CN110120662B

CN110120662B - Line protection circuit

Info

Publication number: CN110120662B
Application number: CN201910349619.6A
Authority: CN
Inventors: 范建功; 吕浙波
Original assignee: Nubia Technology Co Ltd
Current assignee: Nubia Technology Co Ltd
Priority date: 2019-04-28
Filing date: 2019-04-28
Publication date: 2022-05-24
Anticipated expiration: 2039-04-28
Also published as: CN110120662A

Abstract

The invention discloses a line protection circuit, which is used in an intelligent mobile terminal, wherein the intelligent mobile terminal comprises: the circuit protection circuit comprises an interface circuit and a central processing unit, wherein the interface circuit is connected with the central processing unit through a data transmission line, and the circuit protection circuit at least comprises: the first-stage protection circuit and the second-stage protection circuit are used for protecting abnormal voltage or current, the first-stage protection circuit and the second-stage protection circuit are sequentially connected to the interface circuit to the central processing unit on the data transmission line, and the first-stage protection circuit and the second-stage protection circuit are different in type. By applying the embodiment of the invention, the problem of insufficient protection capability of abnormal current or voltage in the conventional mobile terminal can be solved.

Description

Line protection circuit

Technical Field

The invention relates to the field of electronic circuits, in particular to a line protection circuit for an intelligent mobile terminal.

Background

The IC (Integrated Circuit) industry has been developed vigorously, so that the IC chip has higher and higher integration level. But limited by the limitation of chip area, the width and length of MOS (Metal Oxide Semiconductor) transistors in the IC chip become smaller and the number of MOS transistors becomes larger. In such a case, the capability of the IC chip to resist external abnormal current or voltage (mainly, large current or high voltage) impact (such as ESD (Electro-Static discharge), surge, etc.) will be reduced. Once the chip is impacted and damaged, the chip is irreparably damaged by the user; for example, after a CPU (Central Processing Unit) is damaged due to an abnormal current or voltage, the only method is to replace the CPU.

Such abnormal current or voltage problems, which are particularly common in smart phones, arise from: in the use of smart phone, the user often inserts the charger and charges for smart phone, often inserts the earphone in order to adopt the earphone to listen to the music, often inserts the data line in order to carry out data transmission, and these conventional operations inevitably bring brief heavy current or voltage, all have the risk of damaging the chip.

Observing the existing circuit design of the smart phone, in terms of protecting critical components (such as a CPU) from a large current and/or a high Voltage, a single TVS (Transient Voltage suppressor) is generally used for protection. However, the protection structure of a single TVS tube is difficult to adapt to a large current or high voltage scene with a wide variety of scenes in a smart phone, so that the prior art needs to be improved.

Disclosure of Invention

The invention mainly aims to provide a line protection circuit which is used in an intelligent mobile terminal and used for solving the problem that the existing abnormal current or voltage protection capability is insufficient.

In order to achieve the above object, the present invention provides a line protection circuit for use in an intelligent mobile terminal, the intelligent mobile terminal including: the circuit protection circuit comprises an interface circuit and a central processing unit, wherein the interface circuit is connected with the central processing unit through a data transmission line, and the circuit protection circuit at least comprises: the first-stage protection circuit and the second-stage protection circuit are used for protecting abnormal voltage or current, the first-stage protection circuit and the second-stage protection circuit are sequentially connected to the data transmission line from the interface circuit to the central processing unit, and the first-stage protection circuit and the second-stage protection circuit are different in type.

Wherein the first stage protection circuit comprises: a transient voltage suppression diode, the second stage protection circuit comprising: an overvoltage protection circuit.

The interface circuit, the first-stage protection circuit and the second-stage protection circuit are arranged on a first circuit board, and the central processing unit is arranged on a second circuit board which is different from and separated from the first circuit board.

Wherein the line protection circuit further comprises: and the third-stage protection circuit is connected to the data transmission line between the second-stage protection circuit and the central processing unit.

Wherein the third stage protection circuit comprises: a transient voltage suppression diode.

Wherein the line protection circuit further comprises: and the magnetic beads are connected to the data transmission line between the third-stage protection circuit and the central processing unit.

The first-stage protection circuit and the second-stage protection circuit are arranged on a first circuit board, and the central processing unit and the third-stage protection circuit are arranged on a second circuit board which is different from and separated from the first circuit board.

The data transmission line is a single data transmission line or a double data transmission line for transmitting differential signals.

