WO2018103574A1 - 过欠压保护电路和机顶盒 - Google Patents

过欠压保护电路和机顶盒 Download PDF

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Publication number
WO2018103574A1
WO2018103574A1 PCT/CN2017/113744 CN2017113744W WO2018103574A1 WO 2018103574 A1 WO2018103574 A1 WO 2018103574A1 CN 2017113744 W CN2017113744 W CN 2017113744W WO 2018103574 A1 WO2018103574 A1 WO 2018103574A1
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Prior art keywords
voltage
resistor
transistor
power supply
input
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PCT/CN2017/113744
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English (en)
French (fr)
Inventor
丁前利
潘庆思
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深圳创维数字技术有限公司
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Publication of WO2018103574A1 publication Critical patent/WO2018103574A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/24—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to undervoltage or no-voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/41—Structure of client; Structure of client peripherals
    • H04N21/426—Internal components of the client ; Characteristics thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/63—Generation or supply of power specially adapted for television receivers

Definitions

  • the present disclosure relates to circuit protection techniques, such as to an overvoltage and undervoltage protection circuit and a set top box.
  • the failure rate of the failure is the highest, and the cause of the failure is that the power supply chip is damaged.
  • the reason for the above power supply chip damage is that the regional power grid is unstable, the voltage fluctuation is large, and there are often power failures and incoming calls, which causes the input voltage of the adapter to increase instantaneously, so that the DC-DC in the power supply chip (Direct Current) -Direct Current, DC-DC)
  • the power supply circuit damage frequency increases.
  • TVS Transient Voltage Suppressor
  • electrolytic capacitors the reaction speed of the incoming high-voltage TVS tube may not keep up, and the electrolytic capacitor cannot be used for instantaneous high voltage.
  • the residual voltage after the above protection device also damages the DC-DC power supply circuit in the power supply chip.
  • the present disclosure provides an overvoltage and undervoltage protection circuit and a set top box to protect the set-top box's DC-DC power supply circuit when the input voltage is too high or too low.
  • An overvoltage and undervoltage protection circuit includes:
  • the voltage judging module is configured to be connected to the voltage input terminal for detecting the input voltage range and rooting Outputting a control signal according to the input voltage range;
  • control module configured to: control disconnection and conduction between the voltage input terminal and the DC-DC power supply circuit according to the control signal of the voltage determination module.
  • the voltage determining module includes:
  • a first resistor and a second resistor are connected in series between the voltage input terminal and the low potential point, and a first potential control point is formed between the first resistor and the second resistor;
  • a fourth resistor and a fifth resistor are connected in series between the voltage input terminal and the low potential point, and a second potential control point is formed between the fourth resistor and the fifth resistor;
  • a base of the first transistor is connected to the first potential control point through a third resistor, and a collector and an emitter of the first transistor are connected in series at a second potential control point And the low voltage point, the first transistor is arranged to control the conduction and disconnection of the first transistor according to the voltage of the first potential control point;
  • a base of the second transistor is connected to a collector of the first transistor through a sixth resistor, a collector of the second transistor and a portion of the control module Connected to one end, the second transistor is arranged to control the conduction and disconnection of the second transistor through the voltage of the second potential control point.
  • control module includes:
  • a metal oxide semiconductor MOS transistor a gate of the MOS transistor is connected to the voltage input terminal through a seventh resistor, and an output terminal of the voltage determining module is connected to a source of the MOS transistor through the eighth resistor a voltage input end is connected, a drain of the MOS transistor is connected to the DC-DC power supply circuit, and the MOS transistor is configured to control the MOS according to an input voltage of the voltage input end and a control signal of the voltage determination module The working state of the pipe.
  • the circuit further includes:
  • the LED light is connected to the output end of the voltage judging module, and is configured to control the working state of the LED lamp according to the control signal of the voltage judging module.
  • resistance values of the first resistor and the second resistor connected in series are such that a voltage of the first potential control point is less than a conduction threshold of the transistor, The first transistor is disconnected; when the input voltage is greater than a maximum value of the preset voltage range, the resistances of the first resistor and the second resistor connected in series cause the voltage of the first potential control point to be greater than a conduction threshold of the triode, the first triode being turned on;
  • the resistance values of the fourth resistor and the fifth resistor connected in series are such that a voltage of the second potential control point is smaller than a conduction threshold of the transistor, The second triode is disconnected.
