CN220254480U

CN220254480U - Protection filter circuit of USB2.0 interface

Info

Publication number: CN220254480U
Application number: CN202321565230.3U
Authority: CN
Inventors: 李嘉林; 刘晟; 谢敏钊; 李伟涛
Original assignee: Shenzhen Top Flight Technology Co ltd
Current assignee: Shenzhen Top Flight Technology Co ltd
Priority date: 2023-06-19
Filing date: 2023-06-19
Publication date: 2023-12-26
Anticipated expiration: 2033-06-19

Abstract

The utility model discloses a protection filter circuit of a USB2.0 interface, which belongs to the technical field of USB interfaces and comprises the following three circuits: the first circuit is a protection circuit formed by a transient voltage suppressor. The second circuit is a filter circuit formed by a two-wire balance filter on the D+ and D-differential lines. And the third circuit is a filter circuit formed by a double-wire balance filter I on a power line of the power supply line. Compared with the traditional scheme of adding the common mode filter to the differential line of the differential signal line, the protection filter circuit has the advantages that the common mode filter is replaced by only one double-line balance filter, so that the cost is reduced, the filtering effect is better, and for the power line of the power supply line, the common filter circuit with two capacitors matched with one magnetic bead is replaced by only one double-line balance filter, the circuit design is simplified, and the use space of the PCB is optimized.

Description

Protection filter circuit of USB2.0 interface

Technical Field

The utility model relates to the technical field of USB interfaces, in particular to a protection filter circuit of a USB2.0 interface.

Background

With the development of the world industry level, the requirements on electromagnetic compatibility equipment and application technology are higher and higher, and the requirements are increasing. Electromagnetic compatibility has been widely used in a variety of fields and is increasingly highly appreciated by people. The electromagnetic compatibility standard authentication has been developed worldwide from a national scope, so that the electromagnetic compatibility is in the same importance as the safety and the environmental adaptability.

Electromagnetic compatibility refers to the ability of electronic devices to function properly in an electromagnetic environment, and electromagnetic interference is a phenomenon of electromagnetic variation detrimental to the performance of electronic devices. The electronic equipment needs to work normally when receiving surrounding electromagnetic interference, and the electronic equipment does not generate electromagnetic interference to other surrounding equipment, so that the normal operation of other equipment is affected.

As the USB2.0 interface is widely used in most electronic products, the problem of electromagnetic compatibility is more important, and the influence on the normal operation of other electronic products and the normal operation of the USB2.0 interface are avoided. Besides the electrostatic protection, the internal circuit of the USB2.0 interface is subjected to filtering treatment, because the transmission rate of the USB2.0 interface is very high, if the filtering circuit module is not added, the internal circuit is easily affected by external electromagnetic interference, thereby causing abnormal operation of the interface.

At present, the filtering scheme of the prior art of the USB2.0 interface cannot filter GHz upwards, and a plurality of filtering devices are added in the scheme, so that a relatively large space is occupied, and the application provides a protection filtering circuit of the USB2.0 interface.

Disclosure of Invention

The utility model aims to provide a protection filter circuit of a USB2.0 interface, which has a simple structure, compared with the scheme of adding a common mode filter to a differential line of a pair of differential signal lines, the scheme uses only one double-line balance filter to replace the common mode filter, thereby reducing the cost, having better filtering effect.

In order to achieve the above purpose, the present utility model provides the following technical solutions: a protection filter circuit of a USB2.0 interface comprises the following three circuits:

the first circuit is a protection circuit formed by a transient voltage suppressor.

The second circuit is a filter circuit formed by a first double-line balance filter on D+ and D-differential lines.

The third circuit is a filter circuit formed by a double-wire balance filter I on a power line of the power supply line.

As a further scheme of the utility model: the first circuit consists of a first transient voltage suppressor, a second transient voltage suppressor and three transient voltage suppressors, wherein the transient voltage suppressors are devices at two ends, one end of each transient voltage suppressor is connected to a power supply circuit and a pair of differential signal wires, and the other end of each transient voltage suppressor is connected to the upper surface of a working floor. The electrostatic interference can be released rapidly, and the phenomenon that the internal circuit works abnormally due to the fact that a large amount of interference energy generated in the hot plug process impacts the circuit is avoided.

As still further aspects of the utility model: the circuit II consists of a double-line balance filter II, a traditional USB2.0 differential signal line filter circuit is only provided with a common mode filter, electromagnetic interference still exists in a frequency band higher than 300MHz upwards, filtering is incomplete, the circuit introduces the double-line balance filter II to carry out full-frequency band filtering, the double-line balance filter II is a four-terminal device, two ends of the double-line balance filter II are respectively connected to D-, D+ signal lines, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground.

As still further aspects of the utility model: the circuit III is composed of a double-wire balance filter III which is a four-terminal device, wherein two ends of A, B are respectively connected to a power supply circuit and a circuit board line, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground. Different from the common filter circuit with two capacitors matched with one magnetic bead on the power line of the power supply line, the filter circuit formed by the single two-wire balance filter is space-saving, cost-saving and wider in filter frequency band.

Compared with the prior art, the utility model has the beneficial effects that: compared with the traditional scheme of adding the common mode filter to the differential line of the differential signal line, the protection filter circuit has the advantages that the common mode filter is replaced by only one double-line balance filter, so that the cost is reduced, the filtering effect is better, and for the power line of the power supply line, the common filter circuit with two capacitors matched with one magnetic bead is replaced by only one double-line balance filter, the circuit design is simplified, and the use space of the PCB is optimized.