Wherein the interface circuit is a USB interface, and the USB interface includes: VBUS pin, D + pin, D-pin, the data transmission line includes: the D + pin and the D-pin are respectively connected to the central processor through the first data transmission line and the second data transmission line; wherein the first switching transistor is connected in series on the second data transmission line; wherein the second switching transistor is connected in series with V of the CPU_USBThe pin and the D-pin; wherein the third switching transistor is connected in series with the V_USBBetween the pin and the power management chip; the control end of the first switch transistor, the control end of the second switch transistor and the control end of the third switch transistor are all connected with the VBUS pin.

Wherein the interface circuit is a USB interface, and the USB interface includes: VBUS pin, D + pin, D-pin, the data transmission line includes: the D + pin and the D-pin are respectively connected to the central processor through the first data transmission line and the second data transmission line; the first stage protection circuit comprises transient voltage suppression diodes T1, T2;

wherein the transient voltage suppression diode T1 is connected to the D + pin and ground; the first switching transistor is connected in series with the second data transmission line; the transient voltage suppression diode T1 is connected with the D pin and the ground;

the second switching transistor is connected between a VUSB pin of the CPU and the D-pin in series;

the third switching transistor is connected between a VUSB pin of the CPU and the power management chip in series;

the control end of the first switch transistor, the control end of the second switch transistor and the control end of the third switch transistor are all connected with the VBUS pin.

When the interface circuit cannot work normally, the first switching transistor and the third switching transistor are turned off and the second switching transistor is turned on to detect the impedance to ground of the D-pin of the USB interface so as to determine whether the central processing unit is abnormal and the power management chip is abnormal.

The line protection circuit provided by the invention is used in an intelligent mobile terminal, and adopts a multi-stage protection circuit (such as a first-stage protection circuit and a second-stage protection circuit) to protect abnormal voltage or current so as to solve the problem of insufficient protection capability of the conventional abnormal current or voltage.

In addition, the embodiment of the invention also refers to a switch transistor to quickly locate the fault of the CPU or the power management chip.

Drawings

Fig. 1 is a schematic diagram of a hardware structure of a mobile terminal implementing various embodiments of the present invention;

FIG. 2 is a diagram of a wireless communication system for the mobile terminal shown in FIG. 1;

fig. 3 is a block diagram of a first embodiment of a line protection circuit according to the present invention;

fig. 4 is a block diagram of a second embodiment of the line protection circuit according to the present invention;

fig. 5 is a block diagram of a second embodiment of the line protection circuit according to the present invention;

fig. 6 is a block diagram of a second embodiment of the line protection circuit according to the present invention;

fig. 7 is a block diagram of a third embodiment of the line protection circuit according to the present invention;

fig. 8 is a circuit diagram of a fourth embodiment of the line protection circuit according to the present invention;

the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

A mobile terminal implementing various embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for facilitating the explanation of the present invention, and have no specific meaning in themselves. Thus, "module" and "component" may be used in a mixture.

The mobile terminal may be implemented in various forms. For example, the terminal described in the present invention may include a mobile terminal such as a mobile phone, a smart phone, a notebook computer, a digital broadcast receiver, a PDA (personal digital assistant), a PAD (tablet computer), a PMP (portable multimedia player), a navigation device, and the like, and a stationary terminal such as a digital TV, a desktop computer, and the like. In the following, it is assumed that the terminal is a mobile terminal. However, it will be understood by those skilled in the art that the configuration according to the embodiment of the present invention can be applied to a fixed type terminal in addition to elements particularly used for moving purposes.

Fig. 1 is a schematic hardware structure of a mobile terminal implementing various embodiments of the present invention.

The mobile terminal 100 may include a wireless communication unit 110, an a/V (audio/video) input unit 120, a user input unit 130, a sensing unit 140, an output unit 150, a memory 160, an interface unit 170, a controller 180, and a power supply unit 190, etc. Fig. 1 illustrates a mobile terminal having various components, but it is to be understood that not all illustrated components are required to be implemented. More or fewer components may alternatively be implemented. Elements of the mobile terminal will be described in detail below.

The wireless communication unit 110 typically includes one or more components that allow radio communication between the mobile terminal 100 and a wireless communication system or network. For example, the wireless communication unit may include at least one of a broadcast receiving module 111, a mobile communication module 112, a wireless internet module 113, a short-range communication module 114, and a location information module 115.