  • a set top box includes a voltage input terminal, a DC-DC DC-DC power supply circuit, and an overvoltage and undervoltage protection circuit provided by the embodiment.
  • the overvoltage and undervoltage protection circuit is connected to the voltage input terminal and the DC-DC power supply circuit. between.
  • the present invention obtains whether the voltage range input by the voltage input terminal is in the preset voltage range of the DC-DC power supply circuit through the voltage judging module, and outputs a control signal, and the control module is connected with the voltage judging module, and controls the voltage input end according to the control signal.
  • the disconnection and conduction between the DC-DC power supply circuits that is, the addition of an undervoltage protection circuit between the voltage input terminal and the DC-DC power supply circuit replaces the voltage input terminal and the DC-DC power supply circuit in the related art. Directly connected, solves the problem that the DC-DC power supply circuit is damaged when the input voltage is too high or too low, and protects the DC-DC power supply circuit when the input voltage is too high or too low.
  • FIG. 1 is a structural view of an overvoltage and undervoltage protection circuit in the embodiment
  • FIG. 2 is a structural diagram of a voltage judging module of an overvoltage and undervoltage protection circuit in the embodiment
  • 3A is a structural diagram of a control module of an overvoltage and undervoltage protection circuit in the embodiment
  • FIG. 3B is a structural diagram of another overvoltage and undervoltage protection circuit in the embodiment.
  • FIG. 4 is a schematic structural diagram of a set top box according to the embodiment.
  • FIG. 1 is a structural diagram of an over-voltage and under-voltage protection circuit according to an embodiment of the present invention.
  • the embodiment is applicable to a case where a protection power supply circuit is not damaged when an input voltage is too high or too low, and the circuit can be integrated into a power supply.
  • the equipment of the power supply circuit is especially suitable for use in a set top box.
  • the output of the overvoltage and undervoltage protection circuit is connected to the power supply circuit.
  • the overvoltage and undervoltage protection circuit provided in this embodiment includes a voltage determination module 110 and a control module 120.
  • the voltage judging module 110 is configured to be connected to the voltage input end for detecting the input voltage range, and outputting the control signal according to the input voltage range;
  • the control module 120 is configured to be connected to the output end of the voltage judging module 110, and the second The terminal is connected to the voltage input end, and the third end is connected to the DC-DC power supply circuit for controlling the disconnection and conduction between the voltage input terminal and the DC-DC power supply circuit according to the control signal of the voltage determination module 110.
  • the DC-DC power supply circuit when the voltage input terminal is directly connected to the DC-DC power supply circuit, if the input voltage is too high or too low, the DC-DC power supply circuit may be damaged.
  • the voltage judging module 110 is connected to the voltage input end to detect whether the input voltage is within a preset voltage range of the DC-DC power supply circuit, and output a control signal according to the detection result.
  • the control module controls the working state of the DC-DC power supply circuit according to the control signal output by the voltage determination module.
  • the control module controls the DC-DC power supply circuit to be disconnected according to the control signal; when the input voltage is greater than the maximum value of the preset voltage range The control module controls the DC-DC power supply circuit to be disconnected according to the control signal; when the input voltage is within the set voltage range, the control module controls the DC-DC power supply circuit to be turned on according to the control signal, thereby ensuring that when the input voltage is too high or When the voltage is too low, the DC-DC power supply circuit is disconnected, which avoids the problem that the DC-DC power supply circuit is damaged when the input voltage is too high or too low.
  • the voltage input module obtains the voltage input by the voltage input terminal, determines whether the input voltage is in a preset voltage range of the DC-DC power supply circuit, and outputs a control signal, and the control module is connected to the voltage determination module according to the control signal.
  • the control voltage input terminal and the DC-DC power supply circuit are disconnected and turned on, that is, an over-voltage protection circuit is added between the voltage input terminal and the DC-DC power supply circuit to replace the voltage input terminal and the DC in the related art.
  • the DC power supply circuit is directly connected to solve the problem that the DC-DC power supply circuit is damaged when the input voltage is too high or too low, and the DC-DC power supply circuit is protected when the input voltage is too high or too low.
  • FIG. 2 is a structural diagram of the voltage judging module of the overvoltage and undervoltage protection circuit provided in this embodiment.
  • This embodiment is an explanation of the working principle and process of the voltage judging module 110 in the above embodiment.
  • the voltage judging module 110 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first transistor Q1, and a second transistor Q2.
  • the first resistor R1 and the second resistor R2 are connected in series between the voltage input terminal and the low potential point, and a first potential control point A is formed between the first resistor R1 and the second resistor R2.
