USB signal overvoltage protection circuit

Abstract

The utility model provides a USB signal overvoltage protection circuit. The USB signal overvoltage protection circuit can prevent a USB controller from being damaged by high voltage input by external equipment through a USB2DN or USB2DP signal line. Comprising a voltage control module which is connected with the USB controller and the USB2.0 connector and is used for cutting off power supply to the USB2.0 connector when an overvoltage condition occurs; the logic driving module is connected with the USB controller and the USB2.0 connector, and is used for clamping the signal voltage of a signal end USB2DN or a signal end USB2DP when an overvoltage condition occurs, so as to protect the USB controller; and the protection control module is connected with the USB controller, the USB2.0 connector, the voltage control module and the logic driving module, and is used for detecting the voltage of the signal end USB2DN or the signal end USB2DP, and outputting a corresponding signal to the voltage control module and the logic driving module to perform a protection action when the signal voltage exceeds a set value.

Description

Technical Field

[0001] This utility model relates to the field of USB overvoltage protection technology, specifically a USB signal overvoltage protection circuit. Background Technology

[0002] The USB2_DN and USB2_DP signal terminals of the USB controller are directly connected to external USB peripherals. However, for some non-compliant USB peripherals and some aging USB peripherals, the 5V voltage and the USB2_DN or USB2_DP signal are often short-circuited together. In this case, the USB2_DN or USB2_DP signal line will backflow the 5V voltage into the USB controller. If protection is not carried out in time, it will cause damage to the USB controller. Utility Model Content

[0003] To address the aforementioned issues, this invention provides a USB signal overvoltage protection circuit, which can prevent the USB controller from being damaged by high voltage input from external devices via the USB2_DN or USB2_DP signal lines.

[0004] This utility model adopts the following technical solution: a USB signal overvoltage protection circuit, connected to a USB controller, wherein the signal terminals USB2_DN and USB2_DP of the USB controller are respectively connected to pins 2 and 3 of a USB 2.0 connector, the USB 2.0 connector is connected to a peripheral device, and the USB signal overvoltage protection circuit includes:

[0005] The voltage control module is connected to both the USB controller and the USB 2.0 connector, and is used to cut off the power supply to the USB 2.0 connector in the event of an overvoltage condition.

[0006] The logic drive module is connected to both the USB controller and the USB 2.0 connector. It is used to clamp the signal voltage of the signal terminal USB2_DN or the signal terminal USB2_DP in the event of an overvoltage, so as to protect the USB controller.

[0007] The protection control module is connected to the USB controller, USB2.0 connector, voltage control module, and logic drive module. It is used to detect the voltage of the signal terminal USB2_DN or the signal terminal USB2_DP, and output a corresponding signal to the voltage control module and logic drive module to perform protection action when the signal voltage exceeds the set value.

[0008] Furthermore, the protection control module includes an MCU microcontroller, resistors R1 to R3, and an LED D1. One end of resistor R1 is connected to the ADC1 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the signal terminal USB2_DN of the USB controller and pin 2 of the USB 2.0 connector. One end of resistor R2 is connected to the ADC2 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the signal terminal USB2_DP of the USB controller and pin 3 of the USB 2.0 connector. Pin 4 of the USB 2.0 connector is grounded. One end of resistor R3 is connected to the I / O1 pin of the MCU microcontroller, and the other end of resistor R3 is connected to the positive terminal of LED D1. The negative terminal of LED D1 is grounded.

[0009] Furthermore, the voltage control module includes a power manager U1, a resistor R4, and capacitors C1 to C4. The power manager U1 uses an ET20164 chip. Pin 4 of the power manager U1 is connected to one end of the resistor R4 and the I / O3 pin of the MCU microcontroller. The other end of the resistor R4 is grounded. Pin 5 of the power manager U1 is connected to one end of capacitors C1 and C2 and then connected to a 5V power supply voltage. The other ends of capacitors C1 and C2 are connected to ground. Pin 2 of the power manager U1 is grounded. Pin 1 of the power manager U1 is connected to one end of capacitors C3 and C4 and pin 1 of the USB 2.0 connector. The other ends of capacitors C3 and C4 are grounded.

