WO2014107926A1 - Led驱动电路 - Google Patents

Led驱动电路 Download PDF

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Publication number
WO2014107926A1
WO2014107926A1 PCT/CN2013/070979 CN2013070979W WO2014107926A1 WO 2014107926 A1 WO2014107926 A1 WO 2014107926A1 CN 2013070979 W CN2013070979 W CN 2013070979W WO 2014107926 A1 WO2014107926 A1 WO 2014107926A1
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WIPO (PCT)
Prior art keywords
circuit
voltage
transformer
resistor
terminal
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PCT/CN2013/070979
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English (en)
French (fr)
Inventor
曹丹
杨翔
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深圳市华星光电技术有限公司
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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 US13/824,396 priority Critical patent/US8866413B2/en
Publication of WO2014107926A1 publication Critical patent/WO2014107926A1/zh

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    • 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
    • H05B45/395—Linear regulators
    • 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 invention relates to an LED driving circuit, in particular to an LED driving circuit without a power management IC.
  • the drive circuit is an important part of LED application products, and its technology maturity is gradually increasing with the expansion of the LED market. Whether in lighting, backlight or display panels, a number of mature drive circuit products have emerged.
  • a power management IC to control.
  • the commonly used power management ICs generally have a relatively complicated structure and a high price.
  • the overall structure of the driving circuit is complicated, and it is also disadvantageous for reducing the manufacturing cost of the driving circuit.
  • the technical problem to be solved by the present invention is to provide an LED driving circuit for reducing the manufacturing cost by replacing the power management IC with respect to the above-mentioned defects of the complicated structure and high cost of the LED driving circuit in the prior art.
  • an LED driving circuit wherein the driving circuit comprises a transformer, a MOS tube, a power adjusting resistor, a DC isolation circuit, a rectifier circuit and a voltage control circuit;
  • the transformer includes a first winding and a second winding, one end of the first winding is connected to an external power source, the other end is connected to a source of the MOS tube, and a drain of the MOS tube is grounded through a power adjusting resistor; One end of the two windings is grounded, and the other end is connected to the gate of the MOS tube through a DC isolation circuit;
  • the voltage control circuit includes a control terminal for controlling on and off of the MOS transistor, a reference terminal for adjusting the voltage of the control terminal, and a ground terminal; the control terminal is connected to an external power source and a gate of the MOS transistor, and the reference terminal Grounded through a power adjustment resistor, the ground terminal is directly grounded;
  • the transformer cooperates with the voltage control circuit to control the on and off of the MOS tube.
  • the current input by the external power source sequentially flows through the first winding of the transformer, the MOS tube and the power adjustment resistor, and the rectifier circuit is turned off;
  • the second winding of the transformer charges the capacitance of the MOS tube through the DC isolation circuit, and the rectifier circuit is turned on, and the first winding of the transformer supplies power to the LED load through the rectifier circuit.
  • the rectifier circuit is a rectifier diode.
  • the voltage control circuit comprises a TL432 chip or a TL431 chip.
  • the DC isolation circuit comprises a DC isolation capacitor and a DC isolation resistor connected in series, the DC isolation capacitor being connected to a second winding of the transformer, the DC isolation resistor being connected to a gate of the MOS transistor.
  • the driving circuit comprises a compensation circuit, an input end of the compensation circuit is connected to a control end of the voltage control circuit, and an output end of the compensation circuit is connected to a reference end of the voltage control circuit.
  • the compensation circuit comprises a compensation resistor and a compensation capacitor connected in series.
  • the driving circuit includes a protection circuit for preventing breakdown of the MOS transistor, an input end of the protection circuit is connected to a control end of the voltage control circuit, an output end of the protection circuit and the voltage control circuit Ground connection.
  • the protection circuit comprises a Zener diode and a protection resistor connected in parallel.
  • a control terminal voltage regulating resistor is connected between the control end of the voltage control circuit and the external power source, and the control terminal voltage regulating resistor is used to adjust the voltage of the control terminal of the voltage control circuit.
  • a reference terminal voltage regulating resistor is connected between the reference end of the voltage control circuit and the power adjusting resistor, and the reference terminal voltage regulating resistor is used to adjust the reference terminal voltage of the voltage control circuit.