  • the fourth resistor R4 and the fifth resistor R5 are connected in series between the voltage input terminal and the low potential point, and a second potential control point B is formed between the fourth resistor R4 and the fifth resistor R5.
  • the base of the first transistor Q1 is connected to the first potential control point A through the third resistor R3, and the collector and the emitter of the first transistor Q1 are connected in series between the second potential control point B and the low potential point. Used according to The voltage of the first potential control point A controls the conduction and disconnection of the first transistor Q1.
  • the base of the second transistor Q2 is connected to the collector of the first transistor Q1 through the sixth resistor R6 for controlling the conduction and disconnection of the second transistor Q2 through the voltage of the second potential control point B.
  • the collector of the second transistor Q2 is connected to the first end of the control module 120.
  • the resistance values of the first resistor R1 and the second resistor R2 in series are such that the voltage of the first potential control point A is smaller than the conduction threshold of the triode, the first three The pole tube Q1 is disconnected; when the input voltage is greater than the maximum value of the preset voltage range, the resistance values of the first resistor R1 and the second resistor R2 in series cause the voltage of the first potential control point A to be greater than the conduction threshold of the triode, A transistor Q1 is turned on.
  • the resistance values of the fourth resistor R4 and the fifth resistor R5 connected in series cause the voltage of the second potential control point B to be smaller than the conduction threshold of the transistor, and the second transistor Q2 is broken. open.
  • the voltage of the first potential control point A is smaller than the conduction threshold of the triode
  • the first transistor Q1 is turned off
  • the voltage is the voltage of the fifth resistor R5, the voltage of the second potential control point B is less than the conduction threshold of the transistor, and the second transistor Q2 is turned off
  • the voltage determination module 110 outputs the control signal to the high level; when the input voltage When the value is greater than the maximum value of the preset voltage range, the voltage of the first potential control point A, that is, the voltage of the second resistor R2 is greater than the conduction threshold of the transistor, the first transistor Q1 is turned on, and the voltage of the second potential control point B is 0, less than
  • the voltage values of the first potential control point and the voltage value of the second potential control point respectively control the conduction and disconnection of the first triode and the second triode and the output control signal of the control voltage judging module. That is, when the input voltage is between the normal voltage range and the abnormal voltage range, the control signal of the control output is different, and the control voltage input terminal and the DC-DC power supply circuit are disconnected and turned on, which solves the problem that the input voltage is too high or too high. When the power is low, the DC-DC power supply circuit is damaged, and the DC-DC power supply circuit is protected when the input voltage is too high or too low.
  • FIG. 3A is a structural diagram of a control module for an overvoltage and undervoltage protection circuit according to the embodiment.
  • This embodiment describes the working principle and process of the control module 120.
  • the control module 120 includes metal oxide. Metal Oxide Semiconductor (MOS) tube Q3, seventh resistor R7 and eighth resistor R8.
  • MOS Metal Oxide Semiconductor
  • the gate of the MOS transistor Q3 is connected to the output terminal of the voltage judging module 110 through the eighth resistor R8, and is connected to the voltage input terminal through the seventh resistor R7, and the source of the MOS transistor Q3 is connected to the voltage input terminal, and the MOS transistor Q3 is connected.
  • the drain is connected to the DC-DC power supply circuit, and the MOS transistor Q3 is configured to control the operating state of the MOS transistor Q3 according to the input voltage of the voltage input terminal and the control signal of the voltage determination module 110.
  • the input voltage of the voltage input terminal is a high level
  • the output control signal of the voltage determination module is a high level
  • the gate voltage of the MOS transistor Q3 is a high level.
  • the MOS tube Q3 is disconnected; when the input voltage is greater than the maximum value of the preset voltage range, the input voltage of the voltage input terminal is high level, the output control signal of the voltage judging module is high level, and the gate voltage of the MOS transistor Q3 is When the high level is high, the MOS transistor Q3 is turned off; when the input voltage is within the preset voltage range, the voltage judgment module outputs a control signal to a low level, the voltage input terminal input voltage is a high level, and the gate voltage of the MOS transistor Q3 is When it is low, the MOS transistor Q3 is turned on.
  • the DC-DC power supply circuit when the input voltage is within the preset voltage range
  • the DC-DC power supply circuit is electrically connected to the voltage input terminal, and the DC-DC power supply circuit is in a working state.