[0010] Furthermore, the logic driving module includes resistors R5 and R6, MOSFETs Q1 and Q2, and a transient voltage suppressor D2. The transient voltage suppressor D2 uses a BV-SRV05-4A_C-1 chip. Pins 1 and 6 of the transient voltage suppressor D2 are connected to signal terminals USB2_DN and USB2_DP, respectively. Pin 2 of the transient voltage suppressor D2 is grounded. The I / O2 pin of the MCU microcontroller is connected to one end of resistor R6 and the gate of MOSFET Q2. The other end of resistor R6 is grounded. The drain of MOSFET Q2 is connected to one end of resistor R5 and the gate of MOSFET Q1. The sources of MOSFETs Q1 and Q2 are both grounded. The other end of resistor R5 is connected to a 5V power supply. The drain of MOSFET Q1 is connected to pin 5 of the transient voltage suppressor D2.

[0011] Furthermore, the signal voltages of the signal terminals USB2_DN and USB2_DP are 0 to 3.3V. When the protection control module detects that the signal voltage exceeds 3.3V, it outputs a corresponding signal to the voltage control module and the logic drive module to perform protection actions.

[0012] Furthermore, in the event of an overvoltage condition, the signal voltage of the signal terminal USB2_DN or the signal terminal USB2_DP is clamped to 0.7V.

[0013] The beneficial effects of this utility model are that, through the voltage control module, logic drive module, and protection control module, when a 5V voltage and a short circuit of the USB2_DN or USB2_DP signal occur together in a peripheral connected to the USB2.0 connector, the protection control module can quickly detect the overvoltage situation and perform timely protection processing. The protection of the USB controller is achieved through the action of the logic drive module and the protection control module, thereby preventing the USB controller from being damaged by high voltage input from external devices through the USB2_DN or USB2_DP signal lines, which has good practical value. Attached Figure Description

[0014] Figure 1 This is a structural block diagram of the present invention;

[0015] Figure 2 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0016] like Figure 1 , Figure 2 As shown, this utility model discloses a USB signal overvoltage protection circuit, which is connected to a USB controller. The signal terminals USB2_DN and USB2_DP of the USB controller are respectively connected to pins 2 and 3 of the USB 2.0 connector. The USB 2.0 connector is connected to a peripheral device. Commonly used USB controller models include Loongson 7A1000 and Phytium X100 chips. The USB signal overvoltage protection circuit includes:

[0017] The voltage control module, connected to both the USB controller and the USB 2.0 connector, is used to cut off the power supply to the USB 2.0 connector in the event of an overvoltage condition.

[0018] The logic drive module is connected to both the USB controller and the USB 2.0 connector. It is used to clamp the signal voltage of the USB2_DN or USB2_DP signal terminals in the event of an overvoltage condition to protect the USB controller.

[0019] The protection control module is connected to the USB controller, USB2.0 connector, voltage control module, and logic drive module. It is used to detect the voltage of the signal terminal USB2_DN or the signal terminal USB2_DP, and output the corresponding signal to the voltage control module and logic drive module to perform protection action when the signal voltage exceeds the set value.

[0020] The protection control module includes an MCU microcontroller, resistors R1-R3, and an LED D1. The MCU microcontroller uses an existing MCU chip. One end of resistor R1 is connected to the ADC1 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the USB2_DN signal terminal of the USB controller and pin 2 of the USB 2.0 connector. One end of resistor R2 is connected to the ADC2 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the USB2_DP signal terminal of the USB controller and pin 3 of the USB 2.0 connector. Pin 4 of the USB 2.0 connector is grounded. One end of resistor R3 is connected to the I / O1 pin of the MCU microcontroller, and the other end of resistor R3 is connected to the positive terminal of LED D1. The negative terminal of LED D1 is grounded. The I / O4 pin of the MCU microcontroller is connected to the USB controller and can be used for related operations of the USB controller.