  • the driving circuit includes a transformer, a MOS transistor, a power adjusting resistor, a DC isolation circuit, a rectifier circuit, and a voltage control circuit; and a source receiving transformer of the MOS transistor Input voltage, the drain of the MOS transistor is grounded through a power adjustment resistor; the gate of the MOS transistor receives the output voltage of the transformer through a DC isolation circuit;
  • the voltage control circuit includes a control terminal for controlling on and off of the MOS transistor, a reference terminal for adjusting the voltage of the control terminal, and a ground terminal; the control terminal receives an output voltage of the external power source and is connected to the gate of the MOS transistor The ground end is directly grounded, and the reference end is grounded through a power adjustment resistor;
  • the transformer cooperates with the voltage control circuit to control the on and off of the MOS tube.
  • the input voltage of the transformer forms a current in the transformer, the MOS tube and the power adjustment resistor; when the MOS tube is turned off, the output of the transformer
  • the voltage is charged by the transformer, the DC isolation circuit and the MOS tube for the capacitance of the MOS tube, and the transformer supplies power to the LED load through the rectifier circuit.
  • the rectifier circuit is a rectifier diode.
  • the voltage control circuit comprises a TL432 chip or a TL431 chip.
  • the DC isolation circuit includes a DC isolation capacitor and a DC isolation resistor connected in series, the DC isolation capacitor receiving an output voltage of the transformer.
  • the driving circuit further comprises a compensation circuit, an input end of the compensation circuit receives an output voltage of an external power source, and an output end of the compensation circuit is grounded through the power adjustment resistor.
  • the compensation circuit comprises a compensation resistor and a compensation capacitor connected in series.
  • the driving circuit further comprises a protection circuit for preventing breakdown of the MOS transistor, the input end of the protection circuit receiving an output voltage of the external power source, and the output end of the protection circuit is directly grounded.
  • the protection circuit comprises a Zener diode and a protection resistor connected in parallel.
  • the control end of the voltage control circuit receives the output voltage of the external power source through the control terminal voltage regulating resistor, and the control terminal voltage regulating resistor is used to adjust the voltage of the control terminal of the voltage control circuit.
  • a reference terminal voltage regulating resistor is connected between the reference end of the voltage control circuit and the power adjusting resistor, and the reference terminal voltage regulating resistor is used to adjust the reference terminal voltage of the voltage control circuit.
  • a transformer and a TL432 chip or a TL431 chip can be used to replace the existing complicated and expensive power management IC, thereby simplifying the LED driving circuit and reducing the manufacturing cost.
  • FIG. 1 is a block diagram showing the structure of a preferred embodiment of an LED driving circuit of the present invention
  • FIG. 2 is a circuit diagram of a preferred embodiment of the LED drive circuit of the present invention.
  • the present invention provides an LED driving circuit that uses a transformer, a MOS transistor, and a voltage control circuit (preferably an existing TL432 chip or TL431 chip) to replace the existing power management IC to control the driving circuit.
  • a voltage control circuit preferably an existing TL432 chip or TL431 chip
  • the LED driving circuit of the present invention comprises a transformer, a MOS tube, a power adjusting resistor, a rectifying circuit, a voltage control circuit and a DC isolation circuit, wherein the power adjusting resistor is used for adjusting the power of the entire driving circuit, and the transformer is double Winding transformer, one end of the first winding NP is connected to the existing external power source, the received voltage is the input voltage of the transformer, one end of the second winding NA is grounded; the voltage control circuit includes control for controlling the on and off of the MOS tube The terminal, the reference terminal for adjusting the voltage of the control terminal, and the ground terminal, wherein the control terminal and the external power source are respectively connected with the gate of the MOS tube, the reference terminal is grounded through the power adjustment resistor, and the ground terminal is directly grounded.
  • the MOS transistor is an N-channel MOS transistor.
  • One end of the first winding NP of the transformer is connected to an external power source, and the other end is connected to the source of the MOS tube.
  • the drain of the MOS tube is grounded through a power adjustment resistor; one end of the second winding NA of the transformer is grounded, and the other end is connected to the gate of the MOS tube through a DC isolation circuit, and the output voltage of the second winding of the transformer is the output voltage of the transformer;
  • the first winding NP of the transformer is in turn connected to the LED load via a rectifier circuit.
  • the first winding NP is used to power the LED load
  • the second winding NA is used to charge the capacitance of the MOS transistor.
  • one end of the first winding NP connected to the external power source is a positive pole
  • one end connected to the source of the MOS tube is a negative pole
  • one end of the second winding NA is grounded at one side and the other end is a negative pole.
  • one end of the first winding NP connected to the external power source is a negative pole
  • one end connected to the source of the MOS tube is a positive pole
  • one end of the second winding NA is grounded at a negative pole
  • the other end is a positive pole.
