USB interface circuit for computer

Abstract

The utility model relates to the technical field of computers, in particular to a USB (Universal Serial Bus) interface circuit for a computer, which comprises a noise reduction circuit, a signal processing circuit, a signal processing circuit, a signal processing circuit, a signal processing circuit, a signal processing circuit, a signal processing circuit and a signal processing circuit, and is characterized in that the noise reduction circuit comprises a forward signal noise reduction circuit and a reverse signal noise reduction circuit, the forward signal noise reduction circuit is connected with a D + pin of a USB chip; the reverse signal noise reduction circuit is connected with a D-pin of the USB chip; the comparison circuit comprises a first operational amplifier A1, the in-phase input section of the first operational amplifier A1 is connected with the VBUS pin, the in-phase input end of the first operational amplifier A1 is connected with the power supply, and the output end of the first operational amplifier A1 is connected with the MCU; and the temperature detection circuit is connected with the MCU and is used for transmitting the digital signal to the MCU. An MCU; and the control switch is a switch of a VBUS line and is used for receiving the control level signal output by the MCU.

Description

Technical Field

[0001] The utility model relates to the technical field of computers, and in particular to a USB interface circuit for a computer. Background Art

[0002] At present, the front USB interface of the computer has become one of the standard features of modern computer cases. Through the front USB, the computer can more conveniently connect various external devices, such as flash drives, keyboards, mice, cameras, etc., without having to find interfaces on the back of the case, thereby increasing user convenience and operational flexibility, and also meeting the modern people's demand for convenient device connection.

[0003] As computer peripherals are constantly updated and upgraded, their functions are constantly increasing and optimized, and the power consumption per unit time is also increasing. Therefore, USB interface output overload occurs from time to time. USB interface output overload may cause the electronic components in the USB interface circuit or external devices to overheat, be damaged or even fail, and the insulation layer of some electronic components or themselves may also be broken down. Utility Model Content

[0004] In order to solve the problem of output overload that may occur through the USB interface, the utility model proposes a USB interface circuit for a computer. To this end, the utility model provides the following solutions.

[0005] A USB interface circuit for a computer includes: a noise reduction circuit, which includes a forward signal noise reduction circuit and a reverse signal noise reduction circuit, the forward signal noise reduction circuit is connected to the D+ pin of a USB chip, and the reverse signal noise reduction circuit is connected to the D- pin of the USB chip; a comparison circuit, which is connected to the VBUS pin of the USB chip and is used to compare the magnitude of the VBUS output voltage with the standard voltage; a temperature detection circuit, which is connected to the MCU and is used to convert the temperature of the USB interface into a digital signal and transmit the digital signal to the MCU. The MCU receives the result of the comparison between the magnitude of the VBUS output voltage and the standard voltage, and inputs a control level signal to the control switch according to the result; the control switch is a switch of the VBUS line, and receives the control level signal output by the MCU, and controls the connection and disconnection of the USB power output line according to the control level signal.

[0006] In one embodiment, the comparison circuit includes a first inductor L1, a second resistor R2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a first operational amplifier A1, the non-inverting input terminal of the first operational amplifier A1 is connected to the VBUS pin through the second resistor R2 and the first inductor L1, the inverting input terminal of the first operational amplifier A1 is connected to the power supply through the seventh resistor R7, and the two ends of the eighth resistor R8 are respectively connected to the non-inverting input terminal and the output terminal of the first operational amplifier A1, thereby forming a negative feedback loop, and the output terminal of the first operational amplifier A1 is also connected to the MCU.

[0007] In one embodiment, the forward signal noise reduction circuit includes: a third inductor L3, a first capacitor C1 and a fourth resistor R4, one pole of the first capacitor C1 is connected to the D+ pin of the USB chip through the fourth resistor R4 and the third inductor L3, and the other pole of the first capacitor C1 is grounded, wherein the third inductor L3 is a magnetic core inductor.

[0008] In one embodiment, the reverse signal noise reduction circuit includes: a second inductor L2, a second capacitor C2 and a third resistor R3, one pole of the second capacitor C2 is connected to the D-pin of the USB chip through the third resistor R3 and the second inductor L2, and the other pole of the second capacitor C2 is grounded, wherein the second inductor L2 is a magnetic core inductor.