The broadcast receiving module 111 receives a broadcast signal and/or broadcast associated information from an external broadcast management server via a broadcast channel. The broadcast channel may include a satellite channel and/or a terrestrial channel. The broadcast management server may be a server that generates and transmits a broadcast signal and/or broadcast associated information or a server that receives a previously generated broadcast signal and/or broadcast associated information and transmits it to a terminal. The broadcast signal may include a TV broadcast signal, a radio broadcast signal, a data broadcast signal, and the like. Also, the broadcast signal may further include a broadcast signal combined with a TV or radio broadcast signal. The broadcast associated information may also be provided via a mobile communication network, and in this case, the broadcast associated information may be received by the mobile communication module 112. The broadcast signal may exist in various forms, for example, it may exist in the form of an Electronic Program Guide (EPG) of Digital Multimedia Broadcasting (DMB), an Electronic Service Guide (ESG) of digital video broadcasting-handheld (DVB-H), and the like. The broadcast receiving module 111 may receive a signal broadcast by using various types of broadcasting systems. In particular, the broadcast receiving module 111 may receive a broadcast signal by using a signal such as multimedia broadcasting-terrestrial (DMB-T), digital multimedia broadcasting-satellite (DMB-S), digital video broadcasting-handheld (DVB-H), forward link media (MediaFLO)^@) A digital broadcasting system of a terrestrial digital broadcasting integrated service (ISDB-T), etc. receives digital broadcasting. The broadcast receiving module 111 may be constructed to be suitable for various broadcasting systems that provide broadcast signals as well as the above-mentioned digital broadcasting systems. The broadcast signal and/or broadcast associated information received via the broadcast receiving module 111 may be stored in the memory 160 (or other type of storage medium).

The mobile communication module 112 transmits and/or receives radio signals to and/or from at least one of a base station (e.g., access point, node B, etc.), an external terminal, and a server. Such radio signals may include voice call signals, video call signals, or various types of data transmitted and/or received according to text and/or multimedia messages.

The wireless internet module 113 supports wireless internet access of the mobile terminal. The module may be internally or externally coupled to the terminal. The wireless internet access technology to which the module relates may include WLAN (wireless LAN) (Wi-Fi), Wibro (wireless broadband), Wimax (worldwide interoperability for microwave access), HSDPA (high speed downlink packet access), and the like.

The short-range communication module 114 is a module for supporting short-range communication. Some examples of short-range communication technologies include bluetooth^TMRadio Frequency Identification (RFID), infrared data association (IrDA), Ultra Wideband (UWB), zigbee^TMAnd so on.

The location information module 115 is a module for checking or acquiring location information of the mobile terminal. A typical example of the location information module is a GPS (global positioning system). According to the current technology, the GPS module 115 calculates distance information and accurate time information from three or more satellites and applies triangulation to the calculated information, thereby accurately calculating three-dimensional current location information according to longitude, latitude, and altitude. Currently, a method for calculating position and time information uses three satellites and corrects an error of the calculated position and time information by using another satellite. In addition, the GPS module 115 can calculate speed information by continuously calculating current position information in real time.

The a/V input unit 120 is used to receive an audio or video signal. The a/V input unit 120 may include a camera 121 and a microphone 1220, and the camera 121 processes image data of still pictures or video obtained by an image capturing apparatus in a video capturing mode or an image capturing mode. The processed image frames may be displayed on the display unit 151. The image frames processed by the camera 121 may be stored in the memory 160 (or other storage medium) or transmitted via the wireless communication unit 110, and two or more cameras 1210 may be provided according to the construction of the mobile terminal. The microphone 122 may receive sounds (audio data) via the microphone in a phone call mode, a recording mode, a voice recognition mode, or the like, and can process such sounds into audio data. The processed audio (voice) data may be converted into a format output transmittable to a mobile communication base station via the mobile communication module 112 in case of a phone call mode. The microphone 122 may implement various types of noise cancellation (or suppression) algorithms to cancel (or suppress) noise or interference generated in the course of receiving and transmitting audio signals.

The user input unit 130 may generate key input data according to a command input by a user to control various operations of the mobile terminal. The user input unit 130 allows a user to input various types of information, and may include a keyboard, dome sheet, touch pad (e.g., a touch-sensitive member that detects changes in resistance, pressure, capacitance, and the like due to being touched), scroll wheel, joystick, and the like. In particular, when the touch pad is superimposed on the display unit 151 in the form of a layer, a touch screen may be formed.

The sensing unit 140 detects a current state of the mobile terminal 100 (e.g., an open or closed state of the mobile terminal 100), a position of the mobile terminal 100, presence or absence of contact (i.e., touch input) by a user with the mobile terminal 100, an orientation of the mobile terminal 100, acceleration or deceleration movement and direction of the mobile terminal 100, and the like, and generates a command or signal for controlling an operation of the mobile terminal 100. For example, when the mobile terminal 100 is implemented as a slide-type mobile phone, the sensing unit 140 may sense whether the slide-type phone is opened or closed. In addition, the sensing unit 140 can detect whether the power supply unit 190 supplies power or whether the interface unit 170 is coupled with an external device. The sensing unit 140 may include a proximity sensor 1410 as will be described below in connection with a touch screen.

