A backflow prevention protection circuit based on a charging chip USB OTG interface

Abstract

The utility model relates to a kind of anti-backfill protection circuit based on charging chip USB OTG interface, the anti-backfill protection circuit includes chip, resistance R1 and resistance R3 are connected with each other in series on the FB pin of the chip, the one end of resistance R3 is connected with resistance R2 and then grounded, the other end of resistance R3 is connected with the pin of USB-IN of the chip and resistance R3 is connected with two series capacitors group after connection, and inductance L1 is connected, inductance L1 is connected with the SW pin of the chip, there is Schottky diode D1 between the two capacitor groups, for hindering current pass, reverse cut-off prevents backfill.The utility model circuit realizes lower cost, without widely changing the structure of circuit, with the previous use does not occur obvious change, development, test, maintenance personnel follow the previous operation specification to carry out process operation, and circuit is simple, and reliability is high.

Description

Technical Field

[0001] This utility model relates to the field of vehicle-mounted equipment, and in particular to a reverse-current protection circuit based on the USB OTG interface of a charging chip. Background Technology

[0002] USB OTG interfaces are widely used in vehicle-mounted head units and vehicle-mounted domain controllers. Typical application scenarios include: peripheral expansion, data sharing, and diagnostics and debugging.

[0003] Peripheral expansion: Connect mobile devices, switch to Host mode via OTG, and read USB flash drives, mobile phones (Android Auto / CarPlay), keyboards / mice, etc.; Firmware upgrade: Update the vehicle system firmware directly via USB flash drive or mobile device; Data sharing: In Peripheral mode, data from the vehicle's infotainment system (such as system logs and multimedia) is exported to an external storage device; Diagnosis and debugging: Connect to a PC via OTG interface to enter ADB debugging mode for software debugging and fault analysis; greatly facilitating the work of developers and improving development efficiency.

[0004] While OTG interfaces have improved efficiency and convenience for developers, testers, and maintenance personnel, when connecting to PCs, have encountered challenges such as equipment burnout and interface damage. This is because PC USB interfaces have a DC 5V (Typ.) output voltage. Different PC brands may have voltages exceeding 5V, reaching 5.1V, 5.2V, 5.3V, etc., creating conditions for reverse voltage flow through the OTG port and jeopardizing normal equipment operation. To avoid economic losses and ensure smooth operation, the circuit design was optimized to completely eliminate the risk of failure at its source.

[0005] like Figure 1 The current path I1 is the normal circuit for the charging chip. When the PC's USB cable is plugged into the vehicle's head unit's USB OTG interface, and the PC's USB VBUS voltage is higher than the USB OTG port voltage, a reverse current path is formed. The current flows back along the I2 path to the charging chip, affecting its normal operation. It can even be transmitted to the BATT+ bus, causing related power chips on the bus to malfunction, ultimately leading to damage to the vehicle's head unit. Utility Model Content

[0006] The purpose of this utility model is to overcome the above-mentioned problems in the existing technology and provide a reverse-current protection circuit based on the USB OTG interface of the charging chip. This protection circuit has the function of preventing reverse current and is used to solve the risks of damage and failure of equipment and vehicle host products during debugging, development, testing and after-sales maintenance.

[0007] To achieve the above-mentioned technical objectives and effects, this utility model is implemented through the following technical solution: A reverse current protection circuit based on the USB OTG interface of a charging chip is disclosed. The reverse current protection circuit includes a chip, and resistors R1 and R3 connected in series are connected to the FB pin of the chip. One end of resistor R3 is connected to resistor R2 and then grounded. The other end of resistor R3 is connected to the USB-IN pin of the chip. Resistor R3 is connected to two capacitor groups connected in series and then to inductor L1. Inductor L1 is connected to the SW pin of the chip. A Schottky diode D1 is connected between the two capacitor groups to impede current flow and prevent reverse current flow.

[0008] In one embodiment of this utility model, the two capacitor groups are a first capacitor group consisting of capacitors C1, C2 and C3 connected in parallel, and a second capacitor group consisting of capacitors C4, C5 and C6 connected in parallel.

[0009] In one embodiment of this utility model, one end of the inductor L1 is further connected in series with a capacitor C15 and a resistor R12', which are connected to the BOOT pin of the chip.

[0010] In one embodiment of this utility model, the anti-backflow protection circuit further includes a USB OTG interface, which is connected to the USB-OUT pin of the chip.

[0011] In one embodiment of this utility model, the Schottky diode D1 is a low VF Schottky diode.

