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WO2015090186A1 - 过压过流保护电路及电子装置 - Google Patents

过压过流保护电路及电子装置 Download PDF

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Publication number
WO2015090186A1
WO2015090186A1 PCT/CN2014/093960 CN2014093960W WO2015090186A1 WO 2015090186 A1 WO2015090186 A1 WO 2015090186A1 CN 2014093960 W CN2014093960 W CN 2014093960W WO 2015090186 A1 WO2015090186 A1 WO 2015090186A1
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WO
WIPO (PCT)
Prior art keywords
voltage
reference voltage
overvoltage
resistor
led
Prior art date
Application number
PCT/CN2014/093960
Other languages
English (en)
French (fr)
Inventor
张华�
张先明
Original Assignee
深圳市华星光电技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 深圳市华星光电技术有限公司 filed Critical 深圳市华星光电技术有限公司
Priority to US14/647,110 priority Critical patent/US9504117B2/en
Publication of WO2015090186A1 publication Critical patent/WO2015090186A1/zh

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]
    • H05B45/38—Switched mode power supply [SMPS] using boost topology
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/20—Responsive to malfunctions or to light source life; for protection
    • H05B47/24—Circuit arrangements for protecting against overvoltage
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
    • H05B47/20—Responsive to malfunctions or to light source life; for protection
    • H05B47/25—Circuit arrangements for protecting against overcurrent
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

  • the present invention relates to a protection circuit, and more particularly to an overvoltage and overcurrent protection circuit and an electronic device having an overvoltage and overcurrent protection circuit.
  • LEDs are used as electronic devices for backlight modules, such as televisions and computer displays.
  • the characteristics of the LED will change, that is, the voltage required for the LED to illuminate slowly rises with the increase of time, thereby driving the output voltage of the backlight driving circuit of the LED. It will also gradually increase.
  • the OVP (Output Over Voltage Protection) value and the OCP (Input Over Current Protection) value are preset and difficult to change, so that when the output voltage of the backlight driving circuit gradually rises, the OVP value and the OCP value are relatively It will be low, and it is easy for the LED to work normally but the protection function is triggered abnormally.
  • the invention provides an overcurrent and overvoltage protection circuit and an electronic device, which can increase the threshold of the trigger overvoltage and overcurrent protection as the time of operation of the electronic device increases.
  • An overvoltage and overcurrent protection circuit for overcurrent and overvoltage protection of an LED module powered by a power supply the LED module includes a positive input end, and the power supply includes an output end, wherein the The over-current protection circuit comprises: an over-voltage detection unit connected between the positive input end of the LED module and the ground for detecting the voltage of the positive input terminal of the LED module to generate a voltage with the positive input terminal V a proportional overvoltage detection voltage; an overcurrent detection unit electrically connected between the output end of the power supply and the ground for detecting an input current of the LED module to generate an overcurrent proportional to the input current Detecting a voltage; the LED driving unit is connected to the overvoltage detecting unit and the overcurrent detecting unit, and configured to respectively convert a reference voltage into an overvoltage reference voltage and an overcurrent reference voltage proportional to the reference voltage, The LED driving unit compares the overvoltage reference voltage and the overcurrent reference voltage with the overvoltage detection voltage and the overcurrent detection voltage respectively, and determines whether overcurrent or overvoltage protection
  • the LED driving unit includes an overvoltage detecting end, an overcurrent detecting end and a reference voltage input end; the overvoltage detecting end is configured to acquire the overvoltage detecting voltage, and the overcurrent detecting end is used for the overcurrent detecting end Obtaining the overcurrent detection voltage, the reference voltage input end is used for accessing a reference voltage; the reference voltage adjustment unit includes a voltage input end, a voltage output end, and a controlled end; the voltage input end and a voltage end end Connected, the voltage output terminal is connected to the reference voltage input end of the LED driving unit to output the reference voltage to the reference voltage input end of the LED driving unit; the control unit includes a control end, the control end of the control unit and the reference The controlled end of the voltage adjustment unit is connected.
  • the control unit acquires an initial value of the working voltage in the LED characteristic curve data when the LED module starts working, and obtains a voltage corresponding to the time in the LED characteristic curve data according to the working time of the LED module in real time,
  • the control unit outputs a boost control signal to the controlled end of the reference voltage adjusting unit through the control terminal when comparing the voltage corresponding to the current time with the initial value of the working voltage to be greater than a predetermined value.
  • the reference voltage adjustment unit increases the reference voltage output by the voltage output terminal.
  • the overvoltage detecting unit includes a first resistor and a second resistor connected in series between the positive input terminal of the LED module and the ground, and the voltage on the connection node of the first resistor and the second resistor is Pressing the detection voltage, the overvoltage detection end of the LED driving unit is connected to the connection node to obtain the overvoltage detection voltage; the overcurrent detection unit includes an electrical connection between the output end of the power supply and the ground.
  • the third resistor, the voltage at the remote end of the third resistor is the overcurrent detection voltage, and the overcurrent detection voltage is proportional to the current flowing through the third resistor.
  • the reference voltage adjustment unit includes a first NMOS transistor, a second NMOS transistor, and a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor.
  • the fourth resistor and the fifth resistor are connected in series to the voltage input terminal and the ground.
  • the connection node of the fourth resistor and the fifth resistor constitutes the voltage output terminal; the source of the first NMOS transistor is grounded through a sixth resistor, and the drain is connected to the fourth resistor and the fifth resistor; the second The gate of the NMOS transistor forms the controlled end, the source of the second NMOS transistor is grounded, the drain is connected to the gate of the first NMOS transistor, and is also connected to the voltage input terminal through the seventh resistor.
  • the LED module further includes at least one LED string connected in parallel between the positive input terminal and the ground.