The interface unit 170 serves as an interface through which at least one external device is connected to the mobile terminal 100. For example, the external device may include a wired or wireless headset port, an external power supply (or battery charger) port, a wired or wireless data port, a memory card port, a port for connecting a device having an identification module, an audio input/output (I/O) port, a video I/O port, an earphone port, and the like. The identification module may store various information for authenticating a user using the mobile terminal 100 and may include a User Identity Module (UIM), a Subscriber Identity Module (SIM), a Universal Subscriber Identity Module (USIM), and the like. In addition, a device having an identification module (hereinafter, referred to as an "identification device") may take the form of a smart card, and thus, the identification device may be connected with the mobile terminal 100 via a port or other connection means. The interface unit 170 may be used to receive input (e.g., data information, power, etc.) from an external device and transmit the received input to one or more elements within the mobile terminal 100 or may be used to transmit data between the mobile terminal and the external device.

In addition, when the mobile terminal 100 is connected with an external cradle, the interface unit 170 may serve as a path through which power is supplied from the cradle to the mobile terminal 100 or may serve as a path through which various command signals input from the cradle are transmitted to the mobile terminal. Various command signals or power input from the cradle may be used as signals for recognizing whether the mobile terminal is accurately mounted on the cradle. The output unit 150 is configured to provide output signals (e.g., audio signals, video signals, alarm signals, vibration signals, etc.) in a visual, audio, and/or tactile manner. The output unit 150 may include a display unit 151, an audio output module 152, an alarm unit 153, and the like.

The display unit 151 may display information processed in the mobile terminal 100. For example, when the mobile terminal 100 is in a phone call mode, the display unit 151 may display a User Interface (UI) or a Graphical User Interface (GUI) related to a call or other communication (e.g., text messaging, multimedia file downloading, etc.). When the mobile terminal 100 is in a video call mode or an image capturing mode, the display unit 151 may display a captured image and/or a received image, a UI or GUI showing a video or an image and related functions, and the like.

Meanwhile, when the display unit 151 and the touch pad are stacked on each other in the form of a layer to form a touch screen, the display unit 151 may serve as an input device and an output device. The display unit 151 may include at least one of a Liquid Crystal Display (LCD), a thin film transistor LCD (TFT-LCD), an Organic Light Emitting Diode (OLED) display, a flexible display, a three-dimensional (3D) display, and the like. Some of these displays may be configured to be transparent to allow a user to see from the outside, which may be referred to as transparent displays, and a typical transparent display may be, for example, a TOLED (transparent organic light emitting diode) display or the like. Depending on the particular desired implementation, the mobile terminal 100 may include two or more display units (or other display devices), for example, the mobile terminal may include an external display unit (not shown) and an internal display unit (not shown). The touch screen may be used to detect a touch input pressure as well as a touch input position and a touch input area.

The audio output module 152 may convert audio data received by the wireless communication unit 110 or stored in the memory 160 into an audio signal and output as sound when the mobile terminal is in a call signal reception mode, a call mode, a recording mode, a voice recognition mode, a broadcast reception mode, or the like. Also, the audio output module 152 may provide audio output related to a specific function performed by the mobile terminal 100 (e.g., a call signal reception sound, a message reception sound, etc.). The audio output module 152 may include a speaker, a buzzer, and the like.

The alarm unit 153 may provide an output to notify the mobile terminal 100 of the occurrence of an event. Typical events may include call reception, message reception, key signal input, touch input, and the like. In addition to audio or video output, the alarm unit 153 may provide output in different ways to notify the occurrence of an event. For example, the alarm unit 153 may provide an output in the form of vibration, and when a call, a message, or some other incoming communication (incomingmunication) is received, the alarm unit 153 may provide a tactile output (i.e., vibration) to inform the user thereof. By providing such a tactile output, the user can recognize the occurrence of various events even when the user's mobile phone is in the user's pocket. The alarm unit 153 may also provide an output notifying the occurrence of an event via the display unit 151 or the audio output module 152.

The memory 160 may store software programs and the like for processing and controlling operations performed by the controller 180, or may temporarily store data (e.g., a phonebook, messages, still images, videos, and the like) that has been or will be output. Also, the memory 160 may store data regarding various ways of vibration and audio signals output when a touch is applied to the touch screen.

The memory 160 may include at least one type of storage medium including a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory, etc.), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, an optical disk, and the like. Also, the mobile terminal 100 may cooperate with a network storage device that performs a storage function of the memory 160 through a network connection.

