WO2020010697A1 - Dc-dc转换电路的过流保护电路、方法及显示面板 - Google Patents

Dc-dc转换电路的过流保护电路、方法及显示面板 Download PDF

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WO2020010697A1
WO2020010697A1 PCT/CN2018/106595 CN2018106595W WO2020010697A1 WO 2020010697 A1 WO2020010697 A1 WO 2020010697A1 CN 2018106595 W CN2018106595 W CN 2018106595W WO 2020010697 A1 WO2020010697 A1 WO 2020010697A1
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Prior art keywords
reference voltage
ocp
overcurrent protection
conversion circuit
voltage
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English (en)
French (fr)
Inventor
张先明
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
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Priority to US16/304,678 priority Critical patent/US20210082327A1/en
Publication of WO2020010697A1 publication Critical patent/WO2020010697A1/zh
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/006—Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays
    • 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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • 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
    • 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
    • H02M3/158—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 including plural semiconductor devices as final control devices for a single load
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/025—Reduction of instantaneous peaks of current
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/028—Generation of voltages supplied to electrode drivers in a matrix display other than LCD
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/04—Display protection

Definitions

  • the present invention relates to the field of display technology, and in particular, to an overcurrent protection circuit, method, and display panel of a DC-DC conversion circuit.
  • the power management chip is a chip (IC) that provides voltage and current in the display panel driver. Its main function is to convert the voltage into various voltages required by the display panel through a DC-DC (direct current-direct current) conversion circuit.
  • the current OCP (Over Current Protection) method of the DC-DC conversion circuit is generally that after the OCP is triggered, the current value will no longer increase and the output voltage will gradually decrease. This may have two consequences. It is part of the voltage drop, but it will not trigger the output undervoltage protection. One is that the output voltage drops too much and triggers the undervoltage protection.
  • FIG. 1 is a schematic diagram of a conventional boost circuit structure.
  • the DC input voltage VIN is processed by a boost circuit composed of an inductor L1, a diode D1, a capacitor C1, and a PWM (pulse width modulation) chip, and then converted into an output voltage Vout;
  • This booster circuit uses the energy storage characteristics of the inductor L1 and the switching tube Q1 to achieve voltage conversion.
  • the inductor L1 converts electrical energy into magnetic field energy and stores it.
  • the switching tube Q1 is turned off, the inductor L1 stores The magnetic field energy is converted into electric field energy, and this energy is superimposed on the input voltage VIN and filtered by the diode D1 and the capacitor C1 to obtain the output voltage Vout.
  • the PWM chip controls the closing and opening of the switch Q1.
  • the output voltage Vout is determined by the pulse.
  • the duty cycle of the wide modulation is determined by the switching time of the switching transistor Q1.
  • a MOS switch Q1 can be built therein, and an OCP current limiter for performing overcurrent protection can also be built in.
  • the OCP current limiter can be controlled by controlling the switch Q1.
  • the switching time controls the output voltage Vout, so as to control the output current and achieve overcurrent protection.
  • the OCP detection voltage V1 is derived from the gate of the NMOS switch Q1.
  • the OCP detection voltage V1 is the OCP current limiter for the boost circuit architecture.
  • the overcurrent protection current is generally reflected by the detected OCP detection voltage V1.
  • the OCP current limiter detects that the OCP detection voltage V1 is greater than a set value, an overcurrent occurs. Protection, OCP current limiter will limit the output current no longer increase.
  • an object of the present invention is to provide an overcurrent protection circuit, method and display panel of a DC-DC conversion circuit, so as to avoid the risk of smoke and fire caused by the existing overcurrent protection circuit due to a large output current.
  • an overcurrent protection circuit of a DC-DC conversion circuit including:
  • the first comparator is used to compare the OCP detection voltage and the first reference voltage in the DC-DC conversion circuit, and output the first comparison result to the logic processor.
  • the first reference voltage is a preset value of the OCP detection voltage during normal operation.
  • a second comparator for comparing the OCP detection voltage with a second reference voltage, and outputting a second comparison result to the logic processor;
  • the second reference voltage is a preset overcurrent protection trigger voltage;
  • the second reference voltage is greater than the first reference Voltage;
  • the logic processor judges the working state of the DC-DC conversion circuit according to the first comparison result and the second comparison result, and outputs a corresponding control signal to the OCP current limiter;
  • the OCP current limiter performs a corresponding overcurrent protection operation on the DC-DC conversion circuit according to the control signal.