[0009] In one embodiment, the temperature detection circuit includes: a thermistor Rntc, a signal amplifier, a thirteenth resistor R13, a fourteenth resistor R14 and a third capacitor C3, one end of the thermistor Rntc is grounded, the other end of the thermistor Rntc is connected to the power supply through the thirteenth resistor R13, the other end of the thermistor Rntc is also connected to the signal amplifier through the fourteenth resistor R14, one end of the signal amplifier connected to the fourteenth resistor R14 is also grounded C3 through the third capacitor, the signal amplifier is connected to the MCU, wherein the thermistor is installed inside the metal shell of the USB interface.

[0010] In one embodiment, the signal amplifier includes a second operational amplifier A2, a fifteenth resistor R15, and a sixteenth resistor R16, the non-inverting input terminal of the second operational amplifier A2 is connected to the compensator, the inverting input terminal of the second operational amplifier A2 is grounded through the fifteenth resistor R15, the inverting input terminal of the second operational amplifier A2 is also connected to the output terminal of the second operational amplifier A2 through the sixteenth resistor R16, and the output terminal of the second operational amplifier A2 is also connected to the MCU.

[0011] In one embodiment, the signal amplifier is connected to the MCU via an ADC conversion circuit.

[0012] In one embodiment, the control switch includes a transistor Q, a tenth resistor R10, an eleventh resistor R1 and a twelfth resistor R12, one end of the tenth resistor R10 and the emitter of the transistor Q are connected to the ninth resistor R9, the base of the transistor Q is connected to the other end of the tenth resistor R10, the base of the transistor Q is also connected to the MCU through the eleventh resistor R1, and the collector of the transistor becomes the power output end of the USB interface circuit through the twelfth resistor R12.

[0013] In one embodiment, the emitter of the transistor Q is also connected to the VBUS pin through the ninth resistor R9 and the first inductor L1.

[0014] In one embodiment, a USB interface circuit for a computer further includes a fourth inductor L4 and a first resistor R1, and a GND pin of a USB chip is grounded through the fourth inductor L4, and a D+ pin of the USB chip is connected to a power supply through the first resistor R1, wherein the first resistor R1 is a pull-up resistor.

[0015] The beneficial effects of the utility model are:

[0016] The utility model compares the actual output voltage of the computer USB interface with the voltage of a power supply, and disconnects the power line between the computer USB interface and the external device when the actual output voltage of the USB interface is greater than the voltage of the power supply. The utility model also obtains the temperature of the USB interface through a temperature detection circuit, and when the temperature of the USB interface exceeds a preset temperature threshold, the USB power line is disconnected when the MCU sends a control signal.

[0017] The utility model detects the actual output voltage of the USB interface and the temperature of the USB interface, and controls the conduction or disconnection of the power line of the USB interface according to the detection result, thereby preventing the USB line from being damaged due to overload or excessive voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present invention will become easy to understand. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0019] Figure 1 A USB interface circuit for a computer according to an embodiment of the present invention;

[0020] Figure 2is a circuit for controlling a switch according to an embodiment of the present invention;

[0021] Figure 3 Detailed description of the invention The temperature detection circuit according to the embodiment of the invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0023] The specific implementation of the utility model is described in detail below with reference to the accompanying drawings.

[0024] Figure 1 The present invention discloses a USB interface circuit for a computer according to an embodiment of the present invention.

[0025] like Figure 1 As shown, a USB interface circuit for a computer includes: a noise reduction circuit, which includes a forward signal noise reduction circuit and a reverse signal noise reduction circuit, the forward signal noise reduction circuit is connected to the D+ pin of the USB chip, and the reverse signal noise reduction circuit is connected to the D- pin of the USB chip; a comparison circuit, which is connected to the VBUS pin of the USB chip, and is used to compare the VBUS output voltage with the standard voltage; a temperature detection circuit, which is connected to the MCU, and is used to convert the temperature of the USB interface into a digital signal, and transmit the digital signal to the MCU. The MCU receives the result of the comparison between the VBUS output voltage and the standard voltage, and inputs a control level signal to the control switch according to the result; the control switch is a switch of the VBUS line, and receives the control level signal output by the MCU, and controls the connection and disconnection of the USB power output line according to the control level signal.

[0026] The model of the USB chip is DS2490S. DS2490S is a USB to 1-Wire interface chip. Through the DS2490S chip, the computer can read and write devices (such as temperature sensors, EEPROM memories) connected to the 1-Wire bus. DS2490S also has the advantages of high-speed communication, multi-device support, low power consumption and easy integration, and is suitable for various applications such as smart meters, automation control, temperature monitoring, etc.