  • a rectifier circuit for converting alternating current from a transformer to an LED load to direct current is usually composed of a main circuit, a filter, etc., and the filter is connected between the main circuit and the load to filter out the AC component in the pulsating DC voltage; the main circuit is composed of a silicon rectifier diode and a thyristor.
  • a rectifier diode can be used instead of the rectifier circuit, and the rectifier diode uses the unidirectional conduction characteristic of the PN junction to change the alternating current from the first winding NP into a pulsating direct current.
  • MOS tube is used to control the current between the transformer and the LED load.
  • the rectifier circuit is cut off, and the transformer and the LED load are disconnected.
  • the MOS tube is turned off, the rectifier circuit is turned on, and the transformer and the LED load are turned on. For the pathway.
  • the voltage control circuit is used for controlling the MOSFET to be turned on and off. When the voltage of the control terminal is higher than the threshold voltage of the MOS transistor, the MOS transistor is turned on, and when the voltage of the control terminal is lower than the threshold voltage of the MOS transistor, the MOS transistor is turned off.
  • the voltage control circuit is an existing TL432 chip or a TL431 chip. In this embodiment, the TL432 chip is used, the cathode C corresponds to the control end, the anode A corresponds to the ground end, the reference end R corresponds to the reference end, and the reference voltage of the TL432 chip is 1.249V. The reference voltage of the TL431 chip is 2.5V.
  • the power adjustment resistor can adjust the voltage of the reference terminal of the voltage control circuit.
  • the voltage control circuit adjusts the voltage of the control terminal to a low voltage state, and the MOS transistor is turned off.
  • a DC isolation circuit is used to prevent DC current from entering the second winding of the transformer.
  • the voltage input by the external power supply increases from zero to a preset fixed value, and the voltage of the control terminal of the voltage control circuit increases as the input voltage increases.
  • the control terminal of the voltage control circuit is in a high voltage state, when the voltage of the control terminal of the voltage control circuit is higher than the threshold voltage of the MOS transistor, The MOS tube is turned on, and the current input from the external power source sequentially flows through the first winding of the transformer, the MOS tube and the power adjustment resistor, while the transformer T1 stores energy, the rectifier circuit is cut off, and the transformer and the LED load are disconnected; the voltage of the power adjustment resistor is The current flowing through the power adjustment resistor increases, and when the voltage of the power adjustment resistor is approximately equal to the voltage of the reference terminal of the voltage control circuit, the voltage control circuit adjusts the control terminal to a low voltage state, the MOS transistor is turned off, and the second of the transformer The winding charges the capacitance of the
  • the above process is repeated periodically, and the present invention controls the LED driving circuit through a voltage control circuit and a transformer.
  • the voltage control circuit can be replaced by a TL432 chip or a TL431 chip;
  • the DC isolation circuit can be replaced by a series DC blocking capacitor and a DC isolation resistor, wherein the DC isolation capacitor is connected to the second winding of the transformer, and the DC isolation resistor Connected to the gate of the MOS transistor.
  • the LED driving circuit may further include a compensation circuit, the input end of the compensation circuit is connected to the control end of the voltage control circuit, and the output end of the cover compensation circuit is connected to the reference end of the voltage control circuit.
  • the compensation circuit can also include a compensation resistor and a compensation capacitor in series.
  • the driving circuit may further include a protection circuit for preventing breakdown of the MOS transistor, the input end of the protection circuit is connected to the control end of the voltage control circuit, and the output terminal and voltage control of the protection circuit The ground terminal of the circuit is connected, and the protection circuit may further include a Zener diode and a protection resistor connected in parallel.
  • a control terminal voltage regulating resistor is connected between the control terminal of the voltage control circuit and the external power source, and the voltage regulating resistor is used to adjust the voltage of the control terminal of the voltage control circuit.
  • a reference terminal voltage regulating resistor is connected between the reference terminal of the voltage control circuit and the power adjusting resistor, and the reference terminal voltage regulating resistor is used to adjust the reference terminal voltage of the voltage control circuit.
  • FIG. 2 is a circuit diagram of the LED driving circuit of the present invention shown in FIG. 1.
  • the transformer is T1, and one end of the first winding NP is connected to an external power source, and the other end is connected to the source of the MOS transistor Q1.