  • Each LED string includes a plurality of LED lamps connected in series between the positive input and ground.
  • the LED characteristic curve data is determined according to the characteristics of the LED string included in the LED module.
  • An electronic device includes a power supply, an LED module, and an overcurrent and overvoltage protection circuit, wherein the power supply is used to supply power to the LED module, the LED module includes a positive input terminal, and the power supply includes an output end, wherein the overvoltage
  • the overcurrent protection circuit comprises: an overvoltage detection unit connected between the positive input end of the LED module and the ground for detecting the voltage of the positive input terminal of the LED module to generate a voltage with the positive input terminal V a proportional overvoltage detection voltage; an overcurrent detection unit electrically connected between the output end of the power supply and the ground for detecting an input current of the LED module to generate an overcurrent detection proportional to the input current Measuring voltage;
  • the LED driving unit is connected to the overvoltage detecting unit and the overcurrent detecting unit, and configured to respectively convert a reference voltage into an overvoltage reference voltage and an overcurrent reference voltage proportional to the reference voltage, the LED The driving unit compares the overvoltage reference voltage and the overcurrent reference voltage with the overvoltage detection voltage and
  • the LED driving unit includes an overvoltage detecting end, an overcurrent detecting end and a reference voltage input end; the overvoltage detecting end is configured to acquire the overvoltage detecting voltage, and the overcurrent detecting end is used for the overcurrent detecting end Obtaining the overcurrent detection voltage, the reference voltage input end is used for accessing a reference voltage; the reference voltage adjustment unit includes a voltage input end, a voltage output end, and a controlled end; the voltage input end and a voltage end end Connected, the voltage output terminal is connected to the reference voltage input end of the LED driving unit to output the reference voltage to the reference voltage input end of the LED driving unit; the control unit includes a control end, the control end of the control unit and the reference The controlled end of the voltage adjustment unit is connected.
  • the control unit acquires an initial value of the working voltage in the LED characteristic curve data when the LED module starts working, and obtains a voltage corresponding to the time in the LED characteristic curve data according to the working time of the LED module in real time,
  • the control unit outputs a boost control signal to the controlled end of the reference voltage adjusting unit through the control terminal when comparing the voltage corresponding to the current time with the initial value of the working voltage to be greater than a predetermined value.
  • the reference voltage adjustment unit increases the parameter output by the voltage output terminal Test voltage.
  • the overvoltage detecting unit includes a first resistor and a second resistor connected in series between the positive input terminal of the LED module and the ground, and the voltage on the connection node of the first resistor and the second resistor is Pressing the detection voltage, the overvoltage detection end of the LED driving unit is connected to the connection node to obtain the overvoltage detection voltage; the overcurrent detection unit includes an electrical connection between the output end of the power supply and the ground.
  • the third resistor, the voltage at the remote end of the third resistor is the overcurrent detection voltage, and the overcurrent detection voltage is proportional to the current flowing through the third resistor.
  • the reference voltage adjustment unit includes a first NMOS transistor, a second NMOS transistor, and a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor.
  • the fourth resistor and the fifth resistor are connected in series to the voltage input terminal and the ground.
  • the connection node of the fourth resistor and the fifth resistor constitutes the voltage output terminal; the source of the first NMOS transistor is grounded through a sixth resistor, and the drain is connected to the fourth resistor and the fifth resistor; the second The gate of the NMOS transistor forms the controlled end, the source of the second NMOS transistor is grounded, the drain is connected to the gate of the first NMOS transistor, and is also connected to the voltage input terminal through the seventh resistor.
  • the LED module further includes at least one LED string connected in parallel between the positive input terminal and the ground, and each LED string includes a plurality of LED lamps connected in series between the positive input terminal and the ground.
  • the LED characteristic curve data is determined in advance according to the characteristics of the LED string included in the LED module.
  • the electronic device is one of a liquid crystal television, a display, a mobile phone, a tablet computer, and a notebook computer.
  • the overcurrent and overvoltage protection circuit and the electronic device of the invention can increase the threshold of the trigger overvoltage and overcurrent protection as the time of operation of the electronic device increases, and avoid abnormally triggering overcurrent or overvoltage protection.
  • FIG. 1 is a block diagram of an electronic device having an overvoltage and overcurrent protection circuit according to an embodiment of the present invention.
  • FIG. 2 is a schematic diagram of LED characteristic curve data in an embodiment of the present invention.
  • FIG. 3 is a detailed circuit diagram of an electronic device having an overvoltage and overcurrent protection circuit according to an embodiment of the present invention.
  • FIG. 1 is a block diagram of the electronic device 100 with the overvoltage and overcurrent protection circuit 1 of the present invention.
  • the electronic device 100 includes a power source 10, an LED module 20, and an overvoltage and overcurrent protection circuit 30.
  • the LED module 20 includes a positive input terminal V+ and a plurality of LED strings 201 connected in parallel between the positive input terminal V+ and the ground.
  • Each LED string 201 includes a plurality of LEDs connected in series between the positive input terminal V+ and the ground. Light D.
  • the power supply 10 includes an output terminal Vin, and an output terminal Vin of the power supply 10 is electrically connected to the positive input terminal 201 of the LED module 20 for supplying power to the LED module 20 and the control unit 31.
  • the power source 10 can be a battery or a power adapter or the like.
  • the overvoltage and overcurrent protection circuit 30 includes an overvoltage detection unit 31, an overcurrent detection unit 32, an LED drive unit 33, a reference voltage adjustment unit 34, and a control unit 35.
  • the overvoltage detecting unit 31 is connected between the positive input terminal V+ of the LED module 20 and the ground for detecting the voltage of the positive input terminal V+ of the LED module 20 to generate a voltage with the positive input terminal V+. Proportional overvoltage detection voltage.
