Interface protection circuit and terminal equipment

Abstract

The utility model discloses an interface protection circuit and a terminal device, the interface protection circuit is connected with a USB interface, a fast charging chip and a control circuit, the interface protection circuit comprises a first-level protection module, a second-level protection module and a third-level protection module; the first-stage protection module is connected with the USB interface and the second-stage protection module, the second-stage protection module is connected with the third-stage protection module and the control circuit, and the third-stage protection module is connected with the fast charging chip; the first-stage protection module is used for performing first-stage surge prevention; the secondary protection module is used for performing secondary surge prevention and performing port burning prevention according to a first control signal output by the control circuit; and the third-stage protection module performs reverse connection prevention and overvoltage protection according to a second control signal output by the fast charging chip. According to the interface protection circuit, surge prevention, reverse connection prevention, port burning prevention and overvoltage protection of the USB interface are realized, and the problem that the existing USB interface does not have various protections is solved.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, in particular to an interface protection circuit and terminal equipment. Background Art

[0002] When a mobile phone is plugged into a charger for charging, due to abnormal fluctuations in the power grid or abnormalities in the charger itself, surge voltage and current may be generated on the power supply VBUS of the mobile phone's USB interface. Therefore, in order to verify the protection capability of the mobile phone against such abnormal surges, it is necessary to perform a surge test on the USB interface, usually testing to ±300V or higher voltage. In order to prevent damage to the mobile phone, it is necessary to add surge protection measures. The conventional design is a circuit composed of a TVS (Transient Voltage Suppressor) and an OVP (Over Voltage Protection) chip. However, when a mobile phone requires high-current fast charging (ChargerPump charging, generally above 30W), a high-current OVP chip is required, which is more expensive.

[0003] In addition, the USB interface of the mobile phone also needs to be designed with protection circuits such as anti-reverse connection, anti-burning, and overvoltage protection.

[0004] Therefore the prior art still needs to be improved and enhanced. Utility Model Content

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an interface protection circuit and a terminal device to solve the problem that the existing USB interface does not have multiple protections.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] An interface protection circuit connects a USB interface, a fast charging chip and a control circuit, and includes a primary protection module, a secondary protection module and a tertiary protection module; the primary protection module connects the USB interface and the secondary protection module, the secondary protection module connects the tertiary protection module and the control circuit, and the tertiary protection module connects the fast charging chip;

[0008] The primary protection module is used for primary surge protection;

[0009] The secondary protection module is used for secondary surge protection and burn protection according to the first control signal output by the control circuit;

[0010] The three-level protection module performs reverse connection and overvoltage protection according to the second control signal output by the fast charging chip.

[0011] In the interface protection circuit, the primary protection module includes a TVS tube and a diode; the cathode of the TVS tube is connected to the power pin of the USB interface, the cathode of the diode and the secondary protection module; the anode of the TVS tube is connected to the ground pin of the USB interface, the anode of the diode and the secondary protection module.

[0012] In the interface protection circuit, the first-level protection module also includes a first capacitor, one end of the first capacitor is connected to the cathode of the diode and the second-level protection module, and the other end of the first capacitor is connected to the anode of the diode and the second-level protection module.

[0013] In the interface protection circuit, the secondary protection module includes a first switch tube and a second capacitor, the gate of the first switch tube inputs a first control signal, the drain of the first switch tube is connected to one end of the second capacitor, one end of the first capacitor and the tertiary protection module; the source of the first switch tube is connected to the ground pin of the USB interface and the other end of the second capacitor.

[0014] In the interface protection circuit, the three-level protection module includes a second switch tube and a third switch tube, the drain of the second switch tube is connected to the drain of the first switch tube, the source of the second switch tube is connected to the source of the third switch tube, the gate of the second switch tube is connected to the gate of the third switch tube and inputs the second control signal; the drain of the third switch tube is a voltage input terminal.

[0015] In the interface protection circuit, the three-level protection module also includes a third capacitor, one end of the third capacitor is connected to the drain of the third switch tube, and the other end of the third capacitor is connected to the source of the first switch tube and the ground on the circuit board.

[0016] In the interface protection circuit, the secondary protection module also includes a fourth capacitor, one end of the fourth capacitor is connected to the gate of the first switch tube, and the other end of the fourth capacitor is connected to the source of the first switch tube and the ground pin of the USB interface.