The controller 180 generally controls the overall operation of the mobile terminal. For example, the controller 180 performs control and processing related to voice calls, data communications, video calls, and the like. In addition, the controller 180 may include a multimedia module 1810 for reproducing (or playing back) multimedia data, and the multimedia module 1810 may be constructed within the controller 180 or may be constructed separately from the controller 180. The controller 180 may perform a pattern recognition process to recognize a handwriting input or a picture drawing input performed on the touch screen as a character or an image.

The power supply unit 190 receives external power or internal power and provides appropriate power required to operate various elements and components under the control of the controller 180.

The various embodiments described herein may be implemented in a computer-readable medium using, for example, computer software, hardware, or any combination thereof. For a hardware implementation, the embodiments described herein may be implemented using at least one of an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), a processor, a controller, a microcontroller, a microprocessor, an electronic unit designed to perform the functions described herein, and in some cases, such embodiments may be implemented in the controller 180. For a software implementation, the implementation such as a process or a function may be implemented with a separate software module that allows performing at least one function or operation. The software codes may be implemented by software applications (or programs) written in any suitable programming language, which may be stored in the memory 160 and executed by the controller 180.

Up to this point, mobile terminals have been described in terms of their functionality. Hereinafter, a slide-type mobile terminal among various types of mobile terminals, such as a folder-type, bar-type, swing-type, slide-type mobile terminal, and the like, will be described as an example for the sake of brevity. Accordingly, the present invention can be applied to any type of mobile terminal, and is not limited to a slide type mobile terminal.

The mobile terminal 100 as shown in fig. 1 may be configured to operate with communication systems such as wired and wireless communication systems and satellite-based communication systems that transmit data via frames or packets.

A communication system in which a mobile terminal according to the present invention is operable will now be described with reference to fig. 2.

Such communication systems may use different air interfaces and/or physical layers. For example, the air interface used by the communication system includes, for example, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), and Universal Mobile Telecommunications System (UMTS) (in particular, Long Term Evolution (LTE)), global system for mobile communications (GSM), and the like. By way of non-limiting example, the following description relates to a CDMA communication system, but such teachings are equally applicable to other types of systems.

Referring to fig. 2, the CDMA wireless communication system may include a plurality of mobile terminals 100, a plurality of Base Stations (BSs) 270, Base Station Controllers (BSCs) 275, and a Mobile Switching Center (MSC) 280. The MSC280 is configured to interface with a Public Switched Telephone Network (PSTN) 290. The MSC280 is also configured to interface with a BSC275, which may be coupled to the base station 270 via a backhaul. The backhaul may be constructed according to any of several known interfaces including, for example, E1/T1, ATM, IP, PPP, frame Relay, HDSL, ADSL, or xDSL. It will be understood that a system as shown in fig. 2 may include multiple BSCs 2750.

Each BS270 may serve one or more sectors (or regions), each sector covered by a multi-directional antenna or an antenna pointing in a particular direction being radially distant from the BS 270. Alternatively, each partition may be covered by two or more antennas for diversity reception. Each BS270 may be configured to support multiple frequency allocations, with each frequency allocation having a particular frequency spectrum (e.g., 1.25MHz,5MHz, etc.).

The intersection of partitions with frequency allocations may be referred to as a CDMA channel. The BS270 may also be referred to as a Base Transceiver Subsystem (BTS) or other equivalent terminology. In such a case, the term "base station" may be used to generically refer to a single BSC275 and at least one BS 270. Base stations may also be referred to as "cells". Alternatively, each sector of a particular BS270 may be referred to as a plurality of cell sites.

As shown in fig. 2, a Broadcast Transmitter (BT)295 transmits a broadcast signal to the mobile terminal 100 operating within the system. A broadcast receiving module 111 as shown in fig. 1 is provided at the mobile terminal 100 to receive a broadcast signal transmitted by the BT 295. In fig. 2, several Global Positioning System (GPS) satellites 300 are shown. The satellite 300 assists in locating at least one of the plurality of mobile terminals 100.

In fig. 2, a plurality of satellites 300 are depicted, but it is understood that useful positioning information may be obtained with any number of satellites. The GPS module 115 as shown in fig. 1 is generally configured to cooperate with satellites 300 to obtain desired positioning information. Other techniques that can track the location of the mobile terminal may be used instead of or in addition to GPS tracking techniques. In addition, at least one GPS satellite 300 may selectively or additionally process satellite DMB transmission.