  • the overcurrent detecting unit 32 is electrically connected to the output terminal Vin of the power source 10 and the ground for detecting the input current of the LED module 20 to generate an overcurrent detecting voltage proportional to the input current.
  • the LED driving unit 33 is connected to the overvoltage detecting unit 31 and the overcurrent detecting unit 33 for converting a reference voltage Vref into an overvoltage reference voltage and an overcurrent reference voltage which are proportional to the reference voltage, respectively.
  • the LED driving unit 33 compares the overvoltage reference voltage and the overcurrent reference voltage with the overvoltage detection voltage and the overcurrent detection voltage, respectively, to determine whether overcurrent or overvoltage protection is performed.
  • the reference voltage adjustment unit 34 is configured to output the reference voltage Vref to the LED driving unit 33.
  • the control unit 35 stores an LED characteristic curve data LD, which reflects the relationship between the operating voltage required by the LED module 20 and the time.
  • the control unit 35 according to the LED characteristics.
  • the curve data LD determines that the variation range of the operating voltage of the LED module 20 exceeds a predetermined value
  • the reference voltage adjustment unit 34 is controlled to increase the output reference voltage Vref.
  • the LED characteristic curve data LD is determined according to the characteristics of the LED string 201 included in the LED module 20, that is, according to the change relationship of the operating voltage of the LED string 201 included in the LED module 20 with time, and It is stored in the control unit 35 by means of burning or the like.
  • the LED driving unit 33 includes an overvoltage detecting terminal Vsen, an overcurrent detecting terminal Isen, and a reference voltage input terminal 331.
  • the overvoltage detection terminal Vsen is used to acquire the overvoltage detection voltage
  • the overcurrent detection terminal Isen is used to acquire the overcurrent detection voltage.
  • the reference voltage input terminal 331 is used to access the reference voltage Vref.
  • the LED driving unit 33 is configured to separately convert the reference voltage connected to the reference voltage input terminal 331 Forming an overvoltage reference voltage proportional to the reference voltage Vref and an overcurrent reference voltage, the LED driving unit 33 and the overvoltage reference voltage and the overcurrent reference voltage respectively corresponding to the overvoltage detection voltage and the overcurrent detection voltage Compare and decide whether to overcurrent or overvoltage protection.
  • the LED driving unit 33 performs over-current protection when the over-voltage detection voltage is greater than the over-voltage reference voltage, and performs over-current protection when the over-current detection voltage is greater than the over-current reference voltage.
  • the reference voltage adjustment unit 34 includes a voltage input terminal 341, a voltage output terminal 342, and a controlled terminal 343.
  • the voltage input terminal 341 is connected to a voltage terminal V0.
  • the voltage output terminal 342 is connected to the reference voltage input terminal 331 of the LED driving unit 33 to output the reference voltage Vref to the reference voltage input terminal 331 of the LED driving unit 33.
  • the control unit 35 includes a control terminal 351.
  • the control terminal 351 of the control unit 35 is connected to the controlled terminal 343 of the reference voltage adjustment unit 34.
  • the control unit 35 determines the operation of the LED module 20 according to the LED characteristic curve data LD.
  • a boost control signal is outputted through the control terminal 351 to the controlled terminal 343 of the reference voltage adjusting unit 34.
  • the reference voltage adjusting unit 34 controls to increase the reference voltage Vref output by the voltage output terminal 342 when the controlled terminal 341 receives the boosting control signal.
  • the overvoltage reference voltage and the overcurrent reference voltage are correspondingly increased, so that the threshold for overcurrent or overvoltage protection is increased, so that when the operating voltage of the LED module 20 rises normally, the abnormality is not triggered. Flow or overvoltage protection.
  • the control unit 35 obtains an initial value of the working voltage in the LED characteristic curve data LD when the LED module 20 starts to work, and obtains the time in the LED characteristic curve data LD according to the working time of the LED module 20 in real time. Corresponding voltage, the control unit 35 outputs a boost control signal to the reference voltage adjusting unit through the control terminal 351 when comparing the voltage corresponding to the current time with the initial value of the operating voltage by a predetermined value. Controlled end 343 of 34.
  • the electronic device 100 further includes a switch unit 40 and a diode D1.
  • the switch unit 40 is electrically connected between the output terminal Vin of the power source 10 and the overcurrent detecting unit 31.
  • the LED driving unit further includes a control terminal 332, and the control terminal 332 is connected to the switch unit 40.
  • the LED driving unit outputs a PWM (Pulse-Width Modulation) signal to the switch unit 40 through the control terminal 332.
  • the switching unit 40 is controlled to be alternately turned on and off, so that the voltage output from the output terminal Vin of the power source 10 is converted into a switching power supply voltage to supply power to the LED module 20.
  • the anode of the diode D1 is connected to the switch unit 40 and the output terminal Vin of the power source 10, and the cathode Connected to the positive input terminal V+ of the LED module 20, the diode D1 is used to uni-directionally pass the voltage of the LED module 20 from the output terminal of the power source 10 to avoid reverse voltage.
  • the LED driving unit 33 is an LED constant current driving chip, and the voltage terminal V0 is connected to the power source 10 and is at a high level.
  • the overvoltage detecting unit 31 includes resistors R1 and R2 connected in series between the positive input terminal V+ of the LED module 20 and the ground.
  • the voltage across the connection node N1 of the resistors R1 and R2 is the overvoltage detection voltage.
  • the overvoltage detection terminal Vsen of the LED driving unit 33 is connected to the connection node N1 to obtain the overvoltage detection voltage.
  • the overvoltage detection voltage is equal to the voltage of the positive input terminal V+ of the LED module 20. Just proportional.
  • the overcurrent detecting unit 32 includes a resistor R3 electrically connected to the output terminal Vin of the power source 10 and the ground, and the voltage on the remote terminal N2 of the resistor R3 is the overcurrent detecting voltage, and the overcurrent The detection voltage is proportional to the current flowing through the resistor R3.