  • the drain of the MOS transistor is grounded via the power adjusting resistor R6;
  • the second winding NA of the transformer T1 is grounded at one end, and the other end is connected to the gate of the MOS transistor Q1 via a DC isolation capacitor C1 and a DC isolation resistor R2.
  • the voltage control circuit is a TL432 chip, the cathode C of the TL432 chip is respectively connected to the external power source and the gate of the MOS transistor Q1, and the control terminal voltage regulating resistor R1 is connected between the cathode C and the external power source, the anode A of the TL432 chip is grounded, and the TL432 chip is The reference terminal R is grounded through the reference terminal voltage regulating resistor R5 and the power adjusting resistor R6.
  • the protection circuit is a Zener diode ZD1 and a protection resistor R4 connected in parallel, and the Zener diode ZD1 and the protection resistor R4 are connected in parallel to the cathode C and the anode A of the TL432 chip.
  • the compensation circuit is a series compensation resistor R3 and a compensation capacitor C2, and the current input from the external power source flows through the control terminal voltage regulating resistor R1, the compensation resistor R3, the compensation capacitor C2, the reference terminal voltage regulating resistor R5 and the power adjusting resistor R6.
  • the rectifier circuit is a rectifier diode D1.
  • the LED load is a parallel third capacitor C3 and four light emitting diodes D10-D13.
  • the voltage of the cathode terminal C of the TL432 chip increases with the increase of the input voltage Vin.
  • the MOS transistor Q1 is turned on, so that the input current flows through the transformer.
  • the second winding NA is upper and lower positive, no current flows through the DC isolation capacitor C1 and the DC isolation resistor R2); as the current flowing through the power adjustment resistor R6 increases, The voltage above R6 keeps increasing.
  • the voltage of R6 is close to the reference voltage of 1.249V of TL432 chip, the voltage of cathode segment C will be pulled down to the low level inside the TL432 chip, and the gate voltage is lower than the threshold voltage of MOS transistor Q1.