As a typical operation of the wireless communication system, the BS270 receives reverse link signals from various mobile terminals 100. The mobile terminal 100 is generally engaged in conversations, messaging, and other types of communications. Each reverse link signal received by a particular base station 270 is processed within the particular BS 270. The obtained data is forwarded to the associated BSC 275. The BSC provides call resource allocation and mobility management functions including coordination of soft handoff procedures between BSs 270. The BSCs 275 also route the received data to the MSC280, which provides additional routing services for interfacing with the PSTN 290. Similarly, the PSTN290 interfaces with the MSC280, the MSC interfaces with the BSCs 275, and the BSCs 275 accordingly control the BS270 to transmit forward link signals to the mobile terminal 100.

Based on the above-mentioned mobile terminal hardware structure and communication system, various embodiments of a line protection circuit of the present invention are proposed.

As shown in fig. 3, a line protection circuit according to a first embodiment of the present invention may be used in the above-mentioned smart mobile terminal. This intelligent mobile terminal includes: the interface circuit 101 is connected to a central processing unit 102, i.e., a CPU 102, wherein the interface circuit 101 is connected to the central processing unit 102 via a data transmission line. The line protection circuit includes at least: the protection circuit comprises a first-stage protection circuit 103 and a second-stage protection circuit 104 for protecting abnormal voltage or current, wherein the first-stage protection circuit 103 and the second-stage protection circuit 104 are sequentially connected to a data transmission line from an interface circuit 101 to a central processing unit 102, and the types of the first-stage protection circuit 103 and the second-stage protection circuit 104 are different.

The interface circuit 101, the first protection circuit 103, and the second protection circuit 104 are disposed on a first circuit board, such as a radio frequency board of the smart mobile terminal. Specifically, the first stage protection circuit 103 specifically includes a transient voltage suppression diode, i.e., TVS transistor, and the second stage protection circuit 104 specifically includes an overvoltage protection circuit, such as an overvoltage protection device OVP. The interface circuit 101 may be a USB interface circuit.

When abnormal voltage is input from the outside, taking static as an example, the static will enter the intelligent mobile terminal through the interface circuit 101, and the TVS of the first-stage protection circuit 103 will clamp the static to rapidly reduce the static voltage, usually the clamping voltage is above 16V; when clamping voltage is input into the OVP, overvoltage protection operation is carried out, different CPUs have different requirements on input voltage, the protection voltage for the OVP is different, and when the OVP is triggered, the output voltage is limited so as to protect subsequent loads.

According to the line protection circuit provided by the embodiment of the invention, as a user operates more interface circuits of the intelligent mobile terminal, the first-stage protection circuit and the second-stage protection circuit are arranged between the interface circuit of the intelligent mobile terminal and the central processing unit so as to protect the abnormal voltage or current flowing into the external circuit, and the problem of insufficient protection capability of the conventional abnormal current or voltage is better solved.

Fig. 4 to 6 show a line protection circuit according to a second embodiment of the present invention. Different from the previous embodiment, the line protection circuit according to the embodiment of the present invention further includes: third stage guard circuit 105. The third-stage protection circuit 105 is connected to the data transmission line between the second-stage protection circuit 104 and the central processor 102. The third stage protection circuit 105 may be a transient voltage suppression diode, i.e. TVS transistor. The line protection circuit may further include: and a magnetic bead 106 connected to the data transmission line between the third-stage protection circuit 105 and the central processor 102.

The first-stage protection circuit 103 and the second-stage protection circuit 104 are disposed on the first circuit board, specifically disposed on the radio frequency platelet of the intelligent terminal. And the cpu 102 and the third-stage protection circuit 105 are disposed on a second circuit board different and separate from the first circuit board, such as a motherboard of the intelligent terminal. The data transmission line is a single data transmission line or a double data transmission line for transmitting differential signals. The magnetic beads 106 are arranged to filter out electromagnetic interference under high-speed transmission data.

When the line protection circuit works, when abnormal voltage is input from the outside, taking static as an example, the static can enter the mobile terminal through the interface circuit 101, the first-stage protection circuit 101TVS tube clamps the static to rapidly reduce the static voltage, and the clamping voltage is usually more than 16V; when clamping voltage is input into the OVP, overvoltage protection operation is carried out, different CPUs have different requirements on input voltage and have different protection voltage on the OVP, and when the OVP is triggered, output voltage is limited so as to protect subsequent loads; the third pole protection circuit 105TVS at the side of the main board is used to protect the abnormal introduction (such as electrostatic introduction) at the side of the main board, and when an abnormal voltage is input, the voltage can be rapidly reduced to realize protection.

