CN104883782A - LED switch driving circuit with low cost - Google Patents
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Abstract
Description
技术领域technical field
本发明涉及LED驱动电源领域，特别涉及一种低成本的LED开关驱动电路。The invention relates to the field of LED drive power supply, in particular to a low-cost LED switch drive circuit.
背景技术Background technique
随着LED生产成本的下降和发光效率的提高，LED在各种设备中的应用越来越多，如家用、车载和建筑照明等。和传统的照明光源相比，LED具有高可靠性、高发光效率、快速响应等优势。但是，LED对驱动电路提出了更高的要求。不管输入电压如何变化，驱动电源必须输出一个恒定的电流来驱动LED以达到固定的亮度。在很多应用场合，出于照明亮度的调节需要，LED还会有调光的要求。With the decline of LED production costs and the improvement of luminous efficiency, LEDs are increasingly used in various devices, such as household, vehicle and architectural lighting. Compared with traditional lighting sources, LEDs have the advantages of high reliability, high luminous efficiency, and fast response. However, LEDs put forward higher requirements on the driving circuit. No matter how the input voltage changes, the driving power supply must output a constant current to drive the LED to achieve a fixed brightness. In many applications, due to the adjustment of lighting brightness, LEDs also have dimming requirements.
LED调光主要有两种实现途径：线性调节LED电流(模拟调光)或使用PWM开关电路(数字调光)。模拟调光实现电路简单，但是驱动电流的调节会导致LED发光色温的变化。这是由于LED的性质：发光特性随着驱动电流的改变而偏移。对于单色LED来说，其发光波长会改变；对白光LED来说，其发光色温会改变，从而影响照明的体验。而且，模拟调光不能保证高精度的电流调节。驱动电路一般基于串联电阻来检测电流，当调光电流大范围变化时，检测误差难以避免，将降低驱动电流的调节精度。There are two main ways to achieve LED dimming: linearly adjust the LED current (analog dimming) or use a PWM switching circuit (digital dimming). The analog dimming implementation circuit is simple, but the adjustment of the driving current will lead to changes in the color temperature of the LED light. This is due to the nature of LEDs: the luminous characteristics shift as the drive current changes. For monochromatic LEDs, the luminous wavelength will change; for white LEDs, the luminous color temperature will change, thus affecting the lighting experience. Moreover, analog dimming cannot guarantee high-precision current regulation. The driving circuit generally detects the current based on the series resistance. When the dimming current changes in a large range, the detection error is unavoidable, which will reduce the adjustment accuracy of the driving current.
相比模拟调光方式，数字调光具有更多的优点：LED不会产生色温偏移；调光精度高，因为PWM控制精度高；大范围的调光下也不会出现闪烁现象等。数字调光将数字控制信号转换为PWM驱动信号，通过改变脉冲电流的占空比实现调光，如图1所示。数字控制器控制DC/DC恒流源输出方波驱动电流，其脉冲宽度可调，通过对驱动电流脉冲宽度的调制转变为LED灯点亮时间的调制，同时降低了输入功率，到达节能和调光的目的。LED工作于较高的开关频率，由于人的眼睛具有视觉滞后性，不会感觉到光源在调光过程中产生的闪烁现象。数字调光方式尽管性能优越，但是实现电路复杂，需采用昂贵的数字控制器，软件的编程也增加了系统的设计成本。在一些民用家电、手持设备等场合需要设计低成本的PWM开关驱动电路，本专利技术就是基于这样的背景展开研究的。Compared with the analog dimming method, digital dimming has more advantages: LED will not produce color temperature shift; dimming precision is high, because of the high precision of PWM control; there will be no flickering phenomenon under wide-range dimming, etc. Digital dimming converts digital control signals into PWM driving signals, and realizes dimming by changing the duty cycle of the pulse current, as shown in Figure 1. The digital controller controls the DC/DC constant current source to output a square wave drive current, and its pulse width is adjustable. Through the modulation of the pulse width of the drive current, it is transformed into the modulation of the lighting time of the LED lamp. At the same time, the input power is reduced to achieve energy saving and regulation. purpose of light. LEDs work at a relatively high switching frequency. Due to the visual hysteresis of human eyes, they will not feel the flickering phenomenon produced by the light source during the dimming process. Although the digital dimming method has superior performance, the implementation circuit is complicated, and an expensive digital controller is required, and the software programming also increases the design cost of the system. It is necessary to design a low-cost PWM switch drive circuit in some civilian household appliances, handheld devices, etc., and this patented technology is based on such a background.