[0012] In one embodiment of this utility model, the anti-backflow protection circuit is also electrically connected to an external circuit.

[0013] In one embodiment of this utility model, the peripheral circuit includes a power control circuit, an A / D / A conversion circuit, a DI input circuit, a DO output circuit, a PWM square wave output circuit, a USB control circuit, and an audio detection circuit. The power control circuit, the A / D / A conversion circuit, the DI input circuit, the DO output circuit, the PWM square wave output circuit, the USB control circuit, and the audio detection circuit are electrically connected to the anti-backflow protection circuit.

[0014] The beneficial effects of this utility model are: 1. By simply adding a Schottky diode D1 in series to the existing circuit design, a reverse current protection circuit can be implemented, resulting in a low circuit implementation cost.

[0015] 2. This utility model does not significantly alter the circuit structure and is not significantly different from previous uses. Development, testing, and maintenance personnel should continue to use the existing operating procedures.

[0016] 3. This utility model has obvious advantages in protection function, completely eliminating the risk of current backflow from the source, and the circuit is simple and highly reliable. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is an existing circuit design diagram without reverse feed protection; Figure 2 This is a circuit design diagram for the present invention with anti-reverse current protection; Figure 3 This is the power control schematic diagram of this utility model; Figure 4 This is a schematic diagram of the A / D and D / A conversion principle of this utility model; Figure 5 This is a schematic diagram of the DI input control principle of this utility model; Figure 6 This is a schematic diagram of the DO output control principle of this utility model; Figure 7 This is a schematic diagram of the PWM square wave output control principle of this utility model; Figure 8 This is a schematic diagram of the USB control principle of this utility model; Figure 9 This is a schematic diagram of the audio detection principle of this utility model. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] This utility model provides a reverse backflow protection circuit based on the USB OTG interface of a charging chip. This protection circuit has reverse backflow protection and is used to solve the risks of damage and failure of equipment and vehicle host products during debugging, development, testing and after-sales maintenance.

[0020] Please see Figure 2This invention provides a reverse current protection circuit based on the USB OTG interface of a charging chip. The reverse current protection circuit includes a chip. Resistors R1 and R3 are connected in series to the FB pin of the chip. One end of resistor R3 is connected to resistor R2 and then grounded. The other end of resistor R3 is connected to the USB-IN pin of the chip. Resistor R3 is also connected to two capacitor groups connected in series and then to inductor L1. The two capacitor groups are a first capacitor group consisting of capacitors C1, C2, and C3 connected in parallel, and a second capacitor group consisting of capacitors C4, C5, and C6 connected in parallel. Inductor L1 is connected to the SW pin of the chip. A Schottky diode D1 is connected between the two capacitor groups, specifically between capacitors C3 and C4, to impede current flow and prevent reverse current flow. One end of inductor L1 is also connected in series with capacitor C15 and resistor R12' and then to the BOOT pin of the chip. The reverse current protection circuit also includes a USB OTG interface, which is connected to the chip's USB-OUT, DP, and DM pins. A capacitor C7 is also connected to the USB-OUT pin and grounded. Schottky diode D1 is a low-VF Schottky diode. The current path I1 is the normal circuit for the charging chip. When the PC's USB cable is plugged into the vehicle's USB OTG interface, and the PC's USB VBUS voltage is higher than the USB OTG port voltage, a reverse current path is formed. The current flows back to the charging chip along path I2. Schottky diode D1 blocks this current flow, effectively cutting off the circuit and protecting the charging chip from damage. Due to the characteristics of Schottky diode D1, the voltage drop generated by the forward conduction voltage (VF) is dynamically compensated by resistors R1, R2, and R3 connected to the charging chip's FB pin, ensuring that the USB OTG port VBUS voltage meets requirements.

[0021] Please see Figure 2 In one embodiment of this utility model, the chip further includes a CC1 pin, a CC2 pin, a VCC pin, and a GND pin. The CC1 pin is connected to ground via a resistor R4. One end of the CC2 pin is connected to the positive terminal VCC of the power supply via a resistor R5. The other end of the CC2 pin is connected to a resistor R6 connected in series with a transistor Q1. One pin of the transistor is connected to a resistor R7 and a capacitor C9 connected in parallel, then connected in series with a resistor R8 and finally connected to the SOC. The other pin of the transistor is grounded. One end of the VCC pin is connected to a capacitor C8 and then grounded. The other end of the VCC pin is connected to the positive terminal VCC of the power supply. The GND pin is grounded.

