, which utilizes the basic characteristics of N-MOSFET tubes to protect the USB port of the control chip and realize the function of overvoltage protection. Compared with the traditional vehicle USB overvoltage protection chip, the circuit principle is simple, and the use of general N-MOSFET tubes can achieve lower costs. The requirements for N-MOSFET tubes are also reduced, and they are highly substitutable, and can also be replaced by domestic semiconductor companies.

[0027] like Figure 1 As shown, the circuit structure of the vehicle USB interface protection circuit includes: MOSFET tubes M1, M2 and resistors R1, R2; wherein:

[0028] Among them, MOSFET tube M1 and MOSFET tube M2 are both N-MOSFET tubes, and N-channel MOSFET has an N-channel region located between the source and drain terminals. It is a four-terminal device, and its terminals are gate, drain, source, and body. In this field effect transistor, the drain and source are heavily doped n+ regions, and the substrate or body is P-type. Current flow occurs in this type of MOSFET due to negatively charged electrons. When we apply a positive voltage with repulsive force on the gate terminal, the holes present under the oxide layer will be pushed down into the substrate. The depletion region is composed of bound negative charges associated with acceptor atoms. When the electrons arrive, a channel is formed. The positive voltage also attracts electrons from the n+ source and drain regions into the channel. Now, if a voltage is applied between the drain and source, the current will flow freely between the source and drain, and the gate voltage will control the electrons in the channel. If we apply a negative voltage, a hole channel will be formed under the oxide layer instead of a positive voltage.

[0029] Based on the above characteristics of N-MOSFET tube, the purpose of overvoltage protection can be achieved by controlling the gate voltage. Figure 1 As shown, the gate of the MOSFET tube M1 and the gate of the MOSFET tube M2 are connected together; then the power supply VCC is connected to the ground after being connected in series with the resistors R1 and R2; a terminal is connected between the resistors R1 and R2 to the gate of the MOSFET tube M1; in this way, the gate voltages of the MOSFET tubes M1 and M2 can be controlled based on the voltage obtained by the resistor voltage division of R1 and R2, thereby controlling the off state of the MOSFET tubes M1 and M2.

[0030] Then the circuit needs to be connected to the USB interface module, where the source and drain of MOSFET tube M1 and MOSFET tube M2 are extracted respectively. Figure 1As shown, the source of MOSFET tube M1 leads to SOC_D+ terminal, the source of MOSFET tube M2 leads to SOC_D- terminal, SOC_D+ terminal and SOC_D- terminal are used to connect to USB controller chip respectively; the drain of MOSFET tube M1 leads to CON_D+ terminal, the drain of MOSFET tube M2 leads to CON_D- terminal, the CON_D+ terminal and CON_D- terminal are used to connect to the inserted external USB device. The USB interface protection circuit of the present application is integrated into the USB interface module, wherein the SOC_D+ terminal and SOC_D- terminal of the circuit are respectively connected to the USB interface control chip, the CON_D+ terminal and CON_D- terminal are used to establish connection with the external device after the external device is inserted into the USB interface, thereby achieving the purpose of connecting MOSFET tube M1 and MOSFET tube M2 to the USB interface control chip and the external device, thereby avoiding overvoltage damage between the external device and the USB interface control chip.

[0031] Generally, the voltage of the interface management control chip in the USB interface circuit is below 5V, so the voltage of the VCC power supply divided by R1 and R2 is 5V, that is, the power supply VCC is a 5V power supply. And the resistance of resistor R1 and R2 is required to be greater than the resistance of resistor R1 when dividing the voltage. In this application, the resistance of resistor R1 is 240Ω, and the resistance of resistor R2 is 2K ohms, so that the voltage obtained by the voltage division of resistors R1 and R2 is sent to the gate of MOSFET tubes M1 and M2. Resistors R1 and R2 are realized by 0402 chip resistors, which have the advantage of high precision.

[0032] Based on the above circuit, the overvoltage protection principle of the circuit in this embodiment is as follows:

[0033] 1. The left side of the N-MOSFET, such as the No. 2 (source) pin of M1 & M2 in the figure, is connected to the USB interface of the controller chip.