[0027] Furthermore, the comparison circuit compares the voltage output by the VBUS pin with the voltage of the power supply through a comparator (comparison circuit), and transmits the comparison result to the MCU in the form of an analog signal. After the MCU processes the signal, it sends a control signal to the control circuit, thereby realizing the on and off of the VBUS line according to the voltage output by the VBUS pin of the USB interface. When the voltage output by the VBUS pin is less than the standard voltage, the VBUS line is turned on; when the voltage output by the VBUS pin is greater than the standard voltage, the VBUS line is disconnected.

[0028] Furthermore, a USB interface circuit for a computer further includes a fourth inductor L4 and a first resistor R1, and the GND pin of the USB chip is grounded through the fourth inductor L4, thereby prohibiting high-frequency interference and reducing EMI (Electromagnetic Interference) radiation. The D+ pin of the USB chip is connected to the power supply through the first resistor R1, and the first resistor is connected to the power supply, so that the signal of the positive signal line in the differential signal line is pulled to a logic high level. The power supply is a standard power supply, and its voltage is usually 5V.

[0029] In one embodiment, the comparison circuit includes a first inductor L1, a second resistor R2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a first operational amplifier A1, the non-inverting input terminal of the first operational amplifier A1 is connected to the VBUS pin through the second resistor R2 and the first inductor L1, the inverting input terminal of the first operational amplifier A1 is connected to the power supply through the seventh resistor R7, and the two ends of the eighth resistor R8 are respectively connected to the non-inverting input terminal and the output terminal of the first operational amplifier A1, thereby forming a negative feedback loop, and the output terminal of the first operational amplifier A1 is also connected to the MCU.

[0030] When the output terminal of the first operational amplifier A1 outputs a low-level signal, it indicates that the output voltage of the VBUS line is higher than the standard voltage, and the control switch needs to be turned off. When the output terminal of the first operational amplifier A1 outputs a high-level signal, it indicates that the output voltage of the VBUS line is lower than the standard voltage, and the control switch needs to be turned on.

[0031] In one embodiment, the forward signal noise reduction circuit includes: a third inductor L3, a first capacitor C1 and a fourth resistor R4, one electrode of the first capacitor C1 is connected to the D+ pin of the USB chip through the fourth resistor R4 and the third inductor L3, and the other electrode of the first capacitor C1 is grounded. The third inductor L3, the first capacitor C1 and the fourth resistor R4 constitute a filter to filter the forward signal in the differential signal so that the noise in the signal is filtered out. The fourth resistor R4 is used to protect the circuit.

[0032] In one embodiment, the reverse signal noise reduction circuit includes: a second inductor L2, a second capacitor C2 and a third resistor R3, one electrode of the second capacitor C2 is connected to the D-pin of the USB chip through the third resistor R3 and the second inductor L2, and the other electrode of the second capacitor C2 is grounded. The second inductor L2, the second capacitor C2 and the third resistor R3 form a filter to filter the reverse signal in the differential signal so that the noise in the signal is filtered out. The third resistor R3 is used to protect the circuit.

[0033] Figure 2 Detailed description of the invention The invention is a circuit for controlling a switch according to an embodiment of the invention.

[0034] like Figure 2 As shown, the control switch includes a transistor Q, a tenth resistor R10, an eleventh resistor R1 and a twelfth resistor R12.

[0035] Among them, one end of the tenth resistor R10 and the emitter of the transistor Q are connected to the ninth resistor R9, the base of the transistor Q is connected to the other end of the tenth resistor R10, the base of the transistor Q is also connected to the MCU through the eleventh resistor R1, and the collector of the transistor becomes the power output end of the USB interface circuit through the twelfth resistor R12.

[0036] In particular, the transistor plays a role of switch control in the circuit, while the ninth resistor R9 and the tenth resistor R10 play a role of current limiting, and the twelfth resistor R12 limits the output current. The current flowing through the eleventh resistor R1 controls the working state of the transistor Q, thereby realizing the control of the output current of the USB interface circuit.