  • the DC-DC power supply circuit When the input voltage is outside the preset voltage range, the DC-DC power supply circuit is disconnected from the voltage input terminal.
  • the DC-DC power supply circuit is in a stopped state, which avoids damage to the DC-DC power supply circuit when the input voltage is too high or too low.
  • FIG. 3B is a structural diagram of another over-voltage and under-voltage protection circuit provided by the embodiment.
  • the normal working voltage of the DC-DC power supply circuit can be 12V, and the preset voltage range is 9V to 13.8V. This is explained.
  • the values of the following parameters are only an exemplary value. There may be other values. The values are different.
  • the resistance of each resistor in the overvoltage and undervoltage circuit is different. The relevant adjustment can be made according to the situation.
  • the first resistor R1 and the second resistor R2 connected in series divide the input voltage.
  • the voltage of the first potential control point A that is, the voltage of the second resistor R2 is smaller than the conduction of the transistor.
  • the threshold (for example, may be 0.6V), by way of example, the resistance of the first resistor R1 and the second resistor R2 may be 22K ⁇ and 1K ⁇ .
  • the fourth resistor R4 and the fifth resistor R5 connected in series divide the input voltage.
  • the voltage of the second potential control point B that is, the voltage of the fifth resistor R5 is smaller than the conduction threshold of the transistor.
  • the resistance values of the fourth resistor R4 and the fifth resistor R5 may be 14K ⁇ and 1K ⁇ .
  • the third resistor R3 and the sixth resistor R6 are used for current limiting to prevent damage to the triode when the current is too high.
  • the third resistor R3 and the sixth resistor R6 may each have a value of 10 k ⁇ .
  • the seventh resistor R7 and the eighth resistor R8 connected in series are used for voltage division.
  • the seventh resistor R7 and the eighth resistor R8 may take values of 1 K ⁇ and 2 K ⁇ , respectively.
  • control module controls the turn-on and turn-off of the MOS transistor according to the voltage control module output control signal.
  • the DC-DC power supply circuit and the voltage input terminal are turned on, and the input is solved.
  • the voltage is too high or too low, the DC-DC power supply circuit is damaged, and the DC-DC power supply circuit is protected when the input voltage is too high or too low.
  • the overvoltage and undervoltage protection circuit further includes a light-emitting diode (LED) lamp.
  • LED light-emitting diode
  • the LED lamp is connected to the output end of the voltage judging module, and is configured to control the working state of the LED lamp according to the control signal of the voltage judging module.
  • the voltage at the output terminal of the voltage judging module is greater than 0, and the LED lamp is powered on.
  • the voltage at the output of the voltage judging module is equal to 0, and the LED light is off.
  • the user can obtain whether the current input voltage is in a normal state according to the working condition of the LED lamp, and perform corresponding processing according to the LED light display.
  • the set top box 400 includes a voltage input terminal 410, a DC-DC power supply circuit 430, and any overvoltage and undervoltage protection circuit 420 provided in this embodiment.
  • Circuit 420 is coupled between voltage input terminal 410 and DC-DC power supply circuit 430.
  • the voltage input terminal is directly connected to the DC-DC power supply circuit by adding an over-voltage protection circuit between the voltage input terminal and the DC-DC power supply circuit, thereby solving the problem that the input voltage is too high or too high.
  • the DC-DC power supply circuit is damaged, the set-top box cannot be turned on.
  • the DC-DC power supply circuit can be protected when the input voltage is too high or too low to ensure the normal operation of the set-top box.
  • the over-voltage protection circuit and the set-top box provided by the present disclosure solve the problem that the power supply circuit of the DC-DC power supply is damaged and the set-top box cannot be turned on when the input voltage is too high or too low, and the DC is protected when the input voltage is too high or too low.
  • -DC power supply circuit to ensure the normal operation of the set-top box.

