Interface foreign matter detection circuit

Abstract

The utility model discloses an interface foreign matter detection circuit. The interface foreign matter detection circuit comprises a detection module and a judgment module, the detection module comprises a voltage dividing unit and a comparison unit, the voltage dividing unit is arranged between the SBU pin of the interface to be detected and the output end of the judgment module, and the comparison unit is arranged between the SBU pin of the interface to be detected and the input end of the judgment module. When a foreign matter appears at the interface to be detected, the interface generates impedance to the ground or VBUS, the comparison unit compares the generated impedance with the voltage dividing unit and then outputs a level signal, the judgment module analyzes the level signal and judges whether the foreign matter exists at the interface, the structure is simple, and the cost is low.

Description

Technical Field

[0001] The utility model relates to the technical field of interface detection, in particular to an interface foreign body detection circuit. Background Art

[0002] The charging ports of conventional electronic devices are often exposed, making them susceptible to foreign matter. Harsh operating environments, such as those where the charging port is frequently exposed to moisture or foreign matter, can lead to corrosion on the pins. This can cause the device to overheat, experience abnormal charging, or even burn out, posing a life-threatening hazard.

[0003] Some electronic devices on the market lack foreign object detection capabilities, requiring manual troubleshooting. Others require specialized chip design, but this approach places special demands on communication interfaces, increasing production costs.

[0004] The purpose of this application is to provide an interface foreign object detection circuit that solves at least one of the above problems. Utility Model Content

[0005] The purpose of the utility model is to provide an interface foreign body detection circuit designed to solve the deficiencies of the above-mentioned technology.

[0006] The utility model designs an interface foreign body detection circuit, which includes: a detection module and a judgment module;

[0007] The detection module includes a voltage dividing unit and a comparison unit, wherein the voltage dividing unit is arranged between the SBU pin of the interface to be detected and the output end of the judgment module, and the comparison unit is arranged between the SBU pin of the interface to be detected and the input end of the judgment module;

[0008] The voltage dividing unit is used to divide the voltage with the impedance generated when a foreign object appears at the interface to be detected;

[0009] The comparison unit is used to compare the generated impedance and the voltage divided by the voltage divider unit, and output a corresponding level signal;

[0010] The judging module is used to judge whether there is a foreign object on the interface to be detected according to the level signal;

[0011] The voltage dividing unit is a voltage dividing resistor, and the comparison unit is a field effect transistor.

[0012] Preferably, the detection module further comprises a protection unit, which is arranged between the SBU pin of the interface to be detected and a common connection point between the voltage divider unit and the comparison unit;

[0013] The protection unit is a protection resistor, the gate of the field effect tube is electrically connected to one end of the voltage divider resistor and one end of the protection resistor respectively, the source of the field effect tube is electrically connected to the ground end, the drain of the field effect tube is electrically connected to the input end of the judgment module, the other end of the protection resistor is electrically connected to the SBU pin, and the other end of the voltage divider resistor is electrically connected to the output end of the judgment module.

[0014] Preferably, the detection module further comprises a filter unit, one end of the filter unit is arranged between the common connection point of the protection unit and the voltage divider unit and the comparison unit, and the other end of the filter unit is electrically connected to the ground end;

[0015] The filtering unit is a filtering capacitor, which is arranged between the gate of the field effect tube and the ground terminal.

[0016] Preferably, the field effect transistor is an NMOS transistor.

[0017] Preferably, the interface to be detected is a USB charging interface.

[0018] The technical effect of the present invention is that when a foreign object appears at the interface to be detected, impedance will be generated at the interface to the ground or to VBUS. The comparison unit compares the generated impedance with the voltage divider unit and outputs a level signal. The judgment module analyzes the level signal to determine whether there is a foreign object with a small resistance at the interface. The structure is simple and the cost is low.