  • the reference voltage adjusting unit 34 includes an NMOS transistor Q1, an NMOS transistor Q2, and resistors R4, R5, R6, and R7.
  • the resistors R4 and R5 are connected in series between the voltage input terminal 341 and the ground.
  • the connection node of the resistors R4 and R5 constitutes the voltage output terminal 342.
  • the source of the NMOS transistor Q1 is grounded via a resistor R6, and the drain is connected to a connection node of the resistors R4 and R5, that is, the voltage output terminal 342. Therefore, the NMOS transistor Q1 is connected in series with the resistor R6 and is connected in parallel with the resistor R5 between the voltage output terminal 342 and the ground.
  • the gate of the NMOS transistor Q2 constitutes the controlled terminal 343.
  • the source of the NMOS transistor Q2 is grounded, the drain is connected to the gate of the NMOS transistor Q1, and is also connected to the voltage input terminal 341 through the resistor R7.
  • the boost control signal is a high level signal.
  • the control unit 35 determines that the operating voltage change of the LED module 20 exceeds the predetermined value according to the LED characteristic curve data LD, the control unit 35 outputs a high-level boosting control signal through the control terminal 351.
  • the gate of the NMOS transistor Q2 receives the boost control signal of the high level to turn on the NMOS transistor Q2, so that the gate of the NMOS transistor Q1 is grounded through the turned-on NMOS transistor Q2.
  • the NMOS transistor Q1 is turned off correspondingly, and the path of the current of the resistor R6 is cut off.
  • the reference voltage Vref V0 * R5 / (R4 + R5).
  • the reference voltage Vref is greater than the reference voltage Vref when the LED module 20 is initially operated. That is, the reference voltage Vref is increased, so that the overvoltage reference voltage and the overcurrent reference voltage are also correspondingly increased, so that the threshold of overcurrent or overvoltage protection is increased as the operating voltage of the LED module 20 rises normally. Increase, does not abnormally trigger overcurrent or overvoltage protection.
  • the switch unit 40 is an NMOS transistor Q3.
  • the gate of the NMOS transistor Q3 is connected to the control terminal 332 of the LED driving unit 33.
  • the source is connected to the remote terminal N2 of the resistor R3, and the drain and the power source 10 are connected.
  • the output Vin is connected.
  • the LED driving unit 33 outputs the PWM signal through the control terminal 332 to control the NMOS transistor Q3 to be alternately turned on and off, thereby converting the power supply voltage outputted from the output terminal Vin of the power supply 10 into a voltage in the form of a switching power supply. 20 power supply.
