Short circuit protection circuit, short circuit protection module, short circuit protection device and audio-video interface

Abstract

The utility model relates to the technical field of video signals, and discloses a short-circuit protection circuit, a module, a device and an audio-video interface, the short-circuit protection circuit is connected with an external test power supply, the short-circuit protection circuit comprises a control module, a first end of the control module is connected with the external test power supply, and a second end of the control module is connected with a second end of the control module; the control module is used for receiving a test voltage input by the external test power supply and outputting a turn-off signal; the first end of the switch module is connected to the external test power supply, the second end of the switch module is connected with the second end of the control module, the third end of the switch module is connected with a matched resistor, and the switch module is used for receiving the turn-off signal and stopping transmitting the test voltage to the matched resistor. Therefore, the matching resistor in the test process can be protected.

Description

Technical Field

[0001] The present application relates to the field of video signal technology, and in particular to a short protection circuit, a module, a device, and an audio-visual interface. Background Art

[0002] The impedance of the input end of the CVBS (Composite Video Broadcast Signal or Composite Video Blanking and Sync) signal connector is generally 75 ohms, and the corresponding resistor package is generally a maximum of 1206 / 0.25W, where 1206 is the package size and 0.25W is the rated power.

[0003] When the harness on the CVBS signal connector is tested by short-circuiting the power supply (12V or 24V) and the ground for one minute, that is, when the power is applied to the CVBS signal line, the 75-ohm matching resistor is at risk of damage because the power exceeds the limit value.

[0004] Application Contents

[0005] The main purpose of the present application is to provide a short protection circuit, module, device and audio-visual interface, aiming to solve the problem that the matching resistor is easily damaged during the short test of the CVBS signal.

[0006] To achieve the above object, the present application provides a short circuit protection circuit, the short circuit protection circuit is connected to an external test power supply, and the short circuit protection circuit includes:

[0007] A control module, a first end of which is connected to the external test power supply, and the control module is used to receive a test voltage input by the external test power supply and output a shutdown signal;

[0008] A switch module, wherein a first end of the switch module is connected to the external test power supply, a second end of the switch module is connected to a second end of the control module, a third end of the switch module is connected to a matching resistor, and the switch module is used to receive the shutdown signal to stop transmitting the test voltage to the matching resistor.

[0009] Optionally, the control module includes:

[0010] A voltage dividing unit, a first end of which is connected to a first end of the switch module;

[0011] A control unit, wherein a first end of the control unit is connected to a second end of the voltage dividing unit, and a second end of the control unit is connected to a second end of the switch module.

[0012] Optionally, the voltage dividing unit includes:

[0013] a first resistor, wherein a first end of the first resistor is connected to the external test power supply, and a second end of the first resistor is connected to a first end of the control unit;

[0014] A second resistor, wherein a first end of the second resistor is connected to a first end of the control unit, and a second end of the second resistor is grounded.

[0015] Optionally, the control unit comprises:

[0016] A transistor, wherein the first end of the transistor is connected to the second end of the first resistor, the second end of the transistor is respectively connected to a preset reference voltage and the second end of the switch module, and the third end of the transistor is grounded.

[0017] Optionally, the control unit further includes:

[0018] A third resistor, wherein a first end of the third resistor is connected to the preset reference voltage, and a second end of the third resistor is connected to the second end of the transistor.

[0019] Optionally, the switch module includes:

[0020] A field effect tube, wherein the first end of the field effect tube is connected to the signal input end, the second end of the field effect tube is respectively connected to the first end of the matching resistor and the signal output end, and the third end of the field effect tube is connected to the second end of the transistor.

[0021] Optionally, the switch module further includes:

[0022] A capacitor, wherein a first end of the capacitor is connected to a second end of the field effect tube, and a second end of the capacitor is used to output a signal.

[0023] In addition, to achieve the above-mentioned purpose, the present application provides a short circuit protection module, and the short circuit protection module includes the short circuit protection circuit as described above.

[0024] In addition, to achieve the above-mentioned purpose, the present application provides a short circuit protection device, which includes the short circuit protection module as described above.