  • the MOS transistor Q1 will be turned off.
  • the transformer T1 releases energy
  • the second winding NA charges the capacitance of the MOS transistor Q1
  • the rectifier diode D1 is turned on
  • the first winding NP supplies power to the LED load (NP is up and down)
  • NA is positive and negative
  • a current flows through the DC isolation capacitor C1 and the DC isolation resistor R2).
  • the MOS transistor Q1 is turned back on. Repeat the above process in this way. This allows the LED driver circuit to be controlled by the TL432 chip and transformer T1.

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Abstract

公开了一种LED驱动电路，该驱动电路包括变压器（T1）、MOS管（Q1）、功率调整电阻（R6）、直流隔离电路、整流电路和电压控制电路；电压控制电路的控制端电压高于MOS管（Q1）的阈值电压时，MOS管（Q1）导通，外部电源输入的电流依次流过变压器的第一绕组（NP）、MOS管（Q1）和功率调整电阻（R6），整流电路截止；功率调整电阻（R6）的电压与电压控制电路基准端的电压的近似时，MOS管截止（Q1），变压器的第二绕组（NA）通过直流隔离电路为MOS管（Q1）的电容充电，整流电路导通，变压器的第一绕组（NP）通过整流电路向LED负载供电，MOS管（Q1）的电容电压高于阈值电压时，MOS管（Q1）又导通。采用该LED驱动电路，可替代电源管理IC，简化LED驱动电路、降低成本。

Description

LED驱动电路 技术领域
本发明涉及一种LED驱动电路，尤其涉及一种无电源管理IC的LED驱动电路。
背景技术
驱动电路是LED应用产品的重要组成部分，其技术成熟度正随着LED市场的扩张而逐步增强。无论在照明、背光源还是显示板方面，都涌现出了一批成熟的驱动电路产品。目前，现有的这些驱动电路大多数都需要电源管理IC来控制。然而，常用的电源管理IC一般都具有较复杂的结构和较高的价格，用于LED驱动电路时会使得驱动电路整体结构复杂化，也不利于降低驱动电路的制造成本。
发明内容
本发明要解决的技术问题在于，针对现有技术中LED驱动电路结构繁复、成本高的上述缺陷，提供一种通过替代电源管理IC来降低制造成本的LED驱动电路。
本发明解决其技术问题所采用的技术方案是：一种LED驱动电路，其中，所述驱动电路包括变压器、MOS管、功率调整电阻、直流隔离电路、整流电路和电压控制电路；
所述变压器包括第一绕组与第二绕组，所述第一绕组的一端与外部电源连接，另一端与MOS管的源极连接，所述MOS管的漏极通过功率调整电阻接地；所述第二绕组的一端接地，另一端通过直流隔离电路与所述MOS管的栅极连接；
所述电压控制电路包括用于控制MOS管通断的控制端、用于调整控制端电压的基准端、以及接地端；所述控制端与外部电源和MOS管的栅极连接，所述基准端通过功率调整电阻接地，所述接地端直接接地；
所述变压器与所述电压控制电路协作控制MOS管的通断，当MOS管导通时，外部电源输入的电流依次流过变压器的第一绕组、MOS管和功率调整电阻，整流电路截止；当MOS管截止时，变压器的第二绕组通过直流隔离电路为MOS管的电容充电，整流电路导通，变压器的第一绕组通过整流电路向LED负载供电。
优选地，所述整流电路为整流二极管。
优选地，所述电压控制电路包括TL432芯片或TL431芯片。
优选地，所述直流隔离电路包括串联的直流隔离电容和直流隔离电阻，所述直流隔离电容与所述变压器的第二绕组连接，所述直流隔离电阻与所述MOS管的栅极连接。
优选地，所述驱动电路包括补偿电路，所述补偿电路的输入端与所述电压控制电路的控制端连接，所述补偿电路的输出端与所述电压控制电路的基准端连接。
优选地，所述补偿电路包括串联的补偿电阻和补偿电容。
优选地，所述驱动电路包括用于防止MOS管击穿的保护电路，所述保护电路的输入端与所述电压控制电路的控制端连接，所述保护电路的输出端与所述电压控制电路的接地端连接。