  • the diode D1 is forwardly connected between the drain of the NMOS transistor Q3 and the positive voltage terminal V+ of the LED module 20.
  • Each LED string 201 of the LED module 20 further includes a resistor R connected in series between the LED lamp D and the ground.
  • the NMOS transistors Q1, Q2, and Q3 may be replaced by an NPN transistor or a PMOS transistor or a PNP transistor.
  • the electronic device 100 can be a liquid crystal television, a display, a mobile phone, a tablet computer, a notebook computer, or the like.
  • the electronic device 100 further includes an inductor L1 and a capacitor C1, which are not described herein because they are not related to the improvement of the present invention.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Led Devices (AREA)
  • Dc-Dc Converters (AREA)

Abstract

一种过压过流保护电路（30），包括用于产生过压侦测电压的过压侦测单元（31）、用于产生过流侦测电压的过流侦测单元（32）、用于将参考电压分别转换成与过压参考电压以及过流参考电压并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较的LED驱动单元（33）、用于输出该参考电压至该LED驱动单元（33）的参考电压调整单元（34）以及一控制单元（35）。该控制单元（35）根据一LED特性曲线数据判断LED模组（20）的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元（34）增大所输出的参考电压。本发明还提供一种电子装置（1），本发明能够随着电子装置（1）的工作时间的增加而增大过流过压保护的阈值。

Description

过压过流保护电路及电子装置 技术领域
本发明涉及一种保护电路，特别涉及一种过压过流保护电路及具有过压过流保护电路的电子装置。
背景技术
目前使用LED(发光二极管，light-emitting diode)作为背光模组的电子装置，例如电视机、电脑显示屏越来越多。一般情况下，在电子装置长时间工作后，LED的特性会改变，即LED点亮所需的电压会随时间的增加而缓慢呈曲线上升，从而，驱动该LED发光的背光驱动电路的输出电压也会逐渐上升。目前，对于OVP(输出过电压保护)值、OCP(输入过电流保护)值均为预先设置，且难以更改，从而，当背光驱动电路的输出电压逐渐上升时，该OVP值以及OCP值相对就会偏低，容易出现LED工作正常却异常触发保护功能的情况。
发明内容
本发明提供一种过流过压保护电路及电子装置，能够随着电子装置工作的时间的增加而增大触发过压及过流保护的阈值。
一种过压过流保护电路，用于对一电子装置的通过电源供电的LED模组进行过流和过压保护，该LED模组包括正极输入端，该电源包括输出端，其中，该过压过流保护电路包括：过压侦测单元，连接于该LED模组的正极输入端以及地之间，用于侦测LED模组的正极输入端的电压而产生一与正极输入端V的电压成比例的过压侦测电压；过流侦测单元，电连接于该电源的输出端以及地之间，用于侦测LED模组的输入电流而产生一与该输入电流成正比的过流侦测电压；LED驱动单元，与该过压侦测单元以及过流侦测单元连接，用于将一参考电压分别转换成与该参考电压成正比的过压参考电压以及过流参考电压，该LED驱动单元并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护；参考电压调整单元，用于输出该参考电压至该LED驱动单元；以及控制单元，其中，该控制单元存储有一LED特性曲线 数据，该LED特性曲线数据反映了LED模组所需的工作电压随时间的变化关系，该控制单元根据该LED特性曲线数据判断LED模组的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元增大所输出的参考电压。
其中，该LED驱动单元包括一过压侦测端、一过流侦测端以及一参考电压输入端；该过压侦测端用于获取该过压侦测电压，该过流侦测端用于获取该过流侦测电压，该参考电压输入端用于接入参考电压；该参考电压调整单元包括一电压输入端、一电压输出端以及一受控端；该电压输入端与一电压端连接，该电压输出端与该LED驱动单元的参考电压输入端连接而输出该参考电压至该LED驱动单元的参考电压输入端；该控制单元包括一控制端，该控制单元的控制端与该参考电压调整单元的受控端连接。
其中，该控制单元在LED模组开始工作时获取该LED特性曲线数据中的工作电压的初始值，并实时根据LED模组的工作时间而获得该LED特性曲线数据中的时间对应的电压，该控制单元并在比较当前时间对应的电压与该工作电压的初始值比较的变化幅度大于一预定值时，通过该控制端输出一升压控制信号至该参考电压调整单元的受控端，而控制参考电压调整单元增大该电压输出端所输出的参考电压。
其中，该过压侦测单元包括串联于该LED模组的正极输入端以及地之间的第一电阻以及第二电阻，该第一电阻以及第二电阻的连接节点上的电压即为该过压侦测电压，该LED驱动单元的过压侦测端与该连接节点连接而获得该过压侦测电压；该过流侦测单元包括一电连接于该电源的输出端以及地之间的第三电阻，该第三电阻的远地端上的电压即为该过流侦测电压，该过流侦测电压与流过该第三电阻上的电流成正比。
其中，该参考电压调整单元包括第一NMOS管、第二NMOS管以及第四电阻、第五电阻、第六电阻以及第七电阻；该第四电阻以及第五电阻串联于该电压输入端与地之间，该第四电阻以及第五电阻的连接节点构成该电压输出端；该第一NMOS管的源极通过第六电阻接地，漏极与该第四电阻以及第五电阻连接；该第二NMOS管的栅极构成该受控端，该第二NMOS管的源极接地，漏极与该第一NMOS管的栅极连接，同时还通过该第七电阻与电压输入端连接。
其中，该LED模组还包括至少一个并联于该正极输入端以及地之间的LED串， 每一LED串包括串联于该正极输入端以及地之间的多个LED灯。