[0025] In addition, to achieve the above-mentioned purpose, the present application provides an audio and video interface, and the audio and video interface includes the short-circuit protection device as described above.

[0026] The present application provides a short protection circuit, the short protection circuit is connected to an external test power supply, and the short protection circuit includes: a control module, the first end of the control module is connected to the external test power supply, the control module is used to receive the test voltage input by the external test power supply and output a shutdown signal; a switch module, the first end of the switch module is connected to the external test power supply, the second end of the switch module is connected to the second end of the control module, the third end of the switch module is connected to a matching resistor, and the switch module is used to receive the shutdown signal and stop transmitting the test voltage to the matching resistor. The present application realizes that when there is no short test, the input signal is output normally through the switch module, and when a short test is performed, the control module sends a shutdown signal to the switch module to turn off the switch module, so that the voltage of the short test cannot be loaded on the matching resistor, thereby protecting the matching resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of a short circuit protection circuit provided in one embodiment of the present application;

[0028] Figure 2 A schematic diagram of the structure of a control module in a short circuit protection circuit provided in an embodiment of the present application;

[0029] Figure 3 A detailed structural diagram of a control module in a short circuit protection circuit provided in an embodiment of the present application;

[0030] Figure 4 A detailed structural diagram of a control module in a short circuit protection circuit provided in another embodiment of the present application;

[0031] Figure 5 A schematic diagram of the structure of a switch module in a short circuit protection circuit provided in an embodiment of the present application;

[0032] Figure 6 A detailed structural diagram of a switch module in a short circuit protection circuit provided in an embodiment of the present application.

[0033] Description of Figure Numbers:

[0034]

[0035]

[0036] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0038] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0040] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In addition, in this application, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0042] CVBS signal is a composite synchronous video broadcast signal. The input impedance of the CVBS signal connector is generally 75 ohms, and the corresponding resistor package is generally 1206 / 0.25W at most. When the harness on the connector is short-circuited to the power supply (12V or 24V) and the ground for one minute, that is, when the power is applied to the CVBS signal line, the 75 ohm matching resistor is at risk of damage because the power exceeds the limit value. In traditional technology, it is protected by a dedicated socket, but the cost of the socket is high.

[0043] Based on this, the present application provides a short-circuit protection circuit, module, device and audio and video interface, wherein the short-circuit protection circuit includes: a control module and a switch module; the present application realizes that when there is no short-circuit test, the input signal is output normally through the switch module, and when the short-circuit test is performed, the control module sends a shutdown signal to the switch module to turn off the switch module, so that the voltage of the short-circuit test cannot be loaded onto the matching resistor, thereby protecting the matching resistor.

[0044] The present application provides a short protection circuit.

[0045] In one embodiment of the present application, refer to Figure 1 , Figure 1 A schematic diagram of the structure of a short circuit protection circuit provided in an embodiment of the present application, wherein the short circuit protection circuit is connected to an external power supply, the short circuit protection circuit is connected to an external test power supply, and the short circuit protection circuit includes:

[0046] A control module 10, wherein a first end of the control module 10 is connected to the external test power supply, and the control module 10 is used to receive a test voltage input by the external test power supply and output a shutdown signal;

[0047] A switch module 20, wherein a first end of the switch module 20 is connected to the external test power supply, a second end of the switch module 20 is connected to the control module 10, and a third end of the switch module 20 is connected to the matching resistor R0. The switch module 20 is used to receive the shutdown signal and stop transmitting the test voltage to the matching resistor.

[0048] In this embodiment, when an external test power supply inputs a test voltage to the signal input terminal CVBS_IN, that is, when a 12V or 24V test power supply is short-circuited to the signal input terminal CVBS_IN, the control module 10 detects that the test voltage of the signal input terminal CVBS_IN is greater than a preset voltage value, and sends a shutdown signal to the switch module 20. After receiving the shutdown signal, the switch module 20 stops transmitting the test voltage input by the test power supply to the matching resistor. As a result, the voltage of the short-circuit test cannot be loaded onto the matching resistor, thereby protecting the matching resistor.