Abstract

一种过欠压保护电路，包括：电压判断模块，设置为与电压输入端相连，用于检测输入电压范围，并根据所述输入电压范围输出控制信号；控制模块，第一端与所述电压判断模块的输出端相连，第二端设置为与所述电压输入端相连，第三端设置为与DC-DC电源供电电路相连，所述控制模块设置为：根据所述电压判断模块的控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通。

Description

过欠压保护电路和机顶盒 技术领域
本公开涉及电路保护技术，例如涉及一种过欠压保护电路和机顶盒。
背景技术
随着机顶盒的不断发展，机顶盒的海外市场占据着重要的分量。
根据海外市场故障分析可知，不开机故障占全部故障的比例较高，导致发生不开机故障的原因是电源供电芯片损坏。上述电源供电芯片损坏问题的原因是地区电网不稳定，电压波动较大，经常有断电与来电的情况，导致适配器的输入电压会瞬间增大，使得电源供电芯片中的直流-直流(Direct Current-Direct Current，DC-DC)电源供电电路损坏频率增大。
针对上述问题，可以通过瞬变电压抑制二极管(Transient Voltage Suppressor，TVS)和大的电解电容进行保护，但是，来电的瞬时高压TVS管的反应速度可能跟不上，并且电解电容也不能对瞬时高压进行保护，经过上述保护器件后的残压同样会损坏电源供电芯片中的DC-DC电源供电电路。
发明内容
本公开提供一种过欠压保护电路和机顶盒，以在输入电压过高或过低时保护机顶盒的DC-DC电源供电电路。
一种过欠压保护电路，包括：
电压判断模块，设置为与电压输入端相连，用于检测输入电压范围，并根 据所述输入电压范围输出控制信号；
控制模块，第一端与所述电压判断模块的输出端相连，第二端设置为与所述电压输入端相连，第三端设置为与直流-直流DC-DC电源供电电路相连，所述控制模块设置为：根据所述电压判断模块的控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通。
可选地，所述电压判断模块包括：
第一电阻和第二电阻，串联在所述电压输入端和低电位点之间，所述第一电阻和第二电阻之间形成有第一电位控制点；
第四电阻和第五电阻，串联在所述电压输入端和低电位点之间，所述第四电阻和第五电阻之间形成有第二电位控制点；
第一三极管，所述第一三极管的基极通过第三电阻与所述第一电位控制点相连，所述第一三极管的集电极和发射极串联在第二电位控制点和低电位点之间，所述第一三极管设置为根据所述第一电位控制点的电压控制所述第一三极管的导通和断开；
第二三极管，所述第二三极管的基极通过第六电阻与所述第一三极管的集电极相连，所述第二三极管的集电极与所述控制模块的第一端相连，第二三极管设置为通过所述第二电位控制点的电压控制所述第二三极管的导通和断开。
可选地，所述控制模块包括：
金属氧化物半导体MOS管，所述MOS管的栅极通过第七电阻与所述电压输入端相连，通过第八电阻与所述电压判断模块的输出端相连所述MOS管的源极与所述电压输入端相连，所述MOS管的漏极与所述DC-DC电源供电电路相连，所述MOS管设置为根据所述电压输入端的输入电压与所述电压判断模块的控制信号控制所述MOS管的工作状态。
可选地，所述电路还包括：
发光二极管LED灯，所述LED灯与所述电压判断模块的输出端相连，设置为根据所述电压判断模块的控制信号控制所述LED灯的工作状态。
可选地，在所述输入电压小于预设电压范围的最小值时，串联的所述第一电阻和第二电阻的阻值使得所述第一电位控制点的电压小于三极管的导通阈值，所述第一三极管断开；在所述输入电压大于预设电压范围的最大值时，串联的所述第一电阻和第二电阻的阻值使得所述第一电位控制点的电压大于所述三极管的导通阈值，所述第一三极管导通；
在所述输入电压小于预设电压范围的最小值时，串联的所述第四电阻和第五电阻的阻值使得所述第二电位控制点的电压小于所述三极管的导通阈值，所述第二三极管断开。
一种机顶盒，包括电压输入端、直流-直流DC-DC电源供电电路和本实施例所提供的过欠压保护电路，该过欠压保护电路连接在电压输入端和DC-DC电源供电电路之间。