其中，该LED特性曲线数据为预先根据该LED模组包括的LED串的特性制定得出。
一种电子装置，包括电源、LED模组以及过流过压保护电路，该电源用于为该LED模组供电，该LED模组包括正极输入端，该电源包括输出端，其中，该过压过流保护电路包括：过压侦测单元，连接于该LED模组的正极输入端以及地之间，用于侦测LED模组的正极输入端的电压而产生一与正极输入端V的电压成比例的过压侦测电压；过流侦测单元，电连接于该电源的输出端以及地之间，用于侦测LED模组的输入电流而产生一与该输入电流成正比的过流侦测电压；LED驱动单元，与该过压侦测单元以及过流侦测单元连接，用于将一参考电压分别转换成与该参考电压成正比的过压参考电压以及过流参考电压，该LED驱动单元并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护；参考电压调整单元，用于输出该参考电压至该LED驱动单元；以及控制单元，其中，该控制单元存储有一LED特性曲线数据，该LED特性曲线数据反映了LED模组所需的工作电压随时间的变化关系，该控制单元根据该LED特性曲线数据判断LED模组的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元增大所输出的参考电压。
其中，该LED驱动单元包括一过压侦测端、一过流侦测端以及一参考电压输入端；该过压侦测端用于获取该过压侦测电压，该过流侦测端用于获取该过流侦测电压，该参考电压输入端用于接入参考电压；该参考电压调整单元包括一电压输入端、一电压输出端以及一受控端；该电压输入端与一电压端连接，该电压输出端与该LED驱动单元的参考电压输入端连接而输出该参考电压至该LED驱动单元的参考电压输入端；该控制单元包括一控制端，该控制单元的控制端与该参考电压调整单元的受控端连接。
其中，该控制单元在LED模组开始工作时获取该LED特性曲线数据中的工作电压的初始值，并实时根据LED模组的工作时间而获得该LED特性曲线数据中的时间对应的电压，该控制单元并在比较当前时间对应的电压与该工作电压的初始值比较的变化幅度大于一预定值时，通过该控制端输出一升压控制信号至该参考电压调整单元的受控端，而控制参考电压调整单元增大该电压输出端所输出的参 考电压。
其中，该过压侦测单元包括串联于该LED模组的正极输入端以及地之间的第一电阻以及第二电阻，该第一电阻以及第二电阻的连接节点上的电压即为该过压侦测电压，该LED驱动单元的过压侦测端与该连接节点连接而获得该过压侦测电压；该过流侦测单元包括一电连接于该电源的输出端以及地之间的第三电阻，该第三电阻的远地端上的电压即为该过流侦测电压，该过流侦测电压与流过该第三电阻上的电流成正比。
其中，该参考电压调整单元包括第一NMOS管、第二NMOS管以及第四电阻、第五电阻、第六电阻以及第七电阻；该第四电阻以及第五电阻串联于该电压输入端与地之间，该第四电阻以及第五电阻的连接节点构成该电压输出端；该第一NMOS管的源极通过第六电阻接地，漏极与该第四电阻以及第五电阻连接；该第二NMOS管的栅极构成该受控端，该第二NMOS管的源极接地，漏极与该第一NMOS管的栅极连接，同时还通过该第七电阻与电压输入端连接。
其中，该LED模组还包括至少一个并联于该正极输入端以及地之间的LED串，每一LED串包括串联于该正极输入端以及地之间的多个LED灯。
该LED特性曲线数据为预先根据该LED模组包括的LED串的特性制定得出。
其中，该电子装置为液晶电视、显示器、手机、平板电脑以及笔记本电脑中的一种。
本发明的过流过压保护电路及电子装置，能够随着电子装置工作的时间的增加而增大触发过压及过流保护的阈值，避免异常触发过流或过压保护。
附图说明
图1是本发明一实施方式中具有过压过流保护电路的电子装置的模块架构图。
图2是本发明一实施方式中LED特性曲线数据的示意图。
图3是本发明一实施方式中具有过压过流保护电路的电子装置的具体电路图。
具体实施方式
请参阅图1，为本发明具有过压过流保护电路1的电子装置100的模块架构图。该电子装置100包括电源10、LED模组20以及过压过流保护电路30。
该LED模组20包括正极输入端V+以及多个并联于该正极输入端V+以及地之间的LED串201，每一LED串201包括串联于该正极输入端V+以及地之间的多个LED灯D。
该电源10包括输出端Vin，该电源10的输出端Vin与该LED模组20的正极输入端201电连接，该电源10用于为LED模组20以及控制单元31供电。其中，该电源10可为电池或电源适配器等。
该过压过流保护电路30包括一过压侦测单元31、一过流侦测单元32、一LED驱动单元33、一参考电压调整单元34以及一控制单元35。
该过压侦测单元31连接于该LED模组20的正极输入端V+以及地之间，用于侦测LED模组20的正极输入端V+的电压而产生一与正极输入端V+的电压成比例的过压侦测电压。
该过流侦测单元32电连接于该电源10的输出端Vin以及地之间，用于侦测LED模组20的输入电流而产生一与该输入电流成正比的过流侦测电压。
该LED驱动单元33与该过压侦测单元31以及过流侦测单元33连接，用于将一参考电压Vref分别转换成与该参考电压成正比的过压参考电压以及过流参考电压，该LED驱动单元33并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护。
该参考电压调整单元34用于输出该参考电压Vref至该LED驱动单元33。
请一并参阅图2，该控制单元35存储有一LED特性曲线数据LD，该LED特性曲线数据LD反映了LED模组20所需的工作电压随时间的变化关系，该控制单元35根据该LED特性曲线数据LD判断LED模组20的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元34增大所输出的参考电压Vref。其中，该LED特性曲线数据LD为预先根据该LED模组20包括的LED串201的特性制定得出，即根据该LED模组20包括的LED串201的工作电压随时间的变化关系制定，并通过烧录等方式存储于该控制单元35中。
具体的，该LED驱动单元33包括一过压侦测端Vsen、一过流侦测端Isen以及一参考电压输入端331。该过压侦测端Vsen用于获取该过压侦测电压，该过流侦测端Isen用于获取该过流侦测电压。该参考电压输入端331用于接入参考电压Vref。该LED驱动单元33用于将该参考电压输入端331接入的参考电压分别转换 成与该参考电压Vref成正比的过压参考电压以及过流参考电压，该LED驱动单元33并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护。具体的，该LED驱动单元33比较该过压侦测电压大于该过压参考电压时进行过压保护，以及比较该过流侦测电压大于过流参考电压时进行过流保护。