[0017] A terminal device includes a circuit board, on which a USB interface, a fast charging chip and a control circuit are integrated, wherein the circuit board is also integrated with the interface protection circuit; the interface protection circuit is connected to the USB interface, the fast charging chip and the control circuit; the USB interface is connected to the fast charging chip and the control circuit;

[0018] The fast charging chip detects the power supply voltage input by the USB interface and outputs a second control signal of a corresponding level, and the control circuit detects the working state of the USB interface and outputs a first control signal of a corresponding level;

[0019] The interface protection circuit controls the output state of the power supply voltage according to the first control signal and the second control signal, and performs surge protection, reverse connection protection, burn-out protection and overvoltage protection on the USB interface.

[0020] Compared with the prior art, the interface protection circuit and terminal equipment provided by the utility model, the interface protection circuit connects the USB interface, the fast charging chip and the control circuit, and the interface protection circuit includes a primary protection module, a secondary protection module and a tertiary protection module; the primary protection module connects the USB interface and the secondary protection module, the secondary protection module connects the tertiary protection module and the control circuit, and the tertiary protection module connects the fast charging chip; the primary protection module is used for primary surge protection; the secondary protection module is used for secondary surge protection and also performs burn protection according to the first control signal output by the control circuit; the tertiary protection module performs reverse connection and overvoltage protection according to the second control signal output by the fast charging chip. The interface protection circuit realizes surge protection, reverse connection protection, burn protection and overvoltage protection for the USB interface, solving the problem that the existing USB interface does not have multiple protections. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural block diagram of the terminal device provided by the utility model.

[0022] Figure 2 The utility model provides a circuit diagram of an interface protection circuit. DETAILED DESCRIPTION

[0023] The utility model provides an interface protection circuit and a terminal device. In order to make the purpose, technical solution and advantages of the utility model clearer and more specific, the utility model is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0024] Please also see Figure 1 and Figure 2 The terminal device provided by the utility model includes a circuit board, on which a USB interface, a fast charging chip 10, a control circuit 20 and an interface protection circuit 30 are integrated; the interface protection circuit 30 is connected to the USB interface, the fast charging chip 10 and the control circuit 20; the USB interface is connected to the fast charging chip 10 and the control circuit 20. The fast charging chip 10 detects the power supply voltage VIN+ input by the USB interface and outputs a second control signal GPIO2 of a corresponding level, the control circuit 20 detects the working state of the USB interface and outputs a first control signal GPIO1 of a corresponding level, and the interface protection circuit 30 controls the output state of the power supply voltage VIN+ according to the first control signal GPIO1 and the second control signal GPIO2, and performs surge protection, reverse connection protection, burn-out protection and overvoltage protection on the USB interface.

[0025] Among them, the peripherals connected to the USB interface through the data cable include a charger and a computer, and a U disk can also be directly inserted. After the peripheral is inserted, the power pin (VCC pin or VBUS pin, the pin name is related to the specific type) of the USB interface is connected to the power pin of the peripheral, the ground pin (GND pin) of the USB interface is connected to the ground pin of the peripheral, and the data pin of the USB interface is connected to the data pin of the peripheral. The fast charging chip 10 detects whether the power supply voltage VIN+ input by the USB interface is normal. Abnormalities include overvoltage if the voltage value is too high, and reverse connection if it is a low level. The second control signal GPIO2 can be output to achieve anti-reverse connection and overvoltage protection. The control circuit 20 detects the working status of the USB interface, preferably detecting whether the temperature of the USB interface is normal. If it is too high, the first control signal GPIO1 is output to prevent burning.

[0026] The terminal device is all fast-charging mobile phones with a charge pump (Charger Pump), or other USB devices that support detecting VBUS and controlling NMOS tubes. The circuit structure of the fast-charging chip 10 (preferably SC8549, the specific model is not limited here) and the processor and the above-mentioned functions are prior art. The power pin of the USB interface is connected to the detection pin (VAC pin) of the fast-charging chip 10 and the corresponding detection pin of the control circuit (preferably CPU (central processing unit) or PMIC (power management chip)), so that the fast-charging chip 10 and the control circuit can perform corresponding detection. This embodiment mainly uses the first control signal GPIO1 (provided by the GPIO pin) output by the control circuit and the second control signal GPIO2 (provided by the OVPGATE pin, the pin names of other models are changed accordingly) output by the fast-charging chip 10 to perform on-off control of the power supply voltage VIN+ output path; the specific circuit structure of the fast-charging chip 10 and the control circuit is not limited. The output end of the interface protection circuit 30 is the voltage input end of the entire circuit board, and outputs the supply voltage VOUT± for power supply. The subsequent stage can be connected to the existing circuit modules and power supply circuits that need power supply (the supply voltage VOUT± is stepped up or down to other voltage values).