本公开通过电压判断模块获取电压输入端输入的电压范围是否在DC-DC电源供电电路的预设电压范围中，并输出控制信号，控制模块与电压判断模块相连，根据控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通，即在电压输入端与DC-DC电源供电电路之间添加过欠压保护电路替代了相关技术中电压输入端与DC-DC电源供电电路直接相连，解决了在输入电压过高或过低时，DC-DC电源供电电路受损的问题，实现了在输入电压过高或过低时保护DC-DC电源供电电路。
附图说明
图1是本实施例中的过欠压保护电路的结构图；
图2是本实施例中的过欠压保护电路电压判断模块的结构图；
图3A是本实施例中的过欠压保护电路控制模块的结构图；
图3B是本实施例中的另一种过欠压保护电路的结构图；
图4是本实施例提供的机顶盒的结构示意图。
具体实施方式
下面结合附图和实施例对本公开进行说明。
图1为本实施例提供的过欠压保护电路的结构图，本实施例可适用于当输入电压过高或过低时，保护电源供电电路不被损坏的情况，该电路可集成于具有电源供电电路的设备中，尤为适用于机顶盒中。该过欠压保护电路的输出端与电源供电电路相连，本实施例提供的过欠压保护电路包括电压判断模块110和控制模块120。
电压判断模块110，设置为与电压输入端相连，用于检测输入电压范围，并根据输入电压范围输出控制信号；控制模块120，设置为第一端与电压判断模块110的输出端相连，第二端与电压输入端相连，第三端与DC-DC电源供电电路相连，用于根据电压判断模块110的控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通。
本实施例中，当电压输入端与DC-DC电源供电电路直接相连时，如果输入电压过高或过低，会导致DC-DC电源供电电路受损。电压判断模块110与电压输入端相连，检测输入电压是否在DC-DC电源供电电路的预设电压范围内，并根据检测结果输出控制信号。控制模块根据电压判断模块输出的控制信号控制DC-DC电源供电电路的工作状态。
示例性的，当输入电压小于DC-DC电源供电电路的预设电压范围的最小值时，控制模块根据控制信号控制DC-DC电源供电电路断开；当输入电压大于预设电压范围的最大值时，控制模块根据控制信号控制DC-DC电源供电电路断开；当输入电压在设电压范围内时，控制模块根据控制信号控制DC-DC电源供电电路导通，保证了当输入电压过高或过低时DC-DC电源供电电路断开，避免了在输入电压过高或过低时，DC-DC电源供电电路受损的问题。
本实施例通过电压判断模块获取电压输入端输入的电压，判断输入的电压是否在DC-DC电源供电电路的预设电压范围中，并输出控制信号，控制模块与电压判断模块相连，根据控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通，即在电压输入端与DC-DC电源供电电路之间添加过欠压保护电路替代了相关技术中电压输入端与DC-DC电源供电电路直接相连，解决了在输入电压过高或过低时，DC-DC电源供电电路受损的问题，实现了在输入电压过高或过低时保护DC-DC电源供电电路。
图2是本实施例提供的过欠压保护电路电压判断模块的结构图，本实施例是对上述实施例中的电压判断模块110工作原理和过程进行的阐述。电压判断模块110包括第一电阻R1、第二电阻R2、第三电阻R3、第四电阻R4、第五电阻R5、第六电阻R6、第一三极管Q1和第二三极管Q2。
第一电阻R1和第二电阻R2，串联在电压输入端和低电位点之间，第一电阻R1和第二电阻R2之间形成有第一电位控制点A。
第四电阻R4和第五电阻R5，串联在电压输入端和低电位点之间，第四电阻R4和第五电阻R5之间形成有第二电位控制点B。
第一三极管Q1的基极通过第三电阻R3与第一电位控制点A相连，第一三极管Q1的集电极和发射极串联在第二电位控制点B和低电位点之间，用于根据 第一电位控制点A的电压控制第一三极管Q1的导通和断开。
第二三极管Q2的基极通过第六电阻R6与第一三极管Q1的集电极相连，用于通过第二电位控制点B的电压控制第二三极管Q2的导通和断开，第二三极管Q2的集电极与控制模块120的第一端相连。
可选的，在输入电压小于预设电压范围的最小值时，串联的第一电阻R1和第二电阻R2的阻值使得第一电位控制点A的电压小于三极管的导通阈值，第一三极管Q1断开；在输入电压大于预设电压范围的最大值时，串联的第一电阻R1和第二电阻R2的阻值使得第一电位控制点A的电压大于三极管的导通阈值，第一三极管Q1导通。
在输入电压小于预设电压范围的最小值时，串联的第四电阻R4和第五电阻R5的阻值使得第二电位控制点B的电压小于三极管的导通阈值，第二三极管Q2断开。