该参考电压调整单元34包括一电压输入端341、一电压输出端342以及一受控端343。该电压输入端341与一电压端V0连接，该电压输出端342与该LED驱动单元33的参考电压输入端331连接而输出该参考电压Vref至该LED驱动单元33的参考电压输入端331。
该控制单元35包括一控制端351，该控制单元35的控制端351与该参考电压调整单元34的受控端343连接，该控制单元35根据该LED特性曲线数据LD判断LED模组20的工作电压的变化幅度超过一预定值时，通过该控制端351输出一升压控制信号至该参考电压调整单元34的受控端343。该参考电压调整单元34在受控端341接收到该升压控制信号时，控制增大该电压输出端342输出的参考电压Vref。从而，该过压参考电压以及过流参考电压也相应增大，使得进行过流或过压保护的阈值增大，从而使得该LED模组20的工作电压正常升高时，不会异常触发过流或过压保护。
其中，该控制单元35在LED模组20开始工作时获取该LED特性曲线数据LD中的工作电压的初始值，并实时根据LED模组20的工作时间而获得该LED特性曲线数据LD中的时间对应的电压，该控制单元35并在比较当前时间对应的电压与该工作电压的初始值比较的变化幅度大于一预定值时，通过该控制端351输出一升压控制信号至该参考电压调整单元34的受控端343。
其中，该电子装置100还包括一开关单元40以及一二极管D1，该开关单元40电连接于该电源10的输出端Vin以及该过流侦测单元31之间。该LED驱动单元还包括一控制端332，该控制端332与该开关单元40连接，该LED驱动单元通过该控制端332输出PWM(Pulse-Width Modulation，脉宽调制)信号至该开关单元40而控制该开关单元40交替导通截止，从而将该电源10的输出端Vin输出的电压转换为开关电源电压而为该LED模组20供电。
该二极管D1的阳极与该开关单元40以及该电源10的输出端Vin连接，阴极 与该LED模组20的正极输入端V+连接，该二极管D1用于单向导通从电源10的输出端Vin值LED模组20的电压，避免反向电压。
其中，该LED驱动单元33为一LED恒流驱动芯片，该电压端V0为与该电源10连接而处于高电平。
请参考图3，具体的，该过压侦测单元31包括串联于该LED模组20的正极输入端V+以及地之间的电阻R1、R2。该电阻R1以及R2的连接节点N1上的电压即为该过压侦测电压。该LED驱动单元33的过压侦测端Vsen与该连接节点N1连接而获得该过压侦测电压，显然，该过压侦测电压与该该LED模组20的正极输入端V+的电压成正比。
该过流侦测单元32包括一电连接于该电源10的输出端Vin以及地之间的电阻R3，该电阻R3的远地端N2上的电压即为该过流侦测电压，该过流侦测电压与流过该电阻R3上的电流成正比。
该参考电压调整单元34包括NMOS管Q1、NMOS管Q2以及电阻R4、R5、R6、R7，该电阻R4以及R5串联于该电压输入端341与地之间。该电阻R4以及R5的连接节点构成该电压输出端342。该NMOS管Q1的源极通过电阻R6接地，漏极与该电阻R4以及R5的连接节点，即该电压输出端342连接。从而，该NMOS管Q1与电阻R6串联后与该电阻R5并联于该电压输出端342与地之间。该NMOS管Q2的栅极构成该受控端343，该NMOS管Q2的源极接地，漏极与该NMOS管Q1的栅极连接，同时还通过该电阻R7与电压输入端341连接。
在本实施方式中，该该升压控制信号为高电平信号。
当该LED模组20初始工作时，该控制单元35未输出该高电平的升压控制信号时，该NMOS管Q2截止，该NMOS管Q1的栅极通过该电阻R7与该电压端V0电连接而获得高电平，从而该NMOS管Q1导通。从而，电阻R6与R5并联后与该电阻R4串联于该电压输入端341与地之间。此时，该参考电压Vref＝V0*(R5//R6)/(R4+R5//R6)。
从而，当该控制单元35根据该LED特性曲线数据LD判断LED模组20的工作电压变化超过该预定值时，该控制单元35通过该控制端351输出高电平的升压控制信号。该NMOS管Q2的栅极接收该高电平的升压控制信号而使得该NMOS管Q2导通，从而，该NMOS管Q1的栅极通过该导通的NMOS管Q2接地而处 于低电平，该NMOS管Q1相应截止，该电阻R6所在电流之路被截断。从而，此时该参考电压Vref＝V0*R5/(R4+R5)。显然，由于电阻R5的电阻值大于电阻R5与电阻R6并联后的值，因此，此时，该参考电压Vref大于该LED模组20初始工作时的参考电压Vref。即，参考电压Vref增大，从而该过压参考电压以及过流参考电压也相应增大，从而，随着该LED模组20的工作电压正常升高，该进行过流或过压保护的阈值增大，不会异常触发过流或过压保护。
其中，该开关单元40为一NMOS管Q3，该NMOS管Q3的栅极与该LED驱动单元33的控制端332连接，源极与该电阻R3的远地端N2连接，漏极与该电源10的输出端Vin连接。该LED驱动单元33通过该控制端332输出该PWM信号控制该NMOS管Q3交替导通截止，从而将该电源10的输出端Vin输出的电源电压转化为开关电源形式的电压而为该LED模组20供电。
该二极管D1正向连接于该NMOS管Q3的漏极以及该LED模组20的正极电压端V+之间。其中，该LED模组20的每一LED串201还包括串联于LED灯D以及地之间的电阻R。
其中，该NMOS管Q1、Q2、Q3可为NPN三极管或PMOS管、PNP三极管代替。该电子装置100可为液晶电视、显示器、手机、平板电脑、笔记本电脑等。
其中，该电子装置100还包括电感L1以及电容C1，由于与本发明的改进无关，故不在此赘述。
以上具体实施方式对本发明进行了详细的说明，但这些并非构成对本发明的限制。本发明的保护范围并不以上述实施方式为限，但凡本领域普通技术人员根据本发明所揭示内容所作的等效修饰或变化，皆应纳入权利要求书中记载的保护范围内。

Claims (15)

  1. 一种过压过流保护电路，用于对一电子装置的通过一电源供电的LED模组进行过流和过压保护，该LED模组包括正极输入端，该电源包括输出端，其中，该过压过流保护电路包括：
    过压侦测单元，连接于该LED模组的正极输入端以及地之间，用于侦测LED模组的正极输入端的电压而产生一与正极输入端的电压成比例的过压侦测电压；
    过流侦测单元，电连接于该电源的输出端以及地之间，用于侦测LED模组的输入电流而产生一与该输入电流成正比的过流侦测电压；
    LED驱动单元，与该过压侦测单元以及过流侦测单元连接，用于将一参考电压分别转换成与该参考电压成正比的过压参考电压以及过流参考电压，该LED驱动单元并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护；