[0027] The interface protection circuit 30 includes a primary protection module 31, a secondary protection module 32 and a tertiary protection module 33; the primary protection module is connected to the USB interface and the secondary protection module, the secondary protection module is connected to the tertiary protection module and the control circuit, and the tertiary protection module is connected to the fast charging chip; the primary protection module 31 is used for primary surge protection; the secondary protection module 32 is used for secondary surge protection and also performs burn-out protection according to the input first control signal GPIO1; the tertiary protection module 33 performs reverse connection protection and overvoltage protection according to the input second control signal GPIO2.

[0028] The primary protection module 31 includes a TVS tube T1 and a diode D1; the cathode of the TVS tube T1 is connected to the power pin of the USB interface, the cathode of the diode D1 and the secondary protection module 32; the anode of the TVS tube T1 is connected to the ground pin of the USB interface, the anode of the diode D2 and the secondary protection module 32.

[0029] When the TVS tube T1 is reversely broken down by a positive surge, it can absorb most of the surge voltage; when it is forward-conducted by a negative surge, it provides a circuit for releasing the negative surge to the ground, thereby playing a surge protection function. The diode D1 is a Schottky diode.

[0030] The primary protection module 31 also includes a first capacitor C1, one end of which is connected to the cathode of the diode D1 and the secondary protection module 32, and the other end of the first capacitor C1 is connected to the anode of the diode D2 and the secondary protection module 32. The first capacitor C1 is used to absorb the residual pressure of the TVS tube T1 after surge protection, that is, the instantaneous surge current charges the first capacitor C1. When the TVS tube T1 and the diode D1 are forward-conducted, the electric energy stored in the first capacitor C1 can be discharged to the ground.

[0031] The secondary protection module 32 includes a first switch tube Q1 and a second capacitor C2, the gate G of the first switch tube Q1 inputs the first control signal GPIO1, the drain D of the first switch tube Q1 is connected to one end of the second capacitor C2, one end of the first capacitor C1 (or the negative electrode of the diode D1) and the tertiary protection module 33; the source S of the first switch tube Q1 is connected to the ground pin of the USB interface and the other end of the second capacitor C2.

[0032] Wherein, the first switch tube Q1 is preferably an N-MOS tube, Q1 is turned on when the first control signal GPIO1 is at a high level, and Q1 is turned off when it is at a low level. When there is no first control signal GPIO1 input and there is a negative surge, the body diode inside Q1 is forward-conducted, and the source S and drain D of Q1 are turned on. The second capacitor C2 is used to absorb the residual voltage of Q1 after surge protection.

[0033] Preferably, the secondary protection module 32 further includes a fourth capacitor C4, one end of which is connected to the gate G of the first switch tube Q1, and the other end of which is connected to the source S of the first switch tube Q1 and the ground pin of the USB interface. The fourth capacitor C4 is used to filter out interference on the gate of Q1 to prevent Q1 from being mis-conducted.

[0034] The three-level protection module 33 includes a second switch tube Q2 and a third switch tube Q3, wherein the drain D of the second switch tube Q2 is connected to the drain D of the first switch tube Q1, the source S of the second switch tube Q2 is connected to the source S of the third switch tube Q3, the gate G of the second switch tube Q2 is connected to the gate G of the third switch tube Q3 and inputs the second control signal GPIO2; the drain D of the third switch tube Q3 is a voltage input terminal.

[0035] The second switch tube Q2 and the third switch tube Q3 are preferably N-MOS tubes, and Q2 and Q3 are turned on when the second control signal GPIO2 is at a high level, and are turned off when the second control signal GPIO2 is at a low level.