According to the circuit protection circuit provided by the embodiment of the invention, abnormal voltage or current flowing into the external is protected by adopting the multi-stage protection circuit (such as the first-stage protection circuit, the second-stage protection circuit and the third-stage protection circuit), so that the problem of insufficient protection capability of the conventional abnormal current or voltage is solved, and the repair rate of the intelligent mobile terminal is reduced.

As shown in fig. 7, it is a line protection circuit provided by a third embodiment of the present invention, wherein the interface circuit 101 is specifically a USB interface, and the USB interface includes: VBUS pin, D + pin, D-pin. Wherein, the data transmission line includes: a first data transmission line and a second data transmission line. The D + pin and the D-pin of the USB interface are respectively connected to the central processor 102 through a first data transmission line and a second data transmission line;

wherein, the first switching transistor 203 is connected in series on the second data transmission line; the second switching transistor 205 is connected in series with V of the CPU 102_USBBetween the pin and the D-pin; the third switching transistor 204 is connected in series with V of the CPU 102_USBPins and the power management chip 201. The control terminal of the first switching transistor 203, the control terminal of the second switching transistor 205, and the control terminal of the third switching transistor 204 are all connected to the VBUS pin of the USB interface.

When the line protection circuit of the embodiment of the present invention works, if the USB interface line is damaged (for example, the USB interface line cannot be charged and cannot be connected to a computer), a control signal is input to the VBUS side of the USB data line end to turn off the first switching transistor 203 and the third switching transistor 204 and turn on the second switching transistor 205, so as to detect the impedance to ground of the D-pin of the USB interface to determine whether the cpu is abnormal and whether the power management chip is abnormal. If the impedance is low, the CPU is abnormal, if the impedance is normal, the PM of the power management chip is abnormal, and only the targeted device needs to be replaced according to the result, so that the maintenance efficiency is improved.

As shown in fig. 8, it is a line protection circuit according to a fourth embodiment of the present invention, wherein the interface circuit 101 is specifically in a USB interface form, for example, a Type-C interface. The USB interface includes: VBUS pin, D + pin, D-pin and GND pin. The first stage protection circuit 103 includes transient voltage suppression diodes T1, T2; the second stage protection circuit 104 is embodied as an overvoltage protection device OVP, and the third stage protection circuit 103 includes transient voltage suppression diodes T3, T4. The first switch transistor 203 is an NMOS transistor N2, the second switch transistor 205 is a PMOS transistor P1, and the third switch transistor 204 is an NMOS transistor N1. Magnetic beads include L1 and L2.

Wherein, the source of the PMOS tube P1 and the V of the CPU 102_USBThe drain electrode is connected with the D-pin of the USB interface, and the grid electrode (namely the control end) is connected with the VBUS lead wire of the USB interface; the source of the NMOS transistor N1 is connected with the power management chip, and the drain is connected with the V of the CPU 102_USBThe pin is connected, and the grid (namely the control end) is connected with the VBUS of the USB interface; the source of the NMOS transistor N2 is connected to the D-pin of the USB interface, the drain is connected to the OVP, and the gate (i.e., control terminal) is connected to the VBUS pin of the USB interface. One end of the transient voltage suppression diode T1 is connected with the D + pin of the USB interface, the other end is grounded, one end of the transient voltage suppression diode T2 is connected with the D-pin of the USB interface, and the other end is grounded.

Transient voltage suppression diode T3 has one terminal connected to the OVP and the other terminal connected to ground. Transient voltage suppression diode T4 has one terminal connected to the OVP and the other terminal connected to ground. One end of the magnetic bead L1 is connected with the OVP, the other end is connected with the CPU, one end of the magnetic bead L2 is connected with the OVP, and the other end is connected with the CPU.

When the circuit protection circuit works, when abnormal voltage is input outside, taking static as an example, the static can enter the mobile terminal through the USB interface, the first-stage protection circuit 103 can clamp the static, the static voltage is rapidly reduced, and the clamping voltage is usually more than 16V; when clamping voltage is input into the OVP, overvoltage protection operation is carried out, different CPUs have different requirements on input voltage and have different protection voltage on the OVP, and when the OVP is triggered, output voltage is limited so as to protect subsequent loads; the main board side is used for protecting the abnormal introduction (such as electrostatic introduction) of the main board end, the working principle of the main board side is the same as that of a USB interface, and the voltage is rapidly reduced to realize protection.