  • the OCP detection voltage is limited to be greater than the first reference voltage and smaller than the second reference voltage.
  • the DC-DC conversion circuit is a step-up circuit, a step-down circuit or a step-down boost circuit.
  • the process in which the logic processor determines the working status of the DC-DC conversion circuit includes:
  • the logic processor determines that the DC-DC conversion circuit works normally and does not trigger overcurrent protection
  • the overcurrent protection is not triggered
  • the logic processor determines that the DC-DC conversion circuit is overcurrent, and immediately triggers overcurrent protection, and outputs a corresponding control signal to the OCP current limiter.
  • the overcurrent protection of the OCP current limiter is released.
  • the OCP current limiter limits the OCP detection voltage through pulse width modulation.
  • the non-inverting input terminal of the first comparator inputs the OCP detection voltage, and the inverting input terminal inputs the first reference voltage;
  • the non-inverting input terminal of the second comparator inputs the OCP detection voltage, and the inverting input terminal inputs the first Two reference voltages.
  • the logic processor is a single-chip microcomputer, a CPU, or an FPGA.
  • the present invention also provides a display panel including the over-current protection circuit of the DC-DC conversion circuit according to any one of the above.
  • the invention also provides an over-current protection method for a DC-DC conversion circuit, including:
  • the second reference voltage is a preset overcurrent protection trigger voltage, and the second reference voltage is greater than the first reference voltage
  • the OCP current limiter performs a corresponding overcurrent protection operation on the DC-DC conversion circuit according to the control signal.
  • the OCP detection voltage is limited to be greater than the first reference voltage and less than the second reference voltage.
  • the methods for determining the working status of the DC-DC conversion circuit include:
  • the logic processor determines that the DC-DC conversion circuit works normally and does not trigger overcurrent protection
  • the overcurrent protection is not triggered
  • the logic processor determines that the DC-DC conversion circuit is overcurrent, and immediately triggers overcurrent protection, and outputs a corresponding control signal to the OCP current limiter.
  • the over-current protection circuit, method and display panel of the DC-DC conversion circuit of the present invention not only implement the original over-current protection circuit function and the magnitude of the current that triggers the over-current protection, but also after the over-current protection occurs Limit the size of the output current to prevent the risk of smoke and fire caused by large currents, and achieve the best overcurrent protection.
  • FIG. 1 is a schematic diagram of a conventional booster circuit architecture
  • FIG. 2 is a schematic circuit diagram of a preferred embodiment of an overcurrent protection circuit of a DC-DC conversion circuit according to the present invention.
  • FIG. 2 is a schematic circuit diagram of a preferred embodiment of an overcurrent protection circuit of a DC-DC conversion circuit according to the present invention.
  • the overcurrent protection circuit of the present invention can be implemented on the basis of an existing overcurrent protection circuit and can be implemented. The function of the original overcurrent protection circuit, and the magnitude of the current that triggers the overcurrent protection.
  • the overcurrent protection circuit shown in FIG. 2 can be understood in conjunction with the boost circuit shown in FIG. 1, and other DC-DC conversion circuits can also use the present invention, such as a buck circuit and a buck-boost (Buck- Boost) circuit.
  • the overcurrent protection circuit mainly includes a first comparator OP1, a second comparator OP2, a logic processor, and an OCP current limiter.
  • the non-inverting input terminal of the first comparator OP1 inputs the OCP detection voltage V1 and the inverting input terminal inputs the first reference voltage Vref1;
  • the non-inverting input terminal of the second comparator OP2 inputs the OCP detection voltage V1 and inverts
  • the phase input terminal inputs a second reference voltage Vref2.
  • the logic processor can be a microcontroller, a CPU, or an FPGA.
  • the first comparator OP1 is used to compare the OCP detection voltage V1 and the first reference voltage Vref1 in the DC-DC conversion circuit, and output the first comparison result EN1 to the logic processor.
  • the second comparator OP2 compares the OCP detection voltage V1 and the first reference voltage Vref1.
  • the two reference voltages Vref2 output a second comparison result EN2 to the logic processor.