[0019] By designing the implementation circuit of the detection module, it can cover multiple detection signals such as foreign object short circuit to ground detection, foreign object short circuit to VBUS and no foreign object detection, thereby improving practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural principle block diagram of an interface foreign body detection circuit provided by the utility model;

[0021] Figure 2 yes Figure 1 The circuit schematic diagram in ;

[0022] Figure 3 yes Figure 1 There is no foreign matter or the foreign matter is short-circuited to the ground;

[0023] Figure 4 yes Figure 1 Schematic diagram of a foreign object shorting VBUS;

[0024] Figure 5 yes Figure 1 Comparison of waveforms at the output and input ends of the module when there is no foreign object, when the foreign object is short-circuited to ground, and when the foreign object is short-circuited to VBUS.

[0025] The reference numerals are as follows:

[0026] 1. Detection module, 2. Judgment module, 3. Voltage divider unit, 4. Comparison unit, 5. Interface to be detected, 6. Protection unit, 7. Filter unit. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0028] Example 1

[0029] In this embodiment, Figure 1 、 2 As shown, the present invention discloses an interface foreign object detection circuit, comprising: a detection module 1 and a judgment module 2; the detection module 1 includes a voltage divider unit 3 and a comparison unit 4, the voltage divider unit 3 being arranged between the SBU pin of the interface to be detected 5 and the output end of the judgment module 2, and the comparison unit 4 being arranged between the SBU pin of the interface to be detected 5 and the input end of the judgment module 2. The interface to be detected 5 is a USB charging interface.

[0030] The voltage divider unit 3 is used to divide the voltage with the impedance (i.e., foreign object resistance) generated when a foreign object appears at the interface to be detected 5; the comparison unit 4 is used to compare the generated impedance and the voltage divided by the voltage divider unit 3, and output a corresponding level signal; the judgment module 2 is used to judge whether there is a foreign object at the interface to be detected 5 based on the level signal.

[0031] The detection module 1 also includes a protection unit 6 and a filtering unit 7. The protection unit 6 is disposed between the SBU pin of the interface to be detected 5 and the common connection point between the voltage divider unit 3 and the comparison unit 4, and is used to limit current and protect the components in the detection circuit. One end of the filtering unit 7 is disposed between the common connection point of the protection unit 6 and the voltage divider unit 3 and the comparison unit 4, and the other end of the filtering unit 7 is electrically connected to the ground terminal to block direct current and pass alternating current, thereby improving the stability and reliability of the circuit.

[0032] like Figure 2As shown, the voltage dividing unit 3 is a voltage dividing resistor R1 (i.e., a matching resistor), the protection unit 6 is a protection resistor R2, the filtering unit 7 is a filtering capacitor C1, and the comparison unit 4 is a field effect transistor Q1 (i.e., a MOS transistor); the gate of the field effect transistor Q1 is electrically connected to one end of the voltage dividing resistor R1 and one end of the protection resistor R2 respectively, the source of the field effect transistor Q1 is electrically connected to the ground terminal, the drain of the field effect transistor Q1 is electrically connected to the input terminal of the judgment module 2, the other end of the protection resistor R2 is electrically connected to the SBU pin, and the other end of the voltage dividing resistor R1 is electrically connected to the output terminal of the judgment module 2. In this embodiment, the field effect transistor is an NMOS transistor.

[0033] When the interface 5 to be detected is in normal use, the turn-on voltage of the MOS transistor is Vgh. When the voltage flowing through the gate of the MOS transistor > Vgh, the MOS transistor conducts, and the comparison unit 4 outputs a logic of low level. When the voltage flowing through the gate of the MOS transistor < Vgh, the MOS transistor turns off, and the comparison unit 4 outputs a logic of high level.

[0034] The input terminal of the judgment module 2 (i.e., CPU-IN) is used for configuration input, and there is a 1.8V pull-up inside it, which is used to judge whether the logic is high level or low level.

[0035] The output terminal of the judgment module 2 (i.e., CPU-OUT) is used for configuration output, and there are two cases of output logic high or logic low. When the logic of CPU-OUT is high level (i.e., 1), the output voltage of the judgment module 2 is 1.8V. When the logic of CPU-OUT is low level (i.e., 0), the output voltage of the judgment module 2 is 0V.