发明内容Contents of the invention
本发明的目的是设计一种低成本的LED开关驱动电路。The purpose of the present invention is to design a low-cost LED switch driving circuit.
为了实现上述目的，本发明实施例提供了一种LED开关驱动电路，包括一LED导通回路、一输入滤波电路和一PWM控制器，其中：In order to achieve the above object, an embodiment of the present invention provides an LED switch drive circuit, including an LED conduction circuit, an input filter circuit and a PWM controller, wherein:
所述LED导通回路包括电流检测电阻R1、电感L2、LED和续流二极管D1。The LED conduction loop includes a current detection resistor R1, an inductor L2, an LED and a freewheeling diode D1.
所述输入滤波电路包括滤波电感L1和滤波电容C1。The input filter circuit includes a filter inductor L1 and a filter capacitor C1.
所述PWM控制器的1脚接电感L2的一端；所述PWM控制器的2脚和4脚接地；所述PWM控制器的3脚接电容C3的一端。Pin 1 of the PWM controller is connected to one end of the inductor L2; pins 2 and 4 of the PWM controller are grounded; pin 3 of the PWM controller is connected to one end of the capacitor C3.
所述PWM控制器的5脚接电阻R3的一端；所述PWM控制器的6脚接滤波电感L1的一端；所述PWM控制器的8脚接电阻R2的一端。Pin 5 of the PWM controller is connected to one end of the resistor R3; pin 6 of the PWM controller is connected to one end of the filter inductor L1; pin 8 of the PWM controller is connected to one end of the resistor R2.
进一步，所述电流检测电阻R1的一端接PWM控制器的7脚和LED的正极；所述LED的负极接电感L2的一端；所述电感L2的另一端接续流二极管D1的正极。Further, one end of the current detection resistor R1 is connected to pin 7 of the PWM controller and the positive pole of the LED; the negative pole of the LED is connected to one end of the inductor L2; the other end of the inductor L2 is connected to the positive pole of the freewheeling diode D1.
进一步，所述滤波电感L1的一端接输入电源；所述电感L1的另一端接电容C1和续流二极管D1的负极；所述电容C1的另一端接地。Further, one end of the filter inductor L1 is connected to the input power supply; the other end of the inductor L1 is connected to the negative pole of the capacitor C1 and the freewheeling diode D1; the other end of the capacitor C1 is grounded.
进一步，所述续流二极管D1采用肖特基型整流二极管。Further, the freewheeling diode D1 is a Schottky rectifier diode.
进一步，所述电容C3采用高精度电容。Further, the capacitor C3 is a high-precision capacitor.
进一步，所述PWM控制器采用固定频率电源管理芯片。Further, the PWM controller adopts a fixed-frequency power management chip.
进一步，所述PWM控制器采用MC34063实现。Further, the PWM controller is realized by MC34063.
本发明实施例提供了一种LED开关驱动电路。驱动电路由降压稳压器构成，电路工作于电流限制模式，去除了电压反馈环路。和现有技术相比，本发明通过基于低成本的模拟芯片实现了PWM开关驱动模式，具有电路结构简单可靠、成本低等优点。An embodiment of the present invention provides an LED switch driving circuit. The driving circuit is composed of a buck regulator, and the circuit works in a current limiting mode, which eliminates the voltage feedback loop. Compared with the prior art, the present invention realizes the PWM switch driving mode based on the low-cost analog chip, and has the advantages of simple