  • the detection of the OCP detection voltage V1 in the present invention is mainly divided into two parts, one is a preset first reference voltage Vref1, and the size can be about the upper limit voltage of the OCP detection voltage V1 during normal operation, and one is a preset
  • the second reference voltage Vref2 is a voltage when the OCP is triggered, and the second reference voltage Vref2 may be the same as an existing voltage for triggering overcurrent protection; wherein the second reference voltage Vref2> the first reference voltage Vref1.
  • the first comparison result EN1 and the second comparison result EN2 output by the first comparator OP1 and the second comparator OP2 may be 0 or 1.
  • the logic processor judges the working status of the DC-DC conversion circuit according to the first comparison result EN1 and the second comparison result EN2, and outputs a corresponding control signal to the OCP current limiter; the OCP current limiter executes the DC-DC conversion circuit according to the control signal
  • the OCP detection voltage V1 is limited to be slightly greater than the first reference voltage Vref1, and may be limited to less than five percent greater than the first reference voltage Vref1, and less than the second Reference voltage Vref2 to prevent high current.
  • a normal workflow can include the following processes.
  • the OCP detection voltage V1 is less than or equal to the first reference voltage Vref1, it proves that the DC-DC conversion circuit is working normally and will not trigger overcurrent protection of the OCP current limiter.
  • the OCP current limiter's overcurrent protection will not be triggered.
  • OCP current limiter and DC-DC conversion circuit still maintain the original working state; if the previous OCP detection voltage V1 was greater than the second reference voltage Vref2, the second comparison result EN2 obtained by the logic processor is changed from 1 A value of 0 indicates that the overcurrent protection of the OCP current limiter has been triggered in the previous period, and the first comparison result EN1 is 1 at this time, indicating that the OCP current limiter is still performing overcurrent protection without releasing the overcurrent protection, and the OCP current limiter The converter and the DC-DC conversion circuit are in an overcurrent protection working state.
  • the OCP current limiter is immediately triggered to limit the current, and the logic processor outputs a corresponding control signal to the OCP current limiter.
  • the current limiting mode of the OCP current limiter is that if the protection of the second reference voltage Vref2 is triggered, the OCP detection voltage V1 is limited to a value slightly greater than the first reference voltage Vref1 by the OCP current limiter to limit the current and prevent the current Increase to prevent long-time extraction of large currents, while the output voltage gradually decreases.
  • the OCP detection voltage V1 must be lowered to a period lower than the first reference voltage Vref1 for a period of time. That is, the corresponding current is reduced for a period of time.
  • the first comparison result EN1 changes from 1 to 0, and the logic processor can output a control signal to notify the OCP current limiter to release all current overcurrent protections.
  • the OCP current limiter will be triggered for overcurrent protection only after both the first comparison result EN1 / the second comparison result EN2 meet the overcurrent protection trigger condition, that is, the first comparison Result EN1 /
  • the second comparison result EN2 is 1; after the overcurrent protection is triggered, the OCP detection voltage V1 is set to be slightly larger than the first reference voltage Vref1 by the OCP current limiter. At this time, the second comparison result EN2 is 0, then Only after the first comparison result EN1 becomes 0 again, the logic processor can trigger the OCP current limiter to release the overcurrent protection state.
  • the OCP current limiter can use the existing OCP current limiter to affect the OCP detection voltage V1 through pulse width modulation.
  • the PWM chip can control the output voltage Vout by controlling the switching time of the NMOS switch Q1.
  • the OCP detection voltage V1 is controlled. Since the current detection is generally obtained by voltage detection, the OCP current limiter can set the OCP detection voltage V1 to be slightly larger than the first reference voltage Vref1 for overcurrent protection. .
  • the present invention also provides a display panel, which includes the over-current protection circuit of the DC-DC conversion circuit as described above.
  • the invention also correspondingly provides an over-current protection method of a DC-DC conversion circuit, which can be implemented based on the above-mentioned over-current protection circuit or a display panel.
  • the method mainly includes:
  • the first reference voltage Vref1 is a preset upper limit voltage of the OCP detection voltage V1 during normal operation
  • the second reference voltage Vref2 is a preset overcurrent protection trigger voltage, and the second reference voltage Vref2 is greater than the first reference voltage Vref1;
  • the OCP current limiter performs a corresponding overcurrent protection operation on the DC-DC conversion circuit according to the control signal.
  • the OCP detection voltage V1 is limited to be slightly larger than the first reference voltage Vref1.