[0037] In one embodiment, the transistor Q is an NPN transistor. The NPN transistor has three differently doped semiconductor regions, forming two PN junctions. The N-type substrate is sandwiched between two P-type regions, forming two PN junctions. The emitter is connected to the P-type region, and the collector is connected to the N-type region. In this embodiment, the NPN transistor is used as a switch. When the base current of the transistor Q is large enough, the transistor Q is in a saturation state, and a low impedance path is formed between the collector and the emitter, which is equivalent to a closed switch; when the base current is small or zero, the transistor Q is in a cut-off state, which is equivalent to a switch disconnected. And according to the control signal output by the MCU, the transistor Q can be in a saturation or cut-off state, thereby realizing the control of the circuit.

[0038] Figure 3 Detailed description of the invention The temperature detection circuit according to the embodiment of the invention.

[0039] like Figure 3As shown, in one embodiment, the temperature detection circuit includes: a thermistor Rntc, a signal amplifier, a thirteenth resistor R13, a fourteenth resistor R14 and a third capacitor C3, one end of the thermistor Rntc is grounded, the other end of the thermistor Rntc is connected to the power supply through the thirteenth resistor R13, the other end of the thermistor Rntc is also connected to the signal amplifier through the fourteenth resistor R14, one end of the signal amplifier connected to the fourteenth resistor R14 is also grounded C3 through the third capacitor, and the signal amplifier is connected to the MCU.

[0040] In one embodiment, the signal amplifier includes a second operational amplifier A2, a fifteenth resistor R15, and a sixteenth resistor R16, the non-inverting input terminal of the second operational amplifier A2 is connected to the compensator, the inverting input terminal of the second operational amplifier A2 is grounded through the fifteenth resistor R15, the inverting input terminal of the second operational amplifier A2 is also connected to the output terminal of the second operational amplifier A2 through the sixteenth resistor R16, and the output terminal of the second operational amplifier A2 is also connected to the MCU.

[0041] Furthermore, one end of the sixteenth resistor R16 connected to the signal amplifier is also grounded through the third capacitor C3. The third capacitor C3 is used to filter out high-frequency noise in the compensator output signal to ensure signal purity and reliability. The capacitor C3 can also isolate electromagnetic interference between the compensator and the ground, thereby improving signal stability and anti-interference capability.

[0042] In one embodiment, the signal amplifier includes a third operational amplifier A3, a seventeenth resistor R17, and an eighteenth resistor R18, the non-inverting input terminal of the third operational amplifier A3 is connected to the compensator, the inverting input terminal of the third operational amplifier A3 is grounded through the seventeenth resistor R17, the inverting input terminal of the third operational amplifier A3 is also connected to the output terminal of the third operational amplifier A3 through the eighteenth resistor R18, and the output terminal of the third operational amplifier A3 is also connected to the MCU.

[0043] Furthermore, the signal amplifier is connected to the MCU through the ADC conversion circuit, thereby converting the amplified signal into a digital signal for digital processing and analysis by the MCU. After the MCU processes the digital signal, it obtains the temperature of the USB interface, and then compares the measured temperature with the preset temperature threshold. When the temperature of the USB interface is too high, the MCU sends a control signal to the control switch to disconnect the VBUS line.

[0044] In the above description of this specification, unless otherwise clearly specified and limited, the terms "fixed", "installed", "connected" or "connected" should be understood in a broad sense. For example, with regard to the term "connection", it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. Therefore, unless otherwise clearly defined in this specification, those skilled in the art can understand the specific meanings of the above terms in this utility model according to the specific circumstances.

[0045] In addition, the terms "first" or "second" used in this specification to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this specification, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0046] Although this specification has shown and described a plurality of embodiments of the utility model, it is obvious to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will think of many changes, modifications and alternatives without departing from the idea and spirit of the utility model. It should be understood that in the process of practicing the utility model, various alternatives to the embodiments of the utility model described herein may be adopted. The attached claims are intended to define the scope of protection of the utility model, and therefore cover the modular composition, equivalent or alternatives within the scope of these claims.

Claims

1. A USB interface circuit for a computer, characterized in that: include: A noise reduction circuit, comprising a forward signal noise reduction circuit and a reverse signal noise reduction circuit, wherein the forward signal noise reduction circuit is connected to the D+ pin of the USB chip, and the reverse signal noise reduction circuit is connected to the D- pin of the USB chip; A comparison circuit is connected to the VBUS pin of the USB chip and is used to compare the VBUS output voltage with the standard voltage; A temperature detection circuit is connected to the MCU and is used to convert the temperature of the USB interface into a digital signal and transmit the digital signal to the MCU; MCU, which receives the result of comparing the VBUS output voltage with the standard voltage, and inputs a control level signal to the control switch according to the result; The control switch is a switch of the VBUS line, and receives the control level signal output by the MCU, and controls the connection and disconnection of the USB power output line according to the control level signal.