The circuit protection circuit adopts a three-stage protection circuit design, the first stage protection adopts a TVS device, the second stage protection adopts an overvoltage protection device OVP, and the third stage protection adopts a TVS device, wherein the first stage protection and the second stage protection are arranged on the radio frequency small plate side of the mobile terminal, and the third stage protection is arranged on the main plate side of the mobile terminal. Since the user is operating a USB interface (such as a Type-C interface) on the side of the rf board, it is more advantageous to provide two levels of protection at the board. The protection is carried out to the maximum extent before the main board is carried out on abnormal voltage or current, then a stage is arranged on the side of the main board so as to carry out the maximum protection on the USB circuit, the optimal protection effect is achieved, and meanwhile, the cost is well controlled by the third stage; the magnetic beads are designed to filter electromagnetic interference under D + and D-high-speed transmission data.

Meanwhile, if the USB circuit is damaged (if the USB circuit cannot be charged and cannot be connected with a computer), the circuit protection circuit can also help a maintenance engineer to quickly locate whether the problem occurs in the CPU of the core chip, and the specific detection is as follows:

the method comprises the steps that a low level is input to the VBUS side of a USB data line end, the low level is input to the grid electrodes of an NMOS and a PMOS, so that a PMOS tube P1 is opened, NMOS tubes N1 and N2 are closed, disconnection of a PM and a CPU is achieved, then the impedance of the USB side D-to-ground is tested, if the impedance is low, the CPU is abnormal, if the impedance is normal, the power management chip PM is abnormal, only the targeted device needs to be replaced according to the result, and the efficiency is improved.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element identified by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (such as a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A line protection circuit is used in an intelligent mobile terminal, and the intelligent mobile terminal comprises: interface circuit and central processing unit, wherein connect through data transmission line between interface circuit and the central processing unit, characterized in that, the circuit protection circuit includes at least: the first-stage protection circuit and the second-stage protection circuit are used for protecting abnormal voltage or current, the first-stage protection circuit and the second-stage protection circuit are sequentially connected to the data transmission line from the interface circuit to the central processing unit, and the types of the first-stage protection circuit and the second-stage protection circuit are different;

the interface circuit, the first-stage protection circuit and the second-stage protection circuit are arranged on a first circuit board, and the central processing unit is arranged on a second circuit board which is different from and separated from the first circuit board;

wherein the second stage protection circuit comprises: an overvoltage protection circuit; the overvoltage protection circuit includes: an overvoltage protection device OVP;

wherein the line protection circuit further comprises: the third-stage protection circuit is connected to the data transmission line between the second-stage protection circuit and the central processing unit;

the first stage protection circuit includes: a transient voltage suppression diode;

the third stage protection circuit includes: a transient voltage suppression diode;

wherein the line protection circuit further comprises: the magnetic beads are connected to the data transmission line between the third-stage protection circuit and the central processing unit;

the first-stage protection circuit and the second-stage protection circuit are placed on the radio frequency panel side of the mobile terminal, and the third-stage protection circuit is placed on the main panel side of the mobile terminal.

2. The line protection circuit of claim 1, wherein the first stage protection circuit and the second stage protection circuit are disposed on a first circuit board, and the central processor and the third stage protection circuit are disposed on a second circuit board that is different and separate from the first circuit board.

3. The line protection circuit of claim 1, wherein the data transmission line is a single data transmission line or a dual data transmission line that transmits differential signals.

4. The line protection circuit of claim 1, wherein the interface circuit is a USB interface, and wherein the USB interface comprises: VBUS pin, D + pin, D-pin, the data transmission line includes: the D + pin and the D-pin are respectively connected to the central processor through the first data transmission line and the second data transmission line;

wherein the first switching transistor is connected in series on the second data transmission line;

wherein the second switching transistor is connected in series with V of the CPU_USBThe pin and the D-pin;

wherein the third switching transistor is connected in series with V of the CPU_USBBetween the pin and the power management chip;

5. The line protection circuit of claim 1, wherein the interface circuit is a USB interface, and wherein the USB interface comprises: VBUS pin, D + pin, D-pin, the data transmission line includes: the D + pin and the D-pin are respectively connected to the central processor through the first data transmission line and the second data transmission line; the first stage protection circuit comprises transient voltage suppression diodes T1, T2;

wherein the transient voltage suppression diode T1 is connected to the D + pin and ground; the first switching transistor is connected in series on the second data transmission line; the transient voltage suppression diode T2 is connected with the D pin and the ground;

the second switching transistor is connected between a VUSB pin of the central processing unit and the D-pin in series;

the third switching transistor is connected between a VUSB pin of the central processing unit and the power management chip in series;

6. The line protection circuit of claim 4, wherein when the interface circuit cannot operate normally, determining whether the central processing unit is abnormal and the power management chip is abnormal by turning off the first and third switching transistors and turning on the second switching transistor to detect an impedance to ground of a D-pin of the USB interface.