  • the present invention improves the overcurrent protection method by using two determination standards, one is the reference value for normal operation, that is, the first reference voltage Vref1, and the other is the overcurrent protection value, that is, the second reference voltage Vref2, which triggers the overcurrent protection. After that, the current is limited to the normal working reference value to prevent long-time extraction of large current. If it is lower than the reference value, the overcurrent protection value can be released again.
  • the over-current protection circuit, method and display panel of the DC-DC conversion circuit of the present invention not only implement the original over-current protection circuit function and the magnitude of the current that triggers the over-current protection, but also after the over-current protection occurs Limit the size of the output current to prevent the risk of smoke and fire caused by large currents, and achieve the best overcurrent protection.

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  • Physics & Mathematics (AREA)
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Abstract

本申请涉及一种DC-DC转换电路的过流保护电路、方法及显示面板。该过流保护电路包括：第一比较器(OP1)，用于比较DC-DC转换电路中OCP侦测电压(V1)和第一参考电压(Vref1)，输出第一比较结果(EN1)至逻辑处理器；第二比较器(OP2)，用于比较OCP侦测电压(V1)和第二参考电压(Vref2)，输出第二比较结果(EN2)至逻辑处理器；逻辑处理器，根据第一比较结果(EN1)和第二比较结果(EN2)判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；OCP限流器，根据控制信号对DC-DC转换电路执行相应的过流保护操作。本申请既实现了原有的过流保护电路功能，及触发过流保护的电流大小，又在过流保护发生后限制住输出电流的大小防止大电流导致冒烟起火的风险。

Description

DC-DC转换电路的过流保护电路、方法及显示面板 技术领域
本发明涉及显示技术领域，尤其涉及一种DC-DC转换电路的过流保护电路、方法及显示面板。
背景技术
电源管理芯片(PM IC)是显示面板驱动中提供电压与电流的芯片(IC)，其主要作用是通过DC-DC(直流-直流)转换电路将电压转换为显示面板所需要的各种电压。
现在的DC-DC转换电路的OCP(Over Current Protection,过流保护)的方式一般为在触发OCP后，使电流值不再增加，同时输出电压会逐渐下降，这样可能会出现两种后果，一是电压下降一部分，但是并不会触发输出的欠压保护，一种是输出电压下降太多，触发欠压保护。
对于未触发欠压保护的情况下，由于输出大电流，会造成整个DC-DC转换电路工作在一种危险的状态，甚至触发冒烟起火的危险。