本实施例中，串联的第一电阻R1和第二电阻R2对输入电压进行分压，第一电位控制点A的电压即第二电阻R2的电压，当输入电压小于预设电压范围的最小值时，第一电位控制点A的电压小于三极管的导通阈值，第一三极管Q1断开，串联的第四电阻R4和第五电阻R5对输入电压进行分压，第二电位控制点B的电压即第五电阻R5的电压，第二电位控制点B的电压小于三极管的导通阈值，第二三极管Q2断开，则电压判断模块110输出控制信号为高电平；当输入电压大于预设电压范围的最大值时，第一电位控制点A的电压即第二电阻R2的电压大于三极管的导通阈值，第一三极管Q1导通，第二电位控制点B的电压为0，小于三极管的导通阈值，第二三极管Q2断开，则电压判断模块110输出控制信号为高电平；当输入电压在预设电压范围内时，第一电位控制点A的电压即第二电阻R2的电压小于三极管的导通阈值，第一三极管Q1断开，第 二电位控制点B的电压即第五电阻R5的电压大于三极管的导通阈值，第二三极管Q2导通，则电压判断模块110输出控制信号为低电平。
本实施例通过第一电位控制点的电压值与第二电位控制点的电压值分别控制第一三极管与第二三极管的导通和断开以及控制电压判断模块的输出控制信号，即在输入电压是正常电压范围与非正常电压范围时控制输出的控制信号不同，控制电压输入端与DC-DC电源供电电路之间的断开与导通，解决了在输入电压过高或过低时，DC-DC电源供电电路受损的问题，实现了在输入电压过高或过低时保护DC-DC电源供电电路。
图3A是本实施例提供的过欠压保护电路控制模块的结构图，在上述实施例的基础上，本实施例是对控制模块120的工作原理和过程进行的阐述，控制模块120包括金属氧化物半导体(Metal Oxide Semiconductor，MOS)管Q3、第七电阻R7和第八电阻R8。
其中，MOS管Q3的栅极通过第八电阻R8与电压判断模块110的输出端相连，通过第七电阻R7与电压输入端相连，MOS管Q3的源极与电压输入端相连，MOS管Q3的漏极与DC-DC电源供电电路相连，MOS管Q3用于根据电压输入端的输入电压与电压判断模块110的控制信号控制MOS管Q3的工作状态。
本实施例中，当输入电压小于预设电压范围的最小值时，电压输入端输入电压为高电平，电压判断模块输出控制信号为高电平，MOS管Q3的栅极电压为高电平，则MOS管Q3断开；当输入电压大于预设电压范围的最大值时，电压输入端输入电压为高电平，电压判断模块输出控制信号为高电平，MOS管Q3的栅极电压为高电平，则MOS管Q3断开；当输入电压处于预设电压范围内时，电压判断模块输出控制信号为低电平，电压输入端输入电压为高电平，MOS管Q3的栅极电压为低电平，则MOS管Q3导通。即当输入电压在预设电压范围内 时，DC-DC电源供电电路与电压输入端导通，DC-DC电源供电电路处于工作状态，当输入电压在预设电压范围之外时，DC-DC电源供电电路与电压输入端断开，DC-DC电源供电电路处于停止工作状态，避免了输入电压过高或过低时，DC-DC电源供电电路受损的情况。
如图3B所示，图3B是本实施例提供的另一种过欠压保护电路的结构图，可以取DC-DC电源供电电路的正常工作电压为12V，预设电压范围为9V～13.8V，对此情况进行阐述。以下参数取值只是一种示例性取值，还可以存在其他取值，数值不同，过欠压电路中的每个电阻的阻值不同，可以根据情况进行相关调整。
串联的第一电阻R1和第二电阻R2对输入电压进行分压，当输入电压在0～13.8V的范围内，第一电位控制点A的电压即第二电阻R2的电压小于三极管的导通阈值(例如可以是0.6V)，示例性的，第一电阻R1和第二电阻R2的阻值可以是22KΩ和1KΩ。
串联的第四电阻R4和第五电阻R5对输入电压进行分压，当输入电压在0～9V的范围内，第二电位控制点B的电压即第五电阻R5的电压小于三极管的导通阈值，示例性的，第四电阻R4和第五电阻R5的阻值可以是14KΩ和1KΩ。
第三电阻R3和第六电阻R6用于限流，避免电流过高时损坏三极管，示例性的，第三电阻R3和第六电阻R6均可取值为10KΩ。
串联的第七电阻R7和第八电阻R8用于分压，示例性的，第七电阻R7和第八电阻R8分别可以取值为1KΩ和2KΩ。
本实施例通过控制模块根据电压判断模块输出控制信号控制MOS管的导通与断开，当输入电压在预设电压范围时，DC-DC电源供电电路与电压输入端导通，解决了在输入电压过高或过低时，DC-DC电源供电电路受损的问题，实现了在输入电压过高或过低时保护DC-DC电源供电电路。