[0021] The USB2_DN and USB2_DP signals are connected to the ADC and ADC2 pins of the MCU microcontroller via resistors R1 and R2, respectively. This allows for precise detection of the voltage values ​​at the USB2_DN and USB2_DP signal terminals of the USB controller. The normal voltage range is between 0 and 3.3V. Once a voltage greater than 3.3V is detected, a protection operation can be initiated to cut off the power supply voltage P5V_USB of the USB2.0 connector.

[0022] Resistors R1 and R2 are 1M ohms resistors, the purpose of which is to better isolate the influence of the MCU microcontroller on normal USB signal transmission, so that abnormal situations will not occur during normal USB signal transmission due to this detection function.

[0023] When the MCU microcontroller provides a high level to the gate of MOSFET Q2, MOSFET Q2 is turned on, and MOSFET Q1 will be turned off. Pin 5 of the transient voltage suppressor D2 connected to Q1 will be in a floating state, so as not to affect the normal signal transmission of USB2_DN and USB2_DP.

[0024] Resistor R3 and LED D1 are LED indicator signals controlled by the MCU microcontroller. They are normally off. When a high voltage is detected on the USB2_DN or USB2_DP signal and the circuit is in protection mode, the MCU microcontroller sends a high-level signal to light up LED D1, so that the user knows that the USB peripheral is faulty and the circuit is in protection mode, and the USB peripheral must be replaced.

[0025] The voltage control module includes a power manager U1, resistor R4, and capacitors C1 to C4. The power manager U1 uses an ET20164 chip. Pin 4 of the power manager U1 is connected to one end of resistor R4 and the I / O3 pin of the MCU microcontroller. The other end of resistor R4 is grounded. Pin 5 of the power manager U1 is connected to one end of capacitors C1 and C2 and then connected to a 5V power supply voltage. The other ends of capacitors C1 and C2 are connected and then grounded. Pin 2 of the power manager U1 is grounded. Pin 1 of the power manager U1 is connected to one end of capacitors C3 and C4 and pin 1 of the USB 2.0 connector. The other ends of capacitors C3 and C4 are grounded.

[0026] In addition, capacitors C1 and C2 are filter capacitors for the system power supply voltage terminal P5V_VCC; capacitors C3 and C4 are filter capacitors for the power supply voltage terminal P5V_USB.

[0027] Pin 3 of the power manager U1 is FLT#, which outputs a low level to the USB controller in case of overvoltage, to indicate that an abnormality exists to the USB controller.

[0028] Pin 4 of the power manager U1 is the EN enable signal terminal. When the MCU microcontroller outputs a high level, the power manager U1 is turned on. Pin 1 of the power manager U1 outputs P5V_USB voltage to provide 5V voltage to the USB 2.0 connector.

[0029] The logic driver module includes resistors R5 and R6, MOSFETs Q1 and Q2, and transient voltage suppressor D2. Transient voltage suppressor D2 uses a BV-SRV05-4A_C-1 chip. Pins 1 and 6 of transient voltage suppressor D2 are connected to signal terminals USB2_DN and USB2_DP, respectively. Pin 2 of transient voltage suppressor D2 is grounded. The I / O2 pin of the MCU microcontroller is connected to one end of resistor R6 and the gate of MOSFET Q2. The other end of resistor R6 is grounded. The drain of MOSFET Q2 is connected to one end of resistor R5 and the gate of MOSFET Q1. The sources of MOSFETs Q1 and Q2 are grounded. The other end of resistor R5 is connected to a 5V power supply. The drain of MOSFET Q1 is connected to pin 5 of transient voltage suppressor D2.