[0049] It should be noted that the third end of the switch module 20 is also connected to the signal output terminal CVBS_OUT. When the signal input terminal CVBS_IN is not tested, the signal input terminal CVBS_IN is used to input audio and video signals. The voltage of the audio and video signals is 1V. The audio and video signals input by the signal input terminal CVBS_IN are transmitted to the signal output terminal CVBS_OUT through the switch module 20. The switch module 20 is in an open state under normal circumstances. Alternatively, when the signal input terminal CVBS_IN is used to input audio and video signals, the control module 10 sends an open signal to the switch module 20, thereby turning on the switch module 20.

[0050] In addition, the signal output terminal CVBS_OUT is connected to the video decoding chip to output the audio and video signal to the video decoding chip.

[0051] Optionally, in some feasible embodiments, reference Figure 2 , Figure 2 This is a schematic diagram of the structure of a control module in a short circuit protection circuit provided in an embodiment of the present application. The control module 10 includes:

[0052] A voltage dividing unit 11, a first end of the voltage dividing unit 11 is connected to a first end of the switch module 20;

[0053] A control unit 12 , wherein a first end of the control unit 12 is connected to a second end of the voltage dividing unit 11 , and a second end of the control unit 12 is connected to a second end of the switch module 20 .

[0054] In this embodiment, the voltage divider unit 11 is used to divide the voltage input by the signal input terminal CVBS_IN and transmit it to the control unit 12. When the signal input terminal CVBS_IN is not tested, the signal input terminal CVBS_IN is used to input the audio and video signal. The voltage divider unit 11 divides the voltage of the audio and video signal and transmits it to the control unit 12. The control unit 12 detects that the voltage of the audio and video signal after the voltage division is less than the preset voltage value. The control unit 12 sends an open signal to the switch module 20, thereby transmitting the audio and video signal input by the signal input terminal CVBS_IN to the signal output terminal CVBS_OUT. When performing a short circuit test, an external test power supply is connected to the signal input terminal CVBS_IN. After the control unit 12 receives the divided test voltage and compares it with the preset voltage value, if the control unit 12 detects that the divided test voltage is greater than the preset voltage value, it sends a shutdown signal to the switch module 20. After receiving the shutdown signal, the switch module 20 stops transmitting the test voltage input by the test power supply to the matching resistor, so that the voltage of the short circuit test cannot be loaded on the matching resistor, thereby protecting the matching resistor.

[0055] Optionally, in some feasible embodiments, reference Figure 3 , Figure 3 This is a detailed structural diagram of a control module in a short circuit protection circuit provided in an embodiment of the present application, wherein the voltage dividing unit 11 includes:

[0056] A first resistor R1, wherein a first end of the first resistor R1 is connected to the external test power supply, and a second end of the first resistor R1 is connected to a first end of the control unit 12;

[0057] A second resistor R2, wherein a first end of the second resistor R2 is connected to a first end of the control unit 12, and a second end of the second resistor R2 is grounded.

[0058] In this embodiment, the voltage input to the control unit 12 is adjusted by the first resistor R1 and the second resistor R2, so that the adjusted voltage matches the start-up condition of the control unit 12, and thus, the adjusted voltage satisfies the start-up condition of the control unit 12. Therefore, when the audio and video signal is input through the signal input terminal CVBS_IN, the voltage of the audio and video signal after voltage division by the first resistor R1 and the second resistor R2 is lower than the preset voltage value, and at this time, the input voltage does not reach the start-up voltage of the control unit 12, and the control unit 12 sends a start signal to the switch module 20, so that the audio and video signal input from the signal input terminal CVBS_IN is transmitted to the signal output terminal CVBS_OUT. When performing a short-circuit test, the external test power supply is connected to the signal input terminal CVBS_IN, and the input test voltage is adjusted through the first resistor R1 and the second resistor R2, and the divided test voltage is sent to the control unit 12. At this time, the divided test voltage reaches the start-up voltage of the control unit 12, so that the control unit 12 is turned on. After the control unit 12 is turned on, a shutdown signal is sent to the switch module 20, thereby stopping the test voltage input by the test power supply from being transmitted to the matching resistor, and then, the voltage of the short-circuit test cannot be loaded onto the matching resistor, thereby protecting the matching resistor.