2. A USB interface circuit for a computer according to claim 1, characterized in that: The comparison circuit comprises: a first inductor (L1), a second resistor (R2), a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8) and a first operational amplifier (A1); a non-inverting input terminal of the first operational amplifier (A1) is connected to the VBUS pin through the second resistor (R2) and the first inductor (L1); an inverting input terminal of the first operational amplifier (A1) is connected to the power supply through the seventh resistor (R7); two ends of the eighth resistor (R8) are respectively connected to the non-inverting input terminal and the output terminal of the first operational amplifier (A1), thereby forming a negative feedback loop; and the output terminal of the first operational amplifier (A1) is also connected to the MCU.

3. A USB interface circuit for a computer according to claim 1, characterized in that: The forward signal noise reduction circuit comprises: a third inductor (L3), a first capacitor (C1) and a fourth resistor (R4), one pole of the first capacitor (C1) is connected to the D+ pin of the USB chip through the fourth resistor (R4) and the third inductor (L3), and the other pole of the first capacitor (C1) is grounded, wherein the third inductor (L3) is a magnetic core inductor.

4. A USB interface circuit for a computer according to claim 1, characterized in that: The reverse signal noise reduction circuit comprises: a second inductor (L2), a second capacitor (C2) and a third resistor (R3), one pole of the second capacitor (C2) is connected to the D-pin of the USB chip through the third resistor (R3) and the second inductor (L2), and the other pole of the second capacitor (C2) is grounded, wherein the second inductor (L2) is a magnetic core inductor.

5. A USB interface circuit for a computer according to claim 1, characterized in that: The temperature detection circuit includes: a thermistor (Rntc), a signal amplifier, a thirteenth resistor (R13), a fourteenth resistor (R14) and a third capacitor (C3), one end of the thermistor (Rntc) is grounded, the other end of the thermistor (Rntc) is connected to a power supply through the thirteenth resistor (R13), the other end of the thermistor (Rntc) is also connected to the signal amplifier through the fourteenth resistor (R14), one end of the signal amplifier connected to the fourteenth resistor (R14) is also grounded through the third capacitor (C3), the signal amplifier is connected to the MCU, wherein the thermistor is installed inside a metal shell of a USB interface.

6. A USB interface circuit for a computer according to claim 5, characterized in that: The signal amplifier comprises a second operational amplifier (A2), a fifteenth resistor (R15), and a sixteenth resistor (R16); the non-inverting input terminal of the second operational amplifier (A2) is connected to the compensator; the inverting input terminal of the second operational amplifier (A2) is grounded through the fifteenth resistor (R15); the inverting input terminal of the second operational amplifier (A2) is also connected to the output terminal of the second operational amplifier (A2) through the sixteenth resistor (R16); and the output terminal of the second operational amplifier (A2) is also connected to the MCU.

7. A USB interface circuit for a computer according to claim 5, characterized in that: The signal amplifier is connected to the MCU via an ADC conversion circuit.

8. A USB interface circuit for a computer according to claim 1, characterized in that: The control switch comprises: a transistor (Q), a tenth resistor (R10), an eleventh resistor (R1) and a twelfth resistor (R12), one end of the tenth resistor (R10) and the emitter of the transistor (Q) are connected to the ninth resistor (R9), the base of the transistor (Q) is connected to the other end of the tenth resistor (R10), the base of the transistor (Q) is also connected to the MCU through the eleventh resistor (R1), and the collector of the transistor becomes the power output end of the USB interface circuit through the twelfth resistor (R12).

9. A USB interface circuit for a computer according to claim 8, characterized in that: The emitter of the transistor (Q) is also connected to the VBUS pin through the ninth resistor (R9) and the first inductor (L1).

10. A USB interface circuit for a computer according to claim 1, characterized in that: Also includes: A fourth inductor (L4) and a first resistor (R1), and a GND pin of the USB chip is grounded through the fourth inductor (L4), and a D+ pin of the USB chip is connected to a power source through the first resistor (R1), wherein the first resistor (R1) is a pull-up resistor.

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