优选地，所述保护电路包括并联的稳压二极管和保护电阻。
优选地, 所述电压控制电路的控制端与外部电源之间连接有控制端调压电阻，所述控制端调压电阻用于调节所述电压控制电路的控制端电压。
优选地, 所述电压控制电路的基准端与功率调整电阻之间连接有基准端调压电阻，所述基准端调压电阻用于调节所述电压控制电路的基准端电压。
本发明的另一技术方案提供一种LED驱动电路，其中，所述驱动电路包括变压器、MOS管、功率调整电阻、直流隔离电路、整流电路和电压控制电路；所述MOS管的源极接收变压器的输入电压，所述MOS管的漏极通过功率调整电阻接地；所述MOS管的栅极通过直流隔离电路接收变压器的输出电压；
所述电压控制电路包括用于控制MOS管通断的控制端、用于调整控制端电压的基准端、以及接地端；所述控制端接收外部电源的输出电压，并与MOS管的栅极连接，所述接地端直接接地，所述基准端通过功率调整电阻接地；
所述变压器与所述电压控制电路协作控制MOS管的通断，当MOS管导通时，变压器的输入电压在变压器、MOS管和功率调整电阻中形成电流；当MOS管截止时，变压器的输出电压通过变压器、直流隔离电路和MOS管为MOS管的电容充电，同时变压器通过整流电路向LED负载供电。
优选地，所述整流电路为整流二极管。
优选地，所述电压控制电路包括TL432芯片或TL431芯片。
优选地，所述直流隔离电路包括串联的直流隔离电容和直流隔离电阻，所述直流隔离电容接收所述变压器的输出电压。
优选地，所述驱动电路还包括补偿电路，所述补偿电路的输入端接收外部电源的输出电压，所述补偿电路的输出端通过所述功率调整电阻接地。
优选地，所述补偿电路包括串联的补偿电阻和补偿电容。
优选地，所述驱动电路还包括用于防止MOS管击穿的保护电路，所述保护电路的输入端接收外部电源的输出电压，所述保护电路的输出端直接接地。
优选地，所述保护电路包括并联的稳压二极管和保护电阻。
优选地, 所述电压控制电路的控制端通过控制端调压电阻接收外部电源的输出电压，所述控制端调压电阻用于调节所述电压控制电路的控制端电压。
优选地, 所述电压控制电路的基准端与功率调整电阻之间连接有基准端调压电阻，所述基准端调压电阻用于调节所述电压控制电路的基准端电压。
实施本发明的LED驱动电路，可使用变压器和TL432芯片或TL431芯片替代现有的较为复杂且昂贵的电源管理IC，从而简化LED驱动电路、降低制造成本。
附图说明
下面将结合附图及实施例对本实用新型作进一步说明，附图中：
图1是本发明LED驱动电路优选实施例的结构方框图；
图2是本发明LED驱动电路优选实施例的电路示意图。
具体实施方式
本发明提供一种LED驱动电路，该LED驱动电路使用变压器、MOS管和电压控制电路（优选现有的TL432芯片或TL431芯片）替代现有的电源管理IC来控制驱动电路。
如图1所示，本发明的LED驱动电路包括变压器、MOS管、功率调整电阻、整流电路、电压控制电路和直流隔离电路，其中，功率调整电阻用于调整整个驱动电路的功率，变压器为双绕组变压器，第一绕组NP的一端连接到现有的外部电源，其所接收的电压即为变压器的输入电压，第二绕组NA的一端接地；电压控制电路包括用于控制MOS管通断的控制端、用于调整控制端电压的基准端、以及接地端，其中控制端和外部电源与MOS管的栅极分别连接，基准端通过功率调整电阻接地，接地端直接接地。在本实施例中，MOS管是N沟道MOS管。
变压器的第一绕组NP的一端与外部电源连接，另一端与MOS管的源极连接， MOS管的漏极通过功率调整电阻接地；变压器的第二绕组NA的一端接地，另一端通过直流隔离电路与MOS管的栅极连接，变压器的第二绕组输出的电压即为变压器的输出电压；变压器的第一绕组NP又通过整流电路与LED负载连接。
在本实施例中，上述的第一绕组NP用于为LED负载供电，第二绕组NA用于为MOS管的电容充电。当第一绕组NP不能为LED负载供电时，第一绕组NP与外部电源连接的一端为正极，与MOS管源极连接的一端为负极，第二绕组NA接地的一端为正极，另一端为负极；当第一绕组NP为LED负载供电时，第一绕组NP与外部电源连接的一端为负极，与MOS管源极连接的一端为正极，第二绕组NA接地的一端为负极，另一端为正极。
整流电路，用于将变压器输向LED负载的交流电转换为直流电。整流电路通常由主电路、滤波器等组成，滤波器接在主电路与负载之间，用于滤除脉动直流电压中的交流成分；主电路多用硅整流二极管和晶闸管组成。在本实施例中，可以用一个整流二极管代替整流电路，整流二极管利用PN结的单向导电特性，把来自第一绕组NP的交流电变成脉动直流电。
MOS管，用于控制变压器与LED负载间电流通断，当MOS管导通时，整流电路截止，变压器与LED负载间为断路，当MOS管截止时，整流电路导通，变压器与LED负载间为通路。
电压控制电路，用于控制MOS管通断，当其控制端电压高于MOS管的阈值电压时，MOS管导通，当其控制端电压低于MOS管的阈值电压时，MOS管截止。电压控制电路为现有的TL432芯片或TL431芯片，本实施例中采用TL432芯片，其阴极C对应控制端，阳极A对应接地端，参考端R对应基准端，TL432芯片的基准电压为1.249V，TL431芯片的基准电压为2.5V。