Compared with the traditional filtering scheme, the protection filtering circuit has extremely low ESL (parasitic inductance), can expand high-frequency filtering to a GHz range, has better filtering effect, and is internally integrated with two balance capacitor components, so that differential mode common mode conversion is effectively reduced, and EMC (electro magnetic compatibility) problems can be rapidly solved.

Drawings

FIG. 1 is a schematic diagram of the working principle of the protection filter circuit of the USB2.0 interface of the utility model;

FIG. 2 is a schematic diagram of the internal structure of a two-wire balanced filter according to the present utility model;

FIG. 3 is a schematic diagram of a USB2.0 interface circuit according to the present utility model;

FIG. 4 is a diagram illustrating a filtering operation of the USB2.0 interface circuit according to the present utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", "one end", "one side", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

The utility model aims to solve the technical problems that aiming at the USB2.0 interface which is widely used at present, the utility model provides a protection filter circuit which has pertinence to the USB2.0 interface, thereby achieving the purposes of reducing EMC test cost, optimizing circuit design and the like and leading the product to have better electromagnetic compatibility.

Referring to fig. 1 to 4, in an embodiment of the present utility model, a protection filter circuit of a USB2.0 interface includes three circuits as follows:

The second circuit is a filter circuit formed by a two-wire balance filter on the D+ and D-differential lines.

And the third circuit is a filter circuit formed by a double-wire balance filter I on a power line of the power supply line.

Preferably: the first transient voltage suppressor is a device with two ends, one end of the transient voltage suppressor is connected to the power supply line and the wires of a pair of differential signal wires respectively, and the other end of the transient voltage suppressor is connected to the upper surface of the working floor. The electrostatic interference can be released rapidly, and the phenomenon that the internal circuit works abnormally due to the fact that a large amount of interference energy generated in the hot plug process impacts the circuit is avoided.

Preferably: the second circuit is composed of a second double-line balance filter, a traditional USB2.0 differential signal line filter circuit is only provided with a common mode filter, electromagnetic interference exists in a frequency band higher than 300MHz upwards, filtering is incomplete, the second double-line balance filter is introduced to carry out full-frequency band filtering, the second double-line balance filter is a four-terminal device, two ends of the A, B are respectively connected to D-, D+ signal lines, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground.

The powerful filtering effect of the technical scheme benefits from the internal structure of the BDL filter, a Faraday shielding cage structure is arranged between the internal electrodes, the Faraday shielding cage structure is provided with two first reference electrodes and two second reference electrodes which are connected in parallel, and the two reference electrodes are cited for grounding treatment to form a first shielding electrode plate and a second shielding electrode plate. The above structural features creatively transform a single-ended component that is otherwise unbalanced into a double-ended balanced component, i.e., into a capacitor that is comprised of two nominally identical capacitors. FIG. 2 is an internal structural diagram of a BDL filter

Preferably: the third circuit is composed of a three-wire balance filter, the three-wire balance filter is a four-terminal device, two ends of A, B are respectively connected to a power supply line and a circuit board line, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground. Different from the common filter circuit with two capacitors matched with one magnetic bead on the power line of the power supply line, the filter circuit formed by the single two-wire balance filter is space-saving, cost-saving and wider in filter frequency band.

In this embodiment, the filter is a two-wire balanced filter.

The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should make equivalent substitutions or modifications according to the technical scheme of the present utility model and the inventive concept thereof, and should be covered by the scope of the present utility model.

Claims

1. The utility model provides a protection filter circuit of USB2.0 interface which characterized in that: the circuit comprises the following three circuits:

the first circuit is a protection circuit formed by a transient voltage suppressor;

the second circuit is a filter circuit formed by a first double-line balance filter on a D+ and D-differential line;

2. The protection filter circuit of a USB2.0 interface of claim 1, wherein: the first circuit consists of a first transient voltage suppressor, a second transient voltage suppressor and three transient voltage suppressors, wherein the transient voltage suppressors are devices at two ends, one end of each transient voltage suppressor is respectively connected to a power supply circuit and a pair of differential signal wires, the other end of each transient voltage suppressor is connected to the working ground, electrostatic interference can be rapidly released, and a large amount of interference energy generated in the hot plug process is prevented from impacting the circuit, so that the internal circuit works abnormally.

3. The protection filter circuit of a USB2.0 interface of claim 1, wherein: the circuit II consists of a double-line balance filter II, a traditional USB2.0 differential signal line filter circuit is only provided with a common mode filter, electromagnetic interference still exists in a frequency band higher than 300MHz upwards, filtering is incomplete, the circuit introduces the double-line balance filter II to carry out full-frequency band filtering, the double-line balance filter II is a four-terminal device, two ends of the double-line balance filter II are respectively connected to D-, D+ signal lines, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground.

4. The protection filter circuit of a USB2.0 interface of claim 1, wherein: the circuit III is composed of a double-wire balance filter III which is a four-terminal device, wherein two ends of A, B are respectively connected to a power supply circuit and a circuit board line, and two ends of a first terminal of the filter and two ends of a second terminal of the filter are connected with a metal shell ground.