[0059] Optionally, in some feasible embodiments, reference Figure 4 , Figure 4 This is a detailed structural diagram of a control module in a short circuit protection circuit provided in another embodiment of the present application, wherein the control unit 12 includes:

[0060] A transistor Q1, wherein a first end of the transistor Q1 is connected to a second end of the first resistor R1, a second end of the transistor Q1 is respectively connected to a preset reference voltage VCC and a second end of the switch module 20, and a third end of the transistor Q1 is grounded.

[0061] In this embodiment, when the audio and video signal is input through the signal input terminal CVBS_IN, the voltage of the audio and video signal after voltage division is lower than the preset voltage value, and the transistor Q1 is in the closed state at this time, so that the switch module 20 is turned on by the voltage of the preset reference voltage VCC, and the switch module 20 is turned on to transmit the audio and video signal input from the signal input terminal CVBS_IN to the signal output terminal CVBS_OUT. When performing a short circuit test, an external test power supply is connected to the signal input terminal CVBS_IN, and a 12V or 24V test power supply is input to the signal input terminal CVBS_IN. The test voltage after voltage division reaches the conduction condition of the transistor Q1, so that the transistor Q1 is turned on. After the transistor Q1 is turned on, a shutdown signal is sent to the switch module 20, thereby stopping the test voltage input from the test power supply from being transmitted to the matching resistor, and then, the voltage of the short circuit test cannot be loaded on the matching resistor, and then, the matching resistor is protected.

[0062] It should be noted that the preset reference voltage VCC is turned on based on the turning on of the transmission switch of the audio and video signal, or is provided by the power supply of the video decoding chip.

[0063] Optionally, in some feasible embodiments, reference Figure 4 , the control unit 12 further includes:

[0064] A third resistor R3 , a first end of the third resistor R3 is connected to the preset reference voltage VCC, and a second end of the third resistor R3 is connected to the second end of the transistor Q1 .

[0065] In this embodiment, the third resistor R3 acts as a current limiting resistor to provide a conduction condition for the transistor Q1. When the audio and video signal is input through the signal input terminal CVBS_IN, the voltage of the preset reference voltage VCC provides a conduction condition for the switch module 20, so that the switch module 20 is turned on. When the short-circuit test is performed, the external test power supply is connected to the signal input terminal CVBS_IN. At this time, the transistor Q1 is turned on, and the Vce voltage of the transistor Q1 is very small, so that the voltage at the second end of the third resistor R3 is almost 0, which is a shutdown signal sent to the switch module 20, thereby turning off the switch module 20 and stopping the test voltage input by the test power supply from being transmitted to the matching resistor. Then, the voltage of the short-circuit test cannot be loaded on the matching resistor, thereby protecting the matching resistor.

[0066] Optionally, in some feasible embodiments, reference Figure 5 , Figure 5 This is a schematic diagram of the structure of a switch module in a short circuit protection circuit provided in an embodiment of the present application. The switch module 20 includes:

[0067] Field effect transistor Q2, the first end of the field effect transistor Q2 is connected to the signal input end CVBS_IN, the second end of the field effect transistor Q2 is respectively connected to the first end of the matching resistor R0 and the signal output end CVBS_OUT, and the third end of the field effect transistor Q2 is connected to the second end of the transistor Q1.

[0068] In the present embodiment, when the audio and video signal is input through the signal input terminal CVBS_IN, the voltage of the preset reference voltage VCC provides a conduction condition for the field effect transistor Q2, so that the field effect transistor Q2 connects the external test power supply to the signal input terminal CVBS_IN when performing a short-circuit test. At this time, the transistor Q1 is turned on so that the voltage at the second end of the third resistor R3 is almost 0, which is a shutdown signal sent to the field effect transistor Q2, thereby turning off the switch module 20 and stopping the test voltage input by the test power supply from being transmitted to the matching resistor. As a result, the voltage of the short-circuit test cannot be loaded onto the matching resistor, thereby protecting the matching resistor.