功率调整电阻，可调节电压控制电路基准端电压，功率调整电阻的电压接近电压控制电路的基准电压时，电压控制电路将其控制端电压调整到低电压状态，MOS管截止。
直流隔离电路，用于防止直流电流入变压器的第二绕组。
具体实现过程中，外部电源输入的电压（外部电源的输出电压即为输入整个驱动电路的电压）从零增加到一个预设固定值，电压控制电路控制端的电压随着输入电压的增加而增加，电压控制电路的控制端为高电压状态，当电压控制电路的控制端电压高于MOS管的阈值电压时， MOS管导通，外部电源输入的电流依次流过变压器的第一绕组、MOS管和功率调整电阻，同时变压器T1储存能量、整流电路截止，变压器与LED负载间为断路；功率调整电阻的电压随着流过功率调整电阻的电流的增加而增加，当功率调整电阻的电压与电压控制电路基准端的电压近似相等时，电压控制电路将控制端调整为低电压状态，MOS管截止，变压器的第二绕组通过直流隔离电路为MOS管的电容充电，同时整流电路导通，变压器的第一绕组通过整流电路向LED负载供电；MOS管的电容上的电压随着变压器的第二绕组的供电不断升高，MOS管的电容上的电压高于MOS管的阈值电压时，MOS管导通，电压控制电路将控制端调整为高电压状态，维持MOS管导通，外部电源输入的电流依次流过变压器的第一绕组、MOS管和功率调整电阻，同时变压器T1储存能量、整流电路截止，变压器与LED负载间为断路。周期重复上述过程，本发明通过电压控制电路和变压器来控制LED驱动电路。
在本发明的优选实施例中，电压控制电路可由TL432芯片或TL431芯片替代；直流隔离电路可由串联的直流隔离电容和直流隔离电阻替代，其中直流隔离电容与变压器的第二绕组连接，直流隔离电阻与MOS管的栅极连接。
在本发明的优选实施例中，上述LED驱动电路还可包括补偿电路，该补偿电路的输入端与电压控制电路的控制端连接，盖补偿电路的输出端与电压控制电路的基准端连接，该补偿电路还可包括串联的补偿电阻和补偿电容。
在本发明的优选实施例中，上述驱动电路还可包括用于防止MOS管击穿的保护电路，该保护电路的输入端与电压控制电路的控制端连接，该保护电路的输出端与电压控制电路的接地端连接，该保护电路还可包括并联的稳压二极管和保护电阻。
在本发明的优选实施例中，电压控制电路的控制端与外部电源之间连接有控制端调压电阻，该调压电阻用于调节电压控制电路的控制端电压。
在本发明的优选实施例中，电压控制电路的基准端与功率调整电阻之间连接有基准端调压电阻，该基准端调压电阻用于调节电压控制电路的基准端电压。
图2是图1所示的本发明LED驱动电路具体实施例的电路图，如图2所示，变压器为T1，其第一绕组NP一端与外部电源连接，另一端与MOS管Q1的源极连接，MOS管的漏极经功率调整电阻R6接地；变压器T1的第二绕组NA一端接地，另一端经直流隔离电容C1和直流隔离电阻R2与MOS管Q1的栅极连接。
电压控制电路为TL432芯片，TL432芯片的阴极C分别与外部电源和MOS管Q1的栅极连接，阴极C与外部电源间连接有控制端调压电阻R1，TL432芯片的阳极A接地，TL432芯片的参考端R通过基准端调压电阻R5和功率调整电阻R6接地。
保护电路为并联的稳压二极管ZD1和保护电阻R4，稳压二极管ZD1和保护电阻R4并联于TL432芯片的阴极C和阳极A。
补偿电路为串联的补偿电阻R3和补偿电容C2，外部电源输入的电流一次流经控制端调压电阻R1、补偿电阻R3、补偿电容C2、基准端调压电阻R5和功率调整电阻R6。
整流电路为整流二极管D1。
LED负载为并联的第三电容C3和四个发光二极管D10-D13。
具体实现过程中，TL432芯片阴极端C的电压随着输入电压Vin的增加而增加，当阴极端C的电压高于MOS管Q1的阈值电压时，MOS管Q1导通，使得输入电流流过变压器T1的第一绕组NP、MOS管Q1和功率调整电阻R6，同时变压器T1储存能量，同时整流二极管D1截止（此时第一绕组NP为上正下负，由第三电容C3给LED负载供电；第二绕组NA为上负下正，不会有电流流过直流隔离电容C1和直流隔离电阻R2）；随着流过功率调整电阻R6的电流增加， R6上面的电压不断增加，当R6的电压接近TL432芯片的基准电压1.249V时，TL432芯片内部将会把阴极段C的电压下拉到低电平，栅极电压低于MOS管Q1的阈值电压，从而MOS管Q1将被关断，此时变压器T1释放能量，第二绕组NA给MOS管Q1的电容充电，同时整流二极管D1导通，第一绕组NP向LED负载供电（NP为上负下正， NA为上正下负，有电流流过直流隔离电容C1和直流隔离电阻R2），当MOS管Q1电容上的电压高于MOS管Q1的阈值电压时，MOS管Q1又重新导通。如此重复以上过程。这样就可以通过TL432芯片和变压器T1来控制LED驱动电路。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的权利要求范围之内。