[0036] The working principle of the interface foreign object detection circuit disclosed by the present utility model is as follows:

[0037] As Figure 3 、 5 shown, when there is no foreign object at the interface 5 to be detected, the logic of CPU-OUT is high level, and its output voltage is 1.8V. Since there is no foreign object, it can be considered that the foreign object resistance is infinite at this time. The voltage flowing through the gate of the MOS transistor is greater than Vgh, the MOS transistor conducts, and the output logic is low level; when the logic of CPU-OUT is low level, its output voltage is 0V. At this time, it can be considered that the foreign object resistance is infinite, the voltage flowing through the gate of the MOS transistor is less than Vgh, the MOS transistor cannot conduct normally, and the output logic is high level.

[0038] When there is a foreign object at the detection interface 5 and the foreign object resistance is small, the CPU-OUT logic is high, its output voltage is 1.8V, the foreign object resistance is small, the voltage flowing through the MOS transistor gate is less than Vgh, the MOS transistor cannot conduct normally, and the output logic is high. When the CPU-OUT logic is low, its output voltage is 0V, the voltage flowing through the MOS transistor gate is 0V, the MOS transistor cannot conduct normally, and the output logic is high. Judgment module 2 determines that the foreign object is short-circuited to ground.

[0039] like Figure 4 、 5 As shown, when there is a foreign object at the interface to be detected 5 and the foreign object resistance is small, the CPU-OUT logic is high, its output voltage is 1.8V, the voltage flowing through the MOS transistor gate is greater than Vgh, the MOS transistor is normally turned on, and the output logic is low. When the CPU-OUT logic is low, its output voltage is 0V, the foreign object resistance is small, the voltage flowing through the MOS transistor gate is greater than Vgh, the MOS transistor is normally turned on, and the output logic is low. Judgment module 2 determines that the foreign object has shorted VBUS.

[0040] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. An interface foreign body detection circuit, characterized in that: include: Detection module (1) and judgment module (2); The detection module (1) comprises a voltage dividing unit (3) and a comparison unit (4); the voltage dividing unit (3) is arranged between the SBU pin of the interface to be detected (5) and the output end of the judgment module (2); and the comparison unit (4) is arranged between the SBU pin of the interface to be detected (5) and the input end of the judgment module (2); The voltage dividing unit (3) is used to divide the voltage with the impedance generated when a foreign object appears on the interface to be detected (5); The comparison unit (4) is used to compare the generated impedance and the voltage divided by the voltage dividing unit (3), and output a corresponding level signal; The judgment module (2) is used to judge whether there is a foreign object on the interface to be detected (5) based on the level signal; The voltage dividing unit (3) is a voltage dividing resistor, and the comparison unit (4) is a field effect tube.

2. The interface foreign body detection circuit according to claim 1, wherein: The detection module (1) further comprises a protection unit (6), wherein the protection unit (6) is arranged between the SBU pin of the interface to be detected (5) and a common connection point between the voltage dividing unit (3) and the comparison unit (4); The protection unit (6) is a protection resistor, the gate of the field effect tube is electrically connected to one end of the voltage divider resistor and one end of the protection resistor respectively, the source of the field effect tube is electrically connected to the ground end, the drain of the field effect tube is electrically connected to the input end of the judgment module (2), the other end of the protection resistor is electrically connected to the SBU pin, and the other end of the voltage divider resistor is electrically connected to the output end of the judgment module (2).

3. The interface foreign body detection circuit according to claim 2, wherein: The detection module (1) further comprises a filter unit (7), one end of the filter unit (7) being arranged between the common connection point of the protection unit (6), the voltage divider unit (3) and the comparison unit (4), and the other end of the filter unit (7) being electrically connected to the ground end; The filtering unit (7) is a filtering capacitor, and the filtering capacitor is arranged between the gate of the field effect tube and the ground terminal.

4. The interface foreign body detection circuit according to claim 1, wherein: The field effect tube is an NMOS tube.

5. The interface foreign body detection circuit according to any one of claims 1 to 4, characterized in that: The interface to be detected (5) is a USB charging interface.

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