[0022] Please see Figure 2In one embodiment of this invention, the chip further includes a VIN pin, an EN / SYNC pin, an FLT pin, a DM-OUT pin, a DP-OUT pin, an RT pin, and a BIAS pin. The VIN and EN / SYNC pins are connected to resistor R11 and then to a third capacitor bank consisting of capacitors C11, C12, C13, and C14 connected in parallel. One end of the third capacitor bank is grounded, and the other end is connected to the BATT+ bus. The FLT pin is connected to resistor R10 and then to the positive terminal VCC of the power supply. The DM-OUT and DP-OUT pins are connected to the SOC. The RT pin is connected to resistor R9 and then grounded. The BIAS pin is connected to capacitor C10 and then grounded.

[0023] Please participate Figures 2 to 9 In another embodiment of this utility model, the anti-backflow protection circuit is also electrically connected to an external circuit. The external circuit includes a power control circuit, an A / D / A conversion circuit, a DI input circuit, a DO output circuit, a PWM square wave output circuit, a USB control circuit, and an audio detection circuit. The power control circuit, A / D / A conversion circuit, DI input circuit, DO output circuit, PWM square wave output circuit, USB control circuit, and the audio detection circuit are electrically connected to the anti-backflow protection circuit. Specifically, the BATT pin of the power control circuit is connected to the anti-backflow protection circuit, the +3.3V pin of the A / D / A conversion circuit is connected to the anti-backflow protection circuit, the DI input circuit is connected to the A / D / A conversion circuit, the DO output circuit is connected to the A / D / A conversion circuit, and the USB control circuit is connected to the USBOTG pin of the anti-backflow protection circuit via the USB +5V pin. The audio detection circuit is connected to the DI input circuit, and the OUT1 pin of the audio detection circuit chip BA10393F is connected to the B pin of the transistor Q25 of the PWM square wave output circuit.

[0024] In summary, this utility model provides a reverse current protection circuit based on the USB OTG interface of a charging chip. When a PC's USB cable is plugged into the USB OTG interface of a vehicle's head unit, if reverse current occurs, the Schottky diode D1 blocks the current flow, effectively cutting off the circuit in reverse. This protects the normal operation of the charging chip. Due to the characteristics of the Schottky diode D1, the voltage drop generated by the forward conduction voltage (VF) is dynamically compensated by resistors R1, R2, and R3 connected to the FB pin of the charging chip, thereby ensuring that the VBUS (voltage bus in the USB interface) voltage of the USB OTG port meets the requirements.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A reverse-current protection circuit based on a charging chip's USB OTG interface, characterized in that, The anti-reverse current protection circuit includes a chip. A series resistor R1 and a resistor R3 are connected to the FB pin of the chip. One end of the resistor R3 is connected to the ground via a resistor R2. The other end of the resistor R3 is connected to the USB-IN pin of the chip. The resistor R3 is connected to two series capacitor banks and then to an inductor L1. The inductor L1 is connected to the SW pin of the chip. A Schottky diode D1 is connected between the two capacitor banks to impede current flow and prevent reverse current flow.

2. The anti-reverse current protection circuit according to claim 1, characterized in that, The two capacitor groups are a first capacitor group consisting of capacitors C1, C2 and C3 connected in parallel, and a second capacitor group consisting of capacitors C4, C5 and C6 connected in parallel.

3. The anti-reverse current protection circuit according to claim 1, characterized in that, One end of the inductor L1 is connected in series with a capacitor C15 and a resistor R12', which are then connected to the BOOT pin of the chip.

4. The anti-reverse current protection circuit according to claim 1, characterized in that, The anti-backflow protection circuit also includes a USB OTG interface, which is connected to the USB-OUT pin of the chip.

5. The anti-reverse current protection circuit according to claim 1, characterized in that, The Schottky diode D1 is a low VF Schottky diode.

6. The anti-reverse current protection circuit according to claim 1, characterized in that, The anti-backflow protection circuit is also electrically connected to an external circuit.

7. The anti-reverse current protection circuit according to claim 6, characterized in that, The peripheral circuit includes a power control circuit, an A / D / A conversion circuit, a DI input circuit, a DO output circuit, a PWM square wave output circuit, a USB control circuit, and an audio detection circuit. The power control circuit, the A / D / A conversion circuit, the DI input circuit, the DO output circuit, the PWM square wave output circuit, the USB control circuit, and the audio detection circuit are electrically connected to the anti-backflow protection circuit.

Images