在上述实施例的基础上，该过欠压保护电路还包括发光二极管(light-emitting diode，LED)灯。
LED灯与电压判断模块的输出端相连，用于根据电压判断模块的控制信号控制LED灯的工作状态。
当输入电压处于非正常电压范围时，电压判断模块输出端电压大于0，LED灯通电亮灯，当输入电压处于正常电压范围内时，电压判断模块输出端电压等于0，LED灯不亮。
本实施例中，用户可根据LED灯的工作情况获取当前的输入电压是否处于正常状态，并根据LED灯显示进行相应的处理。
图4是本实施例提供的一种机顶盒的结构示意图，该机顶盒400包括电压输入端410、DC-DC电源供电电路430和本实施例提供的任一过欠压保护电路420，过欠压保护电路420连接在电压输入端410和DC-DC电源供电电路430之间。
本实施例通过在电压输入端与DC-DC电源供电电路之间添加过欠压保护电路替代了相关技术中电压输入端与DC-DC电源供电电路直接相连，解决了在输入电压过高或过低时，DC-DC电源供电电路受损导致机顶盒不能开机的问题，可以在输入电压过高或过低时保护DC-DC电源供电电路，保证机顶盒正常运行。
工业实用性
本公开提供的过欠压保护电路和机顶盒，解决了在输入电压过高或过低时，DC-DC电源供电电路受损导致机顶盒不能开机的问题，在输入电压过高或过低时保护DC-DC电源供电电路，保证机顶盒的正常运行。

Claims (6)

  1. 一种过欠压保护电路，包括：
    电压判断模块，设置为与电压输入端相连，用于检测输入电压范围，并根据所述输入电压范围输出控制信号；
    控制模块，第一端与所述电压判断模块的输出端相连，第二端设置为与所述电压输入端相连，第三端设置为与直流-直流DC-DC电源供电电路相连，所述控制模块设置为：根据所述电压判断模块的控制信号控制电压输入端与DC-DC电源供电电路之间的断开与导通。
  2. 根据权利要求1所述的电路，其中，所述电压判断模块包括：
    第一电阻和第二电阻，串联在所述电压输入端和低电位点之间，所述第一电阻和第二电阻之间形成有第一电位控制点；
    第四电阻和第五电阻，串联在所述电压输入端和低电位点之间，所述第四电阻和第五电阻之间形成有第二电位控制点；
    第一三极管，所述第一三极管的基极通过第三电阻与所述第一电位控制点相连，所述第一三极管的集电极和发射极串联在第二电位控制点和低电位点之间，所述第一三极管设置为根据所述第一电位控制点的电压控制所述第一三极管的导通和断开；
    第二三极管，所述第二三极管的基极通过第六电阻与所述第一三极管的集电极相连，所述第二三极管的集电极与所述控制模块的第一端相连，所述第二三极管设置为通过所述第二电位控制点的电压控制所述第二三极管的导通和断开。
  3. 根据权利要求1所述的电路，其中，所述控制模块包括：
    金属氧化物半导体MOS管，所述MOS管的栅极通过第七电阻与所述电压输入端相连，通过第八电阻与所述电压判断模块的输出端相连，所述MOS管的 源极与所述电压输入端相连，所述MOS管的漏极与所述DC-DC电源供电电路相连，所述MOS管设置为根据所述电压输入端的输入电压与所述电压判断模块的控制信号控制所述MOS管的工作状态。
  4. 根据权利要求1-3任一项所述的电路，还包括：
    发光二极管LED灯，所述LED灯与所述电压判断模块的输出端相连，设置为根据所述电压判断模块的控制信号控制所述LED灯的工作状态。
  5. 根据权利要求2所述的电路，其中，在所述输入电压小于预设电压范围的最小值时，串联的所述第一电阻和第二电阻的阻值使得所述第一电位控制点的电压小于三极管的导通阈值，所述第一三极管断开；在所述输入电压大于预设电压范围的最大值时，串联的所述第一电阻和第二电阻的阻值使得所述第一电位控制点的电压大于所述三极管的导通阈值，所述第一三极管导通；
    在所述输入电压小于预设电压范围的最小值时，串联的所述第四电阻和第五电阻的阻值使得所述第二电位控制点的电压小于所述三极管的导通阈值，所述第二三极管断开。
  6. 一种机顶盒，包括电压输入端、直流-直流DC-DC电源供电电路，和权利要求1-5任一所述的过欠压保护电路，所述过欠压保护电路连接在电压输入端和DC-DC电源供电电路之间。
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