USB interface protection circuit

Abstract

The utility model provides a USB interface protection circuit, including: common mode rejection circuit, filter circuit, ESD protection circuit wherein the common mode rejection circuit is connected between a first USB interface and a second USB interface, the filter circuit is connected between the common mode rejection circuit and the first USB interface, and the ESD protection circuit is also connected between the common mode rejection circuit and the first USB interface. According to the utility model, the common-mode inductor is additionally arranged in the differential wire for filtering, so that the common-mode current can be inhibited, the external radiation can be reduced, and the electromagnetic compatibility (EMC) problem can be reduced. The USB port is provided with over-current protection, ESD (electrostatic discharge) protection and a proper filter circuit, so that stable data transmission is ensured.

Description

Technical Field

[0001] This application relates to the technical field of USB interface protection, and in particular, to a USB interface protection circuit. Background Art

[0002] Differential transmission is a signal transmission technology. Different from the traditional method of using one signal line and one ground line, differential transmission transmits signals on both of these two lines. The amplitudes of these two signals are equal, the phases differ by 180 degrees, and the polarities are opposite. The signals transmitted on these two lines are differential signals. The USB interface adopts the form of differential signals.

[0003] Currently, problems such as common-mode current and static electricity are likely to occur in USB interfaces. Summary of the Utility Model

[0004] The purpose of the present utility model is achieved through the following technical solutions.

[0005] Specifically, the present utility model provides a USB interface protection circuit, including:

[0006] A common-mode rejection circuit, a filtering circuit, and an ESD protection circuit. The common-mode rejection circuit is connected between a first USB interface and a second USB interface. The filtering circuit is connected between the common-mode rejection circuit and the first USB interface. The ESD protection circuit is also connected between the common-mode rejection circuit and the first USB interface.

[0007] Further, the common-mode rejection circuit includes a common-mode inductor, two filtering capacitors, and two resistors.

[0008] Further, among the two resistors, the first resistor is connected between the USBD- pin of the second USB interface and the fourth port of the common-mode inductor, and the second resistor is connected between the USBD+ pin of the second USB interface and the first port of the common-mode inductor.

[0009] Further, among the two filtering capacitors, the first capacitor is connected between the fourth port of the common-mode inductor and the VSS pin of the second USB interface, and the second capacitor is connected between the first port of the common-mode inductor and the VSS pin of the second USB interface.

[0010] Further, the filtering circuit includes two capacitors. Among them, the third capacitor is connected between the D- pin of the first USB interface and the ground, and the fourth capacitor is connected between the D+ pin of the first USB interface and the ground.

[0011] Further, the ESD protection circuit includes two TVS diodes. Among them, the first TVS diode is connected between the D- pin of the first USB interface and the ground, and the second TVS diode is connected between the D+ pin of the first USB interface and the ground.

[0012] Furthermore, the USB interface protection circuit further includes a power filtering circuit and a common-mode rejection capacitor.

[0013] Furthermore, the power filtering circuit includes three filtering capacitors and a magnetic bead.

[0014] Furthermore, among the three filtering capacitors, the fifth capacitor and the sixth capacitor are connected in parallel between the USB5Vin pin of the second USB interface and the ground, the magnetic bead is connected between the USB5Vin pin of the second USB interface and the 5V pin of the first USB interface, and the seventh capacitor is connected between the 5V pin of the first USB interface and the ground.

[0015] Furthermore, the common-mode rejection capacitor is connected between the VSS pin of the second USB interface and the ground terminal of the first USB interface.

[0016] The advantages of the present utility model are as follows:

[0017] In the differential trace of the present utility model, a common-mode inductor is added for filtering, which can suppress the common-mode current, reduce the external radiation, and reduce the electromagnetic compatibility (EMC) problem. The USB port has overcurrent protection, ESD (electrostatic discharge) protection, and a suitable filtering circuit to ensure stable data transmission. Description of the Drawings

[0018] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered as a limitation of the present utility model. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0019] Figure 1 The overall architecture diagram according to the embodiment of the present utility model is shown.

[0020] Figure 2 It is the circuit diagram of the USB interface protection of the present utility model. Detailed Embodiments

[0021] Hereinafter, the exemplary embodiments of the present disclosure will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0022] As Figure 1As shown in the figure, the USB interface protection circuit of the present utility model includes: a common-mode rejection circuit, a filtering circuit, and an ESD protection circuit. Preferably, it may further include a power filtering circuit and a common-mode rejection capacitor. The common-mode rejection circuit is connected between the first USB interface (USB1) and the second USB interface (USB2). The filtering circuit is connected between the common-mode rejection circuit and the first USB interface. The ESD protection circuit is also connected between the common-mode rejection circuit and the first USB interface.

[0023] As Figure 2 shown, the common-mode rejection circuit includes a common-mode inductor T1, two filtering capacitors C1, C2, two resistors R1 and R2.

[0024] The filtering circuit includes two capacitors C3 and C4, which are respectively connected to the D+ and D- pins of the first USB interface.