[0036] Preferably, the three-level protection module 33 further includes a third capacitor C3, one end of the third capacitor C3 is connected to the drain D of the third switch tube Q3, and the other end of the third capacitor C3 is connected to the source S of the first switch tube Q1 and the ground on the circuit board. The third capacitor C3 is used to filter the output power supply voltage VOUT+ to make its power supply more stable.

[0037] In this embodiment, the working principle of the interface protection circuit 10 to realize the surge protection function is:

[0038] When a positive surge occurs, the TVS tube T1 at the front end is reversely broken down and absorbs most of the surge. At the same time, the fast charging chip 10 detects overvoltage and outputs a high-level second control signal GPIO2, disconnects the second switch tube Q2 and the third switch tube Q3. At this time, there is no power supply voltage output, which can protect the subsequent circuit. The first capacitor C1 is used to absorb the residual voltage after the TVS tube T1.

[0039] When a negative surge occurs, the front-end TVS tube T1 and diode D1 are used for the first-level surge protection. T1 and D1 are forward-conducted to provide a release circuit for the negative surge, and the first capacitor C1 absorbs the residual voltage of the first-level surge protection. The first switch tube Q1 is used for the second-level surge protection, and its body diode is forward-conducted to provide a release circuit for the residual negative surge. The current flows from the source S of Q1 to the drain D, and then flows back to the surge source through the power pin VIN+ of the USB interface. The second capacitor C2 is used to absorb the residual voltage after the second-level surge protection.

[0040] During the surge protection process, the on and off of the second switch tube Q2 and the third switch tube Q3 are related to the charging state and are controlled by the second control signal GPIO2 output by the fast charging chip 10; that is, when in the charging state, Q2 and Q3 are turned on; when not charging or charging stops, Q2 and Q3 are turned off.

[0041] The working principle of the interface protection circuit 10 to realize the anti-reverse connection function is: when the USB interface is normally connected to a USB device (charger or PC, etc.), the fast charging chip (ChargerPump) detects that the power supply voltage VIN+ on the power pin of the USB interface is normal (normal within the voltage range of 3.5 to 12V, and the specific value depends on the battery and the charging scheme), and outputs a high-level second control signal GPIO2 to turn on Q2 and Q3. The power supply voltage VIN+ on the power pin of the USB interface is output as the power supply voltage VOUT+ through Q2 and Q3 to realize charging.

[0042] When the device plugged into the USB interface is connected in reverse, the fast charging chip detects that the voltage on the power pin of the USB interface is abnormal (the detected voltage is negative at this time, which exceeds the normal voltage range), and outputs a low-level second control signal GPIO2 to control Q2 and Q3 to be turned off. And because the body diodes of the two MOS tubes Q2 and Q3 are in opposite directions and will not be turned on, the anti-reverse connection function is realized.

[0043] The working principle of the interface protection circuit 10 to realize the anti-burning function is as follows: when the control circuit 20 detects that the temperature of the USB interface is too high, the first control signal GPIO1 outputs a high level to control the first switch tube Q1 to turn on, the power supply voltage VIN+ stops outputting, charging is turned off, and the charging short circuit protection is triggered to prevent the USB interface from being burned. It should be understood that the temperature detection function of the USB interface is a prior art. For example, on a circuit board, an NTC resistor is set near the USB interface. The control circuit 20 collects the voltage value on the NTC resistor to obtain the corresponding temperature value. If the voltage value is within the normal range, the temperature is normal. If it exceeds the normal range, the temperature is too high.

[0044] The working principle of the interface protection circuit 10 to realize the overvoltage protection function is: when the fast charging chip detects that the voltage on the power pin of the USB interface is greater than the upper limit threshold, the second control signal GPIO2 with a low level is output to shut down Q2 and Q3, and the power supply voltage VIN+ stops being output, thereby realizing overvoltage protection.

[0045] In a specific charging process, the control circuit 20 can also control the first switch tube Q1 to be turned off according to the user's needs to set the working state of the USB interface, so as to realize the short-circuit protection function of other state detection.

[0046] For example, when charging at a specific voltage, the control circuit 20 detects that the power voltage VIN+ on the power pin of the USB interface is a set voltage value, and controls Q1 to be turned off; combined with the fast charging chip, Q2 and Q3 are controlled to be turned on, and charging is then started; when the control circuit 20 detects that the change in the power voltage VIN+ exceeds the set range, Q1 is controlled to be turned on, and charging is stopped.