[0030] Transient voltage suppressor D2 serves two main purposes. First, it acts as a TVS (Transient Voltage Suppressor) protector for USB signals (i.e., USB2_DN and USB2_DP signals). When external electrostatic discharge (ESD) is introduced into the USB2_DN and USB2_DP signals, the transient voltage suppressor D2 can momentarily conduct, clamping the high pulse voltage value of the ESD and protecting the USB controller. Second, the two internal diodes near pin 6 of the transient voltage suppressor D2 work in conjunction with the MOSFET Q1. When the MOSFET Q1 is turned on, the forward voltage drop of these two internal diodes, approximately 0.7V, can clamp the USB2_DN and USB2_DP signals.

[0031] The function of resistor R6 is to provide a steady low level pull-down to MOSFET Q2. Before the MCU microcontroller starts up, MOSFET Q2 is in the off state. Resistor R5 will apply the voltage P5V_VCC to the gate of MOSFET Q1, making MOSFET Q1 conduct. The drain of MOSFET Q1 and pin 5 of the transient voltage suppressor are both grounded, thereby clamping the signal voltages of USB2_DN and USB2_DP.

[0032] The signal voltage of the USB2_DN and USB2_DP terminals is 0 to 3.3V. When the protection control module detects that the signal voltage exceeds 3.3V, it outputs a corresponding signal to the voltage control module and logic drive module to perform protection action. In the event of overvoltage, the signal voltage of the USB2_DN or USB2_DP terminal is clamped to 0.7V.

[0033] Figure 2 In this context, P5V_VCC represents the 5V system power supply voltage; P5V_USB represents the 5V voltage supplied to the USB 2.0 connector.

[0034] The working process of this utility model is as follows:

[0035] During normal use, the MCU microcontroller outputs a high-level signal to pin 4 of the power manager U1 via the I / O3 pin as a turn-on signal to turn on the P5V_USB voltage; at the same time, it outputs a high-level signal to the gate of the MOSFET Q2 via the I / O2 pin, causing pin 5 of the transient voltage suppressor D2 to float and be in a state of electrostatic discharge (ESD) protection.

[0036] When an abnormal USB peripheral is plugged into the USB 2.0 connector, such as when the signal terminal USB2_DN and VCC 5V are shorted together, a 5V voltage will be present on the signal terminal USB2_DN. This voltage is sent to the ADC1 pin of the MCU microcontroller through resistor R1, which immediately triggers the protection mechanism of the existing programming settings in the MCU microcontroller. Subsequently, a low level is output to pin 4 of the power manager U1 to turn off the output voltage of P5V_USB. At the same time, a low level is output to the gate of MOSFET Q2, which in turn turns on MOSFET Q1. Using the diode inside the transient voltage suppressor D2, the USB_DN signal is immediately clamped from 5V to about 0.7V to protect the USB controller. At the same time, a high level signal is output to light up the LED D1, so that the user knows that the USB protection circuit has entered the protection state and that the USB peripheral is in an abnormal condition and must be replaced.

[0037] When the USB peripheral is removed, the MCU microcontroller polls and detects that the voltage of the signal terminal USB2_DN or the signal terminal USB2_DP is no longer greater than the normal 3.3V. Then, it outputs a high level to pin 4 of the power manager U1 and the gate of the MOSFET Q2 so that the user can perform normal USB operation.

[0038] In summary, the protection control module can accurately detect the voltage of the USB2_DN or USB2_DP signal terminals and quickly initiate protection actions. The logic drive module can quickly discharge excessive voltage on the USB2_DN or USB2_DP signal terminals when the protection action is initiated, while under normal circumstances, it will not affect the USB signal transmission, thus effectively preventing the USB controller from being damaged by high voltage input from external devices through the USB2_DN or USB2_DP signal lines.