[0069] Optionally, in some feasible embodiments, reference Figure 6 , Figure 6 This is a detailed structural diagram of a switch module in a short protection circuit provided in an embodiment of the present application, wherein the switch module 20 further includes:

[0070] Capacitor C1, a first end of the capacitor C1 is connected to the second end of the field effect transistor Q2, and a second end of the capacitor is used to output a signal.

[0071] In this embodiment, the second end of the capacitor C1 may be connected to the video decoding chip. The capacitor C1 plays a coupling role to prevent the DC voltage from being transmitted to the video decoding chip and only passes the AC voltage.

[0072] The present application also proposes a short-circuit protection module, which includes a short-circuit protection circuit. The specific structure of the short-circuit protection circuit refers to the above-mentioned embodiment. Since the optimized short-circuit protection module adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0073] The present application also proposes a short-circuit protection device, which includes a short-circuit protection module. The specific structure of the short-circuit protection circuit in the short-circuit protection module refers to the above-mentioned embodiment. Since the optimized short-circuit protection device adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0074] The present application also proposes an audio and video interface, which includes a short-circuit protection device. The specific structure of the short-circuit protection circuit in the short-circuit protection device refers to the above-mentioned embodiment. Since the present optimized audio and video interface adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0075] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the application concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A short circuit protection circuit, characterized in that: The short circuit protection circuit is connected to an external test power supply, and the short circuit protection circuit includes: A control module, a first end of which is connected to the external test power supply, and the control module is used to receive a test voltage input by the external test power supply and output a shutdown signal; A switch module, wherein the first end of the switch module is connected to the external test power supply, the second end of the switch module is connected to the second end of the control module, the third end of the switch module is connected to the matching resistor, and the switch module is used to receive the shutdown signal to stop transmitting the test voltage to the matching resistor.

2. The short protection circuit according to claim 1, characterized in that: The control module comprises: A voltage dividing unit, a first end of which is connected to a first end of the switch module; A control unit, wherein a first end of the control unit is connected to a second end of the voltage dividing unit, and a second end of the control unit is connected to a second end of the switch module.

3. The short protection circuit according to claim 2, characterized in that: The voltage dividing unit comprises: a first resistor, wherein a first end of the first resistor is connected to the external test power supply, and a second end of the first resistor is connected to a first end of the control unit; A second resistor, wherein a first end of the second resistor is connected to a first end of the control unit, and a second end of the second resistor is grounded.

4. The short protection circuit according to claim 3, characterized in that: The control unit comprises: A transistor, wherein the first end of the transistor is connected to the second end of the first resistor, the second end of the transistor is respectively connected to a preset reference voltage and the second end of the switch module, and the third end of the transistor is grounded.

5. The short protection circuit according to claim 4, characterized in that: The control unit also includes: A third resistor, wherein a first end of the third resistor is connected to the preset reference voltage, and a second end of the third resistor is connected to the second end of the transistor.

6. The short protection circuit according to claim 5, characterized in that: The switch module comprises: A field effect tube, wherein the first end of the field effect tube is connected to the signal input end, the second end of the field effect tube is respectively connected to the first end of the matching resistor and the signal output end, and the third end of the field effect tube is connected to the second end of the transistor.

7. The short protection circuit according to claim 6, characterized in that: The switch module also includes: A capacitor, wherein a first end of the capacitor is connected to a second end of the field effect tube, and a second end of the capacitor is used to output a signal.

8. A short circuit protection module, comprising the short circuit protection circuit according to any one of claims 1 to 7.

9. A short circuit protection device, characterized in that: The short circuit protection device comprises the short circuit protection module as claimed in claim 8.

10. An audio and video interface, characterized in that: The audio and video interface includes the short circuit protection device as claimed in claim 9.

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