[0034] 2. The right side of the N-MOSFET, such as the No. 3 (drain) pin of M1 & M2 in the figure, is connected to the external USB connector.

[0035] 3. Pin 1 (gate) of the N-MOSFET is connected together and connected between resistors R1 and R2.

[0036] 4. One end of the resistor R1 (240 ohms) is connected to the 5V power supply and the other end is connected to the No. 1 (gate) pin of the N-MOSFET.

[0037] 5. Connect one end of the resistor R2 (2k ohm) to the GND ground wire and the other end to the No. 1 (gate) pin of the N-MOSFET.

[0038] 6. During normal communication, the voltage of pin 1 (gate) of N-MOSFET is higher than the USB signal lines D+ & D-, the MOSFET is turned on normally, and the data signal can be directly transmitted in both directions.

[0039] 7. When CON_D+ / D- is over-voltage, the SOC_D+ / D- voltage will also increase. When it rises to about 5V, MOSFETM1 / M2 will be turned off. The CON_D+ / D- voltage continues to rise, and the SOC_D+ / D- voltage will be clamped at about 5V, thereby protecting the chip end.

[0040] This embodiment also provides a vehicle USB interface module, which is integrated with a USB interface control chip in an integrated manner, and the vehicle USB interface protection circuit in the above embodiment is integrated in the vehicle USB interface module. Based on the integrated vehicle USB interface protection circuit, the purpose of USB overvoltage protection of the vehicle can be achieved.

[0041] This embodiment also provides a car, in which a USB module is integrated with the car USB interface protection circuit in the above embodiment or the car adopts the car USB interface module in the above embodiment.

[0042] In the above embodiment, due to the overvoltage protection circuit composed of MOSFET M1 and M2, the overvoltage at the USB interface can be effectively protected, the damage to the USB interface chip caused by overvoltage is avoided, and the electrical safety of the USB interface is improved; compared with the traditional vehicle USB overvoltage protection chip, the circuit principle is simple, and the use of general N-MOSFET tubes can achieve lower costs. The requirements for N-MOSFET tubes are also reduced, and they are highly substitutable, and can also be replaced by domestic semiconductor companies.

[0043] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A vehicle USB interface protection circuit, characterized in that: include: MOSFET tubes M1, M2 and resistors R1, R2; the gate of MOSFET tube M1 is connected with the gate of MOSFET tube M2; the power supply VCC is connected to ground after being connected in series with resistors R1 and R2; a terminal is connected to the gate of MOSFET tube M1 between resistors R1 and R2; the source of MOSFET tube M1 is connected to SOC_D+ terminal, the source of MOSFET tube M2 is connected to SOC_D- terminal, and SOC_D+ terminal and SOC_D- terminal are used to be connected to USB controller chip respectively; the drain of MOSFET tube M1 is connected to CON_D+ terminal, the drain of MOSFET tube M2 is connected to CON_D- terminal, and the CON_D+ terminal and CON_D- terminal are used to connect to the inserted external USB device.

2. A vehicle USB interface protection circuit as claimed in claim 1, characterized in that: The MOSFET tube M1 is an N-MOSFET tube.

3. A vehicle USB interface protection circuit as claimed in claim 1, characterized in that: The MOSFET tube M2 is an N-MOSFET tube.

4. A vehicle USB interface protection circuit as described in any one of claims 1 to 3, characterized in that: The power supply VCC is a 5V power supply.

5. A vehicle USB interface protection circuit as claimed in claim 4, characterized in that: The resistance value of the resistor R2 is greater than the resistance value of the resistor R1.

6. A vehicle USB interface module, characterized in that: The vehicle USB interface module is integrated with a vehicle USB interface protection circuit as described in any one of claims 1-5.

7. A car, characterized in that: The automobile comprises a vehicle USB interface protection circuit as described in any one of claims 1 to 5 or comprises a vehicle USB interface module as described in claim 6.

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