Claims (20)

  1. 一种LED驱动电路，其中，所述驱动电路包括变压器、MOS管、功率调整电阻、直流隔离电路、整流电路和电压控制电路；
    所述变压器包括第一绕组与第二绕组，所述第一绕组的一端与外部电源连接，另一端与MOS管的源极连接，所述MOS管的漏极通过功率调整电阻接地；所述第二绕组的一端接地，另一端通过直流隔离电路与所述MOS管的栅极连接；
    所述电压控制电路包括用于控制MOS管通断的控制端、用于调整控制端电压的基准端、以及接地端；所述控制端与外部电源和MOS管的栅极连接，所述基准端通过功率调整电阻接地，所述接地端直接接地；
    所述变压器与所述电压控制电路协作控制MOS管的通断，当MOS管导通时，外部电源输入的电流依次流过变压器的第一绕组、MOS管和功率调整电阻，整流电路截止；当MOS管截止时，变压器的第二绕组通过直流隔离电路为MOS管的电容充电，整流电路导通，变压器的第一绕组通过整流电路向LED负载供电。
  2. 根据权利要求1所述的LED驱动电路，其中，所述整流电路为整流二极管。
  3. 根据权利要求1所述的LED驱动电路，其中，所述电压控制电路包括TL432芯片或TL431芯片。
  4. 根据权利要求1所述的LED驱动电路，其中，所述直流隔离电路包括串联的直流隔离电容和直流隔离电阻，所述直流隔离电容与所述变压器的第二绕组连接，所述直流隔离电阻与所述MOS管的栅极连接。
  5. 根据权利要求1所述的LED驱动电路，其中，所述驱动电路包括补偿电路，所述补偿电路的输入端与所述电压控制电路的控制端连接，所述补偿电路的输出端与所述电压控制电路的基准端连接。
  6. 根据权利要求5所述的LED驱动电路，其中，所述补偿电路包括串联的补偿电阻和补偿电容。
  7. 根据权利要求1所述的LED驱动电路，其中，所述驱动电路包括用于防止MOS管击穿的保护电路，所述保护电路的输入端与所述电压控制电路的控制端连接，所述保护电路的输出端与所述电压控制电路的接地端连接。
  8. 根据权利要求7所述的LED驱动电路，其中，所述保护电路包括并联的稳压二极管和保护电阻。
  9. 根据权利要求1所述的LED驱动电路，其中, 所述电压控制电路的控制端与外部电源之间连接有控制端调压电阻，所述控制端调压电阻用于调节所述电压控制电路的控制端电压。
  10. 根据权利要求1所述的LED驱动电路，其中, 所述电压控制电路的基准端与功率调整电阻之间连接有基准端调压电阻，所述基准端调压电阻用于调节所述电压控制电路的基准端电压。
  11. 一种LED驱动电路，其中，所述驱动电路包括变压器、MOS管、功率调整电阻、直流隔离电路、整流电路和电压控制电路；所述MOS管的源极接收变压器的输入电压，所述MOS管的漏极通过功率调整电阻接地；所述MOS管的栅极通过直流隔离电路接收变压器的输出电压；
    所述电压控制电路包括用于控制MOS管通断的控制端、用于调整控制端电压的基准端、以及接地端；所述控制端接收外部电源的输出电压，并与MOS管的栅极连接，所述接地端直接接地，所述基准端通过功率调整电阻接地；
    所述变压器与所述电压控制电路协作控制MOS管的通断，当MOS管导通时，变压器的输入电压在变压器、MOS管和功率调整电阻中形成电流；当MOS管截止时，变压器的输出电压通过变压器、直流隔离电路和MOS管为MOS管的电容充电，同时变压器通过整流电路向LED负载供电。
  12. 根据权利要求11所述的LED驱动电路，其中，所述整流电路为整流二极管。
  13. 根据权利要求11所述的LED驱动电路，其中，所述电压控制电路包括TL432芯片或TL431芯片。
  14. 根据权利要求11所述的LED驱动电路，其中，所述直流隔离电路包括串联的直流隔离电容和直流隔离电阻，所述直流隔离电容接收所述变压器的输出电压。
  15. 根据权利要求11所述的LED驱动电路，其中，所述驱动电路还包括补偿电路，所述补偿电路的输入端接收外部电源的输出电压，所述补偿电路的输出端通过所述功率调整电阻接地。
  16. 根据权利要求15所述的LED驱动电路，其中，所述补偿电路包括串联的补偿电阻和补偿电容。
  17. 根据权利要求11所述的LED驱动电路，其中，所述驱动电路还包括用于防止MOS管击穿的保护电路，所述保护电路的输入端接收外部电源的输出电压，所述保护电路的输出端直接接地。
  18. 根据权利要求17所述的LED驱动电路，其中，所述保护电路包括并联的稳压二极管和保护电阻。
  19. 根据权利要求11所述的LED驱动电路，其中, 所述电压控制电路的控制端通过控制端调压电阻接收外部电源的输出电压，所述控制端调压电阻用于调节所述电压控制电路的控制端电压。
  20. 根据权利要求11所述的LED驱动电路，其中, 所述电压控制电路的基准端与功率调整电阻之间连接有基准端调压电阻，所述基准端调压电阻用于调节所述电压控制电路的基准端电压。
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