    参考电压调整单元，用于输出该参考电压至该LED驱动单元；以及
    控制单元，其中，该控制单元存储有一LED特性曲线数据，该LED特性曲线数据反映了LED模组所需的工作电压随时间的变化关系，该控制单元根据该LED特性曲线数据判断LED模组的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元增大所输出的参考电压。
  2. 如权利要求1所述的过压过流保护电路，其中，该LED驱动单元包括一过压侦测端、一过流侦测端以及一参考电压输入端；该过压侦测端用于获取该过压侦测电压，该过流侦测端用于获取该过流侦测电压，该参考电压输入端用于接入参考电压；该参考电压调整单元包括一电压输入端、一电压输出端以及一受控端；该电压输入端与一电压端连接，该电压输出端与该LED驱动单元的参考电压输入端连接而输出该参考电压至该LED驱动单元的参考电压输入端；该控制单元包括一控制端，该控制单元的控制端与该参考电压调整单元的受控端连接。
  3. 如权利要求2所述的过压过流保护电路，其中，该控制单元在LED模组开始工作时获取该LED特性曲线数据中的工作电压的初始值，并实时根据LED模组的工作时间而获得该LED特性曲线数据中的时间对应的电压，该控制单元并在比较当前时间对应的电压与该工作电压的初始值比较的变化幅度大于一预定值时，通过该控制端输出一升压控制信号至该参考电压调整单元的受控端，而控制参考电压调整单元增大该电压输出端所输出的参考电压。
  4. 如权利要求2所述的过压过流保护电路，其中，该过压侦测单元包括串联于该LED模组的正极输入端以及地之间的第一电阻以及第二电阻，该第一电阻以及第二电阻的连接节点上的电压即为该过压侦测电压，该LED驱动单元的过压侦测端与该连接节点连接而获得该过压侦测电压；该过流侦测单元包括一电连接于该电源的输出端以及地之间的第三电阻，该第三电阻的远地端上的电压即为该过流侦测电压，该过流侦测电压与流过该第三电阻上的电流成正比。
  5. 如权利要求4所述的过压过流保护电路，其中，该参考电压调整单元包括第一NMOS管、第二NMOS管以及第四电阻、第五电阻、第六电阻以及第七电阻；该第四电阻以及第五电阻串联于该电压输入端与地之间，该第四电阻以及第五电阻的连接节点构成该电压输出端；该第一NMOS管的源极通过第六电阻接地，漏极与该第四电阻以及第五电阻连接；该第二NMOS管的栅极构成该受控端，该第二NMOS管的源极接地，漏极与该第一NMOS管的栅极连接，同时还通过该第七电阻与电压输入端连接。
  6. 如权利要求1所述的过压过流保护电路，其中，该LED模组还包括至少一个并联于该正极输入端以及地之间的LED串，每一LED串包括串联于该正极输入端以及地之间的多个LED灯。
  7. 如权利要求6所述的过压过流保护电路，其中，该LED特性曲线数据为预先根据该LED模组包括的LED串的特性制定得出。
  8. 一种电子装置，包括电源、LED模组以及过流过压保护电路，该电源用于为该LED模组供电，该LED模组包括正极输入端，该电源包括输出端，其中，该过压过流保护电路包括：
    过压侦测单元，连接于该LED模组的正极输入端以及地之间，用于侦测LED模组的正极输入端的电压而产生一与正极输入端的电压成比例的过压侦测电压；
    过流侦测单元，电连接于该电源的输出端以及地之间，用于侦测LED模组的输入电流而产生一与该输入电流成正比的过流侦测电压；
    LED驱动单元，与该过压侦测单元以及过流侦测单元连接，用于将一参考电压分别转换成与该参考电压成正比的过压参考电压以及过流参考电压，该LED驱动单元并将该过压参考电压以及过流参考电压分别与该过压侦测电压以及过流侦测电压进行比较，而决定是否进行过流或过压保护；
    参考电压调整单元，用于输出该参考电压至该LED驱动单元；以及
    控制单元，其中，该控制单元存储有一LED特性曲线数据，该LED特性曲线数据反映了LED模组所需的工作电压随时间的变化关系，该控制单元根据该LED特性曲线数据判断LED模组的工作电压的变化幅度超过一预定值时，控制该参考电压调整单元增大所输出的参考电压。
  9. 如权利要求8所述的电子装置，其中，该LED驱动单元包括一过压侦测端、一过流侦测端以及一参考电压输入端；该过压侦测端用于获取该过压侦测电压，该过流侦测端用于获取该过流侦测电压，该参考电压输入端用于接入参考电压；该参考电压调整单元包括一电压输入端、一电压输出端以及一受控端；该电压输入端与一电压端连接，该电压输出端与该LED驱动单元的参考电压输入端连接而输出该参考电压至该LED驱动单元的参考电压输入端；该控制单元包括一控制端，该控制单元的控制端与该参考电压调整单元的受控端连接。
  10. 如权利要求9所述的电子装置，其中，该控制单元在LED模组开始工作时获取该LED特性曲线数据中的工作电压的初始值，并实时根据LED模组的工作时间而获得该LED特性曲线数据中的时间对应的电压，该控制单元并在比较当前时间对应的电压与该工作电压的初始值比较的变化幅度大于一预定值时，通过该控制端输出一升压控制信号至该参考电压调整单元的受控端，而控制参考电压调整单元增大该电压输出端所输出的参考电压。
  11. 如权利要求9所述的电子装置，其中，该过压侦测单元包括串联于该LED模组的正极输入端以及地之间的第一电阻以及第二电阻，该第一电阻以及第二电阻的连接节点上的电压即为该过压侦测电压，该LED驱动单元的过压侦测端与该连接节点连接而获得该过压侦测电压；该过流侦测单元包括一电连接于该电源的输出端以及地之间的第三电阻，该第三电阻的远地端上的电压即为该过流侦测电压，该过流侦测电压与流过该第三电阻上的电流成正比。
  12. 如权利要求11所述的电子装置，其中，该参考电压调整单元包括第一NMOS管、第二NMOS管以及第四电阻、第五电阻、第六电阻以及第七电阻；该第四电阻以及第五电阻串联于该电压输入端与地之间，该第四电阻以及第五电阻的连接节点构成该电压输出端；该第一NMOS管的源极通过第六电阻接地，漏极与该第四电阻以及第五电阻连接；该第二NMOS管的栅极构成该受控端，该第二NMOS 管的源极接地，漏极与该第一NMOS管的栅极连接，同时还通过该第七电阻与电压输入端连接。
  13. 如权利要求8所述的电子装置，其中，该LED模组还包括至少一个并联于该正极输入端以及地之间的LED串，每一LED串包括串联于该正极输入端以及地之间的多个LED灯。
  14. 如权利要求8所述的电子装置，其中，该LED特性曲线数据为预先根据该LED模组包括的LED串的特性制定得出。
  15. 如权利要求8所述的电子装置，其中，该电子装置为液晶电视、显示器、手机、平板电脑以及笔记本电脑中的一种。
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