图1为现有一种升压(Boost)电路架构示意图，直流输入电压VIN经电感L1，二极管D1，电容C1以及PWM(脉宽调制)芯片组成的升压电路处理后，转换为输出电压Vout；该升压电路利用电感L1的储能特性以及开关管Q1来实现电压的变换；当开关管Q1闭合后，电感L1将电能转换为磁场能储存起来，当开关管Q1断开后电感L1将储存的磁场能转换为电场能，且这个能量在和输入电压VIN叠加后通过二极管D1和电容C1的滤波后得到输出电压Vout；PWM芯片控制开关管Q1的闭合、断开，输出电压Vout大小由脉宽调制的占空比即开关管Q1的开关时间决定。在此作为举例的升压电路架构中，对于PWM芯片，其中可以内置MOS开关管Q1，并且还可以内置用于执行过流保护的OCP限流器，OCP限流器可以通过控制开关管Q1的开关时间控制输出电压Vout，从而控制输出电流，实现过流保护；OCP侦测电压V1自NMOS开关管Q1的栅极引出，OCP侦测电压V1即为OCP限流器对所在升压电路架构的侦测，过流保护电流一般是通过侦测到的OCP侦测电压V1体现，现有技术中一般设计为如果OCP限流器侦测到OCP侦测电压V1大于设定值，即发生过流保护，OCP限流器将限定输出电流不再增加。
发明内容
因此，本发明的目的在于提供一种DC-DC转换电路的过流保护电路、方法及显示面板，避免现有过流保护电路由于输出大电流导致冒烟起火的风险。
为实现上述目的，本发明提供了一种DC-DC转换电路的过流保护电路，包括：
第一比较器，用于比较DC-DC转换电路中OCP侦测电压和第一参考电压，输出第一比较结果至逻辑处理器，第一参考电压为预设的正常工作时OCP侦测电压的上限电压；
第二比较器，用于比较OCP侦测电压和第二参考电压，输出第二比较结果至逻辑处理器，第二参考电压为预设的过流保护触发电压，第二参考电压大于第一参考电压；
逻辑处理器，根据第一比较结果和第二比较结果判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；
OCP限流器，根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压限制到大于第一参考电压且小于第二参考电压。
其中，所述DC-DC转换电路为升压电路、降压电路或降压升压电路。
其中，所述逻辑处理器判断DC-DC转换电路工作状态的过程包括：
若OCP侦测电压小于等于第一参考电压，所述逻辑处理器判断DC-DC转换电路正常工作，不触发过流保护；
若OCP侦测电压大于第一参考电压且小于等于第二参考电压，只要在此之前OCP侦测电压未曾大于第二参考电压，不触发过流保护；
若OCP侦测电压大于第二参考电压，所述逻辑处理器判断DC-DC转换电路过流工作，则立即触发过流保护，向OCP限流器输出相应的控制信号。
其中，触发过流保护后，当OCP侦测电压下降到低于第一参考电压一段时间后，解除OCP限流器的过流保护。
其中，所述OCP限流器通过脉宽调制来限制OCP侦测电压。
其中，所述第一比较器的同相输入端输入OCP侦测电压，反相输入端输入第一参考电压；所述第二比较器的同相输入端输入OCP侦测电压，反相输入端输入第二参考电压。
其中，所述逻辑处理器为单片机，CPU，或者FPGA。
本发明还提供了一种显示面板，包括如上述任一项所述的DC-DC转换电路的过流保护电路。
本发明还提供了一种DC-DC转换电路的过流保护方法，包括：
比较DC-DC转换电路中OCP侦测电压和第一参考电压，输出第一比较结果，第一参考电压为预设的正常工作时OCP侦测电压的上限电压；
比较OCP侦测电压和第二参考电压，输出第二比较结果，第二参考电压为预设的过流保护触发电压，第二参考电压大于第一参考电压；
根据第一比较结果和第二比较结果判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；
OCP限流器根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压限制到大于第一参考电压且小于第二参考电压。
其中，判断DC-DC转换电路工作状态的方式包括：
若OCP侦测电压小于等于第一参考电压，所述逻辑处理器判断DC-DC转换电路正常工作，不触发过流保护；
若OCP侦测电压大于第一参考电压小于等于第二参考电压，只要在此之前OCP侦测电压未曾大于第二参考电压，不触发过流保护；
若OCP侦测电压大于第二参考电压，所述逻辑处理器判断DC-DC转换电路过流工作，则立即触发过流保护，向OCP限流器输出相应的控制信号。
综上，本发明的DC-DC转换电路的过流保护电路、方法及显示面板既实现了原有的过流保护电路功能，及触发过流保护的电流大小，同时又在过流保护发生后限制住输出电流的大小防止大电流导致冒烟起火的风险，实现了最佳的过流保护。
附图说明
下面结合附图，通过对本发明的具体实施方式详细描述，将使本发明的技术方案及其他有益效果显而易见。
附图中，
图1为现有一种升压电路架构示意图；
图2为本发明DC-DC转换电路的过流保护电路一较佳实施例的电路原理示意图。
具体实施方式
参见图2，其为本发明DC-DC转换电路的过流保护电路一较佳实施例的电路原理示意图，本发明的过流保护电路可以在现有过流保护电路的基础上实现，可实现原有的过流保护电路功能，及触发过流保护的电流大小。图2所示的过流保护电路可以结合图1所示的升压电路来理解，而且其他DC-DC转换电路一样可以沿用本发明，例如降压(Buck)电路以及降压升压(Buck-Boost)电路等。