[0039] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A USB signal overvoltage protection circuit, connected with a USB controller, signal terminal USB2_DN and signal terminal USB2_DP of the USB controller are connected with 2 and 3 pins of a USB2.0 connector respectively, the USB2.0 connector is connected with an external device, characterized in that: The USB signal overvoltage protection circuit includes: ​ The voltage control module is connected to both the USB controller and the USB 2.0 connector, and is used to cut off the power supply to the USB 2.0 connector in the event of an overvoltage condition. The logic drive module is connected to both the USB controller and the USB 2.0 connector. It is used to clamp the signal voltage of the signal terminal USB2_DN or the signal terminal USB2_DP in the event of an overvoltage, so as to protect the USB controller. The protection control module is connected to the USB controller, USB2.0 connector, voltage control module, and logic drive module. It is used to detect the voltage of the signal terminal USB2_DN or the signal terminal USB2_DP, and output a corresponding signal to the voltage control module and logic drive module to perform protection action when the signal voltage exceeds the set value.

2. The USB signal overvoltage protection circuit of claim 1, wherein: The protection control module includes an MCU microcontroller, resistors R1 to R3, and an LED D1. One end of resistor R1 is connected to the ADC1 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the signal terminal USB2_DN of the USB controller and pin 2 of the USB 2.0 connector. One end of resistor R2 is connected to the ADC2 pin of the MCU microcontroller, and the other end of resistor R1 is connected to the signal terminal USB2_DP of the USB controller and pin 3 of the USB 2.0 connector. Pin 4 of the USB 2.0 connector is grounded. One end of resistor R3 is connected to the I / O1 pin of the MCU microcontroller, and the other end of resistor R3 is connected to the positive terminal of LED D1. The negative terminal of LED D1 is grounded.

3. The USB signal overvoltage protection circuit of claim 2, wherein: The voltage control module includes a power manager U1, a resistor R4, and capacitors C1 to C4. The power manager U1 uses an ET20164 chip. Pin 4 of the power manager U1 is connected to one end of the resistor R4 and the I / O3 pin of the MCU microcontroller. The other end of the resistor R4 is grounded. Pin 5 of the power manager U1 is connected to one end of capacitors C1 and C2 and then connected to a 5V power supply voltage. The other ends of capacitors C1 and C2 are connected to ground. Pin 2 of the power manager U1 is grounded. Pin 1 of the power manager U1 is connected to one end of capacitors C3 and C4 and pin 1 of the USB 2.0 connector. The other ends of capacitors C3 and C4 are grounded.

4. The USB signal overvoltage protection circuit of claim 2, wherein: The logic drive module includes resistors R5 and R6, MOSFETs Q1 and Q2, and a transient voltage suppressor D2. The transient voltage suppressor D2 is a BV-SRV05-4A_C-1 chip. Pins 1 and 6 of the transient voltage suppressor D2 are connected to the signal terminals USB2_DN and USB2_DP, respectively. Pin 2 of the transient voltage suppressor D2 is grounded. The I / O2 pin of the MCU microcontroller is connected to one end of resistor R6 and the gate of MOSFET Q2. The other end of resistor R6 is grounded. The drain of MOSFET Q2 is connected to one end of resistor R5 and the gate of MOSFET Q1. The sources of MOSFETs Q1 and Q2 are both grounded. The other end of resistor R5 is connected to a 5V power supply. The drain of MOSFET Q1 is connected to pin 5 of the transient voltage suppressor D2.

5. The USB signal overvoltage protection circuit of claim 1, wherein: The signal voltages of the USB2_DN and USB2_DP signal terminals are 0 to 3.3V. When the protection control module detects that the signal voltage exceeds 3.3V, it outputs a corresponding signal to the voltage control module and the logic drive module to perform protection actions.

6. The USB signal overvoltage protection circuit of claim 1, wherein: In the event of an overvoltage condition, the signal voltage of the USB2_DN or USB2_DP terminal is clamped to 0.7V.

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