[0047] For timed charging, the control circuit 20 controls Q1 to turn on and stop charging after detecting that the internal preset charging time has been reached; or controls Q1 to turn on and off accordingly according to the set charging start and stop time, so as to realize alternating charging or stopping charging.

[0048] Specific temperature charging has the same function as the anti-burning port, with the addition that when the temperature is detected to be lower than the normal range, Q1 is controlled to turn on and stop charging.

[0049] To charge or stop charging in a specific light environment, the control circuit 20 detects the intensity of the ambient light and charges or stops charging at a set intensity.

[0050] The user uses the set scene to charge or stop charging. The user defines the content of the set scene. When the control circuit 20 detects that the user uses certain set scenes, it controls charging or stopping charging.

[0051] To sum up, the interface protection circuit and terminal equipment of the utility model, while supporting high-power charging, use N-MOS tubes, Schottky diodes and capacitors to form a multifunctional protection circuit: the circuit structure is simple, fewer devices are used, and costs are saved. At the same time, it is also compatible with protection functions such as surge protection, reverse connection protection, burn-out protection and overvoltage protection.

[0052] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made according to the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. An interface protection circuit, connecting a USB interface, a fast charging chip and a control circuit, characterized in that: It includes a primary protection module, a secondary protection module and a tertiary protection module; the primary protection module is connected to the USB interface and the secondary protection module, the secondary protection module is connected to the tertiary protection module and the control circuit, and the tertiary protection module is connected to the fast charging chip; The primary protection module is used for primary surge protection; The secondary protection module is used for secondary surge protection and burn protection according to the first control signal output by the control circuit; The three-level protection module performs reverse connection and overvoltage protection according to the second control signal output by the fast charging chip.

2. The interface protection circuit according to claim 1, characterized in that: The primary protection module includes a TVS tube and a diode; the cathode of the TVS tube is connected to the power pin of the USB interface, the cathode of the diode and the secondary protection module; the anode of the TVS tube is connected to the ground pin of the USB interface, the anode of the diode and the secondary protection module.

3. The interface protection circuit according to claim 2, characterized in that: The primary protection module further includes a first capacitor, one end of which is connected to the cathode of the diode and the secondary protection module, and the other end of which is connected to the anode of the diode and the secondary protection module.

4. The interface protection circuit according to claim 3, characterized in that: The secondary protection module includes a first switch tube and a second capacitor, the gate of the first switch tube inputs a first control signal, the drain of the first switch tube is connected to one end of the second capacitor, one end of the first capacitor and the tertiary protection module; the source of the first switch tube is connected to the ground pin of the USB interface and the other end of the second capacitor.

5. The interface protection circuit according to claim 4, characterized in that: The three-level protection module includes a second switch tube and a third switch tube, the drain of the second switch tube is connected to the drain of the first switch tube, the source of the second switch tube is connected to the source of the third switch tube, the gate of the second switch tube is connected to the gate of the third switch tube and inputs the second control signal; the drain of the third switch tube is a voltage input terminal.

6. The interface protection circuit according to claim 5, characterized in that: The three-level protection module also includes a third capacitor, one end of which is connected to the drain of the third switch tube, and the other end of which is connected to the source of the first switch tube and the ground on the circuit board.

7. The interface protection circuit according to claim 4, characterized in that: The secondary protection module also includes a fourth capacitor, one end of which is connected to the gate of the first switch tube, and the other end of which is connected to the source of the first switch tube and the ground pin of the USB interface.

8. A terminal device, comprising a circuit board, on which a USB interface, a fast charging chip and a control circuit are integrated, characterized in that: The circuit board also integrates the interface protection circuit as described in any one of claims 1 to 7; the interface protection circuit is connected to the USB interface, the fast charging chip and the control circuit; the USB interface is connected to the fast charging chip and the control circuit; The fast charging chip detects the power supply voltage input by the USB interface and outputs a second control signal of a corresponding level, and the control circuit detects the working state of the USB interface and outputs a first control signal of a corresponding level; The interface protection circuit controls the output state of the power supply voltage according to the first control signal and the second control signal, and performs surge protection, reverse connection protection, burn-out protection and overvoltage protection on the USB interface.

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