该过流保护电路主要包括：第一比较器OP1，第二比较器OP2，逻辑处理器，以及OCP限流器。在此实施例中，第一比较器OP1的同相输入端输入OCP侦测电压V1，反相输入端输入第一参考电压Vref1；第二比较器OP2的同相输入端输入OCP侦测电压V1，反相输入端输入第二参考电压Vref2。逻辑处理器可以为单片机，CPU，或者FPGA等。
第一比较器OP1用于比较DC-DC转换电路中OCP侦测电压V1和第一参考电压Vref1，输出第一比较结果EN1至逻辑处理器；第二比较器OP2比较OCP侦测电压V1和第二参考电压Vref2，输出第二比较结果EN2至逻辑处理器。本发明针对OCP侦测电压V1的侦测主要分为两个部分，一个为预设的第一参考电压Vref1，大小可以为正常工作时OCP侦测电压V1的上限电压左右，一个为预设的第二参考电压Vref2，为触发OCP时的电压，第二参考电压Vref2可以与现有的触发过流保护的电压一致；其中第二参考电压Vref2＞第一参考电压Vref1。根据输入，第一比较器OP1和第二比较器OP2输出的第一比较结果EN1和第二比较结果EN2可以为0或1。
逻辑处理器根据第一比较结果EN1和第二比较结果EN2判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；OCP限流器根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压V1限制到略大于第一参考电压Vref1，可以限制为大于第一参考电压Vref1百分之五以内，并且小于第二参考电压Vref2，以防止大电流。正常工作流程可以包括如下过程。
若OCP侦测电压V1小于或等于第一参考电压Vref1，则证明DC-DC转换电路在正常工作，不会触发OCP限流器的过流保护。
若OCP侦测电压V1大于第一参考电压Vref1且小于或等于第二参考电压Vref2，只要在前期OCP侦测电压V1没有触发大于第二参考电压Vref2，则不触发OCP限流器的过流保护，OCP限流器和DC-DC转换电路仍然保持原有的工作状态；若前期OCP侦测电压V1曾经大于第二参考电压Vref2，即逻辑处理器所获的第二比较结果EN2是由1变成0，说明前期已经触发过OCP限流器的过流保护，而此时第一比较结果EN1为1，说明OCP限 流器当前仍在进行过流保护而未解除过流保护，OCP限流器和DC-DC转换电路处于过流保护工作状态。
若OCP侦测电压V1大于第二参考电压Vref2，则立即触发OCP限流器进行限流，由逻辑处理器向OCP限流器输出相应的控制信号。OCP限流器限流的工作模式为若触发第二参考电压Vref2的保护，通过OCP限流器将OCP侦测电压V1限制到略大于第一参考电压Vref1处，以限制电流，使电流不再增加，防止大电流的长时间抽取，同时输出电压逐渐下降。OCP限流器开始进行过流保护后，若要解除OCP限流器的限流，就要使OCP侦测电压V1下降到低于第一参考电压Vref1一段时间，时间长短可由逻辑处理器判定，也就是使相应的电流下降一段时间，此时第一比较结果EN1由1变为0，即可由逻辑处理器输出控制信号以通知OCP限流器解除当前所有过流保护。
在此实施例中，对于逻辑处理器来说，只有第一比较结果EN1/第二比较结果EN2都满足过流保护触发条件后才会触发OCP限流器进行过流保护，也就是第一比较结果EN1/第二比较结果EN2都为1；在触发过流保护后通过OCP限流器将OCP侦测电压V1设置为略大于第一参考电压Vref1，这个时候第二比较结果EN2为0，那么只有第一比较结果EN1再次变为0后，逻辑处理器才能触发OCP限流器解除过流保护状态。
OCP限流器可以采用现有的OCP限流器，通过脉宽调制来影响OCP侦测电压V1，以图1为例，PWM芯片可通过控制NMOS开关管Q1的开关时间来控制输出电压Vout，进而控制了OCP侦测电压V1，由于电流的侦测一般是通过电压侦测得到的，因而OCP限流器可以通过将OCP侦测电压V1设置为略大于第一参考电压Vref1以进行过流保护。
本发明还相应提供了一种显示面板，包含如上所述的DC-DC转换电路的过流保护电路。
本发明还相应提供了一种DC-DC转换电路的过流保护方法，该方法可以基于上述过流保护电路或显示面板进行实施。该方法主要包括：
比较DC-DC转换电路中OCP侦测电压V1和第一参考电压Vref1，输出第一比较结果EN1，第一参考电压Vref1为预设的正常工作时OCP侦测电压V1的上限电压；
比较OCP侦测电压V1和第二参考电压Vref2，输出第二比较结果EN2，第二参考电压Vref2为预设的过流保护触发电压，第二参考电压Vref2大于第一参考电压Vref1；