[0025] The ESD protection circuit includes two TVS diodes, which are respectively connected to the D+ and D- pins of the first USB interface.

[0026] The power filtering circuit includes three filtering capacitors C5, C6, C7, and a magnetic bead L1.

[0027] The common-mode rejection capacitor C8 is connected between the VSS pin of the second USB interface and the ground terminal of the first USB interface.

[0028] The present utility model adds a common-mode inductor in the differential trace for filtering, which can suppress the common-mode current, reduce the external radiation, and reduce the electromagnetic compatibility (EMC) problems.

[0029] In the design considering EMC, the USB port needs to have overcurrent protection, ESD (electrostatic discharge) protection, and a suitable filtering circuit to ensure stable data transmission.

[0030] As Figure 2 shown, TVS1 and TVS2 are ESD protection diodes, which provide ESD discharge function to prevent damage to the circuit caused by hot plugging. Among them, TVS1 is connected between the D- pin of the first USB interface and the ground, and TVS2 is connected between the D+ pin of the first USB interface and the ground.

[0031] C1 and C2 are filtering capacitors. C1 is connected between the fourth port of the common-mode inductor and the VSS pin of the second USB interface, and C2 is connected between the first port of the common-mode inductor and the VSS pin of the second USB interface.

[0032] C3 is connected between the D- pin of the first USB interface and the ground, and C4 is connected between the D+ pin of the first USB interface and the ground.

[0033] C5, C6, and C7 are filter capacitors. L1 is a bead that can filter high-frequency noise and interference on the power supply. C5 and C6 are connected in parallel between the USB5Vin pin of the second USB interface and the ground. The bead is connected between the USB5Vin pin of the second USB interface and the 5V pin of the first USB interface. C7 is connected between the 5V pin of the first USB interface and the ground.

[0034] T1 is a common-mode inductor. The common-mode choke it has essentially resists the change in magnetic flux, that is, it plays a role in suppressing common-mode current and achieves the effect of filtering common-mode interference on differential lines. At the same time, the larger the inductance, the stronger the suppression effect.

[0035] R1 and R2 are protection resistors. R1 is connected between the USBD- pin of the second USB interface and the fourth port of the common-mode inductor. R2 is connected between the USBD+ pin of the second USB interface and the first port of the common-mode inductor.

[0036] C8 is a safety capacitor connected across VSS and GND. As an isolation device, it serves the purpose of suppressing common-mode interference.

[0037] As described above, it is only the preferred specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present utility model should be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. A USB interface protection circuit, characterized in that, Including: A common-mode rejection circuit, a filtering circuit, and an ESD protection circuit. The common-mode rejection circuit is connected between the first USB interface and the second USB interface. The filtering circuit is connected between the common-mode rejection circuit and the first USB interface. The ESD protection circuit is also connected between the common-mode rejection circuit and the first USB interface.

2. The USB interface protection circuit according to claim 1, characterized in that The common-mode rejection circuit includes a common-mode inductor, two filtering capacitors, and two resistors.

3. The USB interface protection circuit according to claim 2, characterized in that Among the two resistors, the first resistor is connected between the USBD- pin of the second USB interface and the fourth port of the common-mode inductor, and the second resistor is connected between the USBD+ pin of the second USB interface and the first port of the common-mode inductor.

4. The USB interface protection circuit according to claim 2, characterized in that Among the two filtering capacitors, the first capacitor is connected between the fourth port of the common-mode inductor and the VSS pin of the second USB interface, and the second capacitor is connected between the first port of the common-mode inductor and the VSS pin of the second USB interface.

5. The USB interface protection circuit according to claim 1, characterized in that The filtering circuit includes two capacitors. Among them, the third capacitor is connected between the D- pin of the first USB interface and the ground, and the fourth capacitor is connected between the D+ pin of the first USB interface and the ground.

6. The USB interface protection circuit according to claim 1, characterized in that The ESD protection circuit includes two TVS diodes. Among them, the first TVS diode is connected between the D- pin of the first USB interface and the ground, and the second TVS diode is connected between the D+ pin of the first USB interface and the ground.

7. The USB interface protection circuit according to claim 1, characterized in that The USB interface protection circuit further includes a power filtering circuit and a common-mode rejection capacitor.

8. The USB interface protection circuit according to claim 7, characterized in that The power filtering circuit includes three filtering capacitors and a magnetic bead.

9. The USB interface protection circuit according to claim 8, characterized in that Among the three filtering capacitors, the fifth capacitor and the sixth capacitor are connected in parallel between the USB5Vin pin of the second USB interface and the ground. The magnetic bead is connected between the USB5Vin pin of the second USB interface and the 5V pin of the first USB interface. The seventh capacitor is connected between the 5V pin of the first USB interface and the ground.

10. The USB interface protection circuit according to claim 7, characterized in that The common-mode rejection capacitor is connected between the VSS pin of the second USB interface and the ground terminal of the first USB interface.

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