根据第一比较结果EN1和第二比较结果EN2判断DC-DC转换电路工 作状态，并向OCP限流器输出相应的控制信号；
OCP限流器根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压V1限制到略大于第一参考电压Vref1。
本发明改善过流保护方法，使用两种判定标准，一种为正常工作的基准值，即第一参考电压Vref1，一种为过流保护值，即第二参考电压Vref2，在触发过流保护后，限流至正常工作的基准值，防止大电流的长时间抽取，若再低于基准值，就可以再次放开过流保护值。
综上，本发明DC-DC转换电路的的过流保护电路、方法及显示面板既实现了原有的过流保护电路功能，及触发过流保护的电流大小，同时又在过流保护发生后限制住输出电流的大小防止大电流导致冒烟起火的风险，实现了最佳的过流保护。
以上所述，对于本领域的普通技术人员来说，可以根据本发明的技术方案和技术构思作出其他各种相应的改变和变形，而所有这些改变和变形都应属于本发明后附的权利要求的保护范围。

Claims (10)

  1. 一种DC-DC转换电路的过流保护电路，包括：
    第一比较器，用于比较DC-DC转换电路中OCP侦测电压和第一参考电压，并输出第一比较结果至逻辑处理器，第一参考电压为预设的DC-DC转换电路正常工作时OCP侦测电压的上限电压；
    第二比较器，用于比较OCP侦测电压和第二参考电压，并输出第二比较结果至逻辑处理器，第二参考电压为预设的过流保护触发电压，第二参考电压大于第一参考电压；
    逻辑处理器，根据第一比较结果和第二比较结果判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；
    OCP限流器，根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压限制到大于第一参考电压且小于第二参考电压。
  2. 如权利要求1所述的DC-DC转换电路的过流保护电路，其中，所述DC-DC转换电路为升压电路、降压电路或降压升压电路。
  3. 如权利要求1所述的DC-DC转换电路的过流保护电路，其中，所述逻辑处理器判断DC-DC转换电路工作状态的过程包括：
    若OCP侦测电压小于等于第一参考电压，所述逻辑处理器判断DC-DC转换电路正常工作，不触发过流保护；
    若OCP侦测电压大于第一参考电压且小于等于第二参考电压，只要在此之前OCP侦测电压未曾大于第二参考电压，不触发过流保护；
    若OCP侦测电压大于第二参考电压，逻辑处理器判断DC-DC转换电路过流工作，立即触发过流保护，向OCP限流器输出相应的控制信号。
  4. 如权利要求3所述的DC-DC转换电路的过流保护电路，其中，触发过流保护后，当OCP侦测电压下降到低于第一参考电压一段时间后，OCP限流器解除过流保护。
  5. 如权利要求3所述的DC-DC转换电路的过流保护电路，其中，所述OCP限流器通过脉宽调制来限制OCP侦测电压。
  6. 如权利要求1所述的DC-DC转换电路的过流保护电路，其中，所述第一比较器的同相输入端输入OCP侦测电压，反相输入端输入第一参考电压；所述第二比较器的同相输入端输入OCP侦测电压，反相输入端输入第二参考电压。
  7. 如权利要求1所述的DC-DC转换电路的过流保护电路，其中，所述逻辑处理器为单片机，CPU，或者FPGA。
  8. 一种显示面板，包括如上述权利要求1所述的DC-DC转换电路的过流保护电路。
  9. 一种DC-DC转换电路的过流保护方法，包括：
    比较DC-DC转换电路中OCP侦测电压和第一参考电压，输出第一比较结果，第一参考电压为预设的正常工作时OCP侦测电压的上限电压；
    比较OCP侦测电压和第二参考电压，输出第二比较结果，第二参考电压为预设的过流保护触发电压，第二参考电压大于第一参考电压；
    根据第一比较结果和第二比较结果判断DC-DC转换电路工作状态，并向OCP限流器输出相应的控制信号；
    OCP限流器根据控制信号对DC-DC转换电路执行相应的过流保护操作，当开始执行过流保护时，将OCP侦测电压限制到大于第一参考电压且小于第二参考电压。
  10. 如权利要求9所述的DC-DC转换电路的过流保护方法，其中，判断DC-DC转换电路工作状态的方式包括：
    若OCP侦测电压小于等于第一参考电压，所述逻辑处理器判断DC-DC转换电路正常工作，不触发过流保护；
    若OCP侦测电压大于第一参考电压小于等于第二参考电压，只要在此之前OCP侦测电压未曾大于第二参考电压，不触发过流保护；
    若OCP侦测电压大于第二参考电压，所述逻辑处理器判断DC-DC转换电路过流工作，立即触发过流保护，向OCP限流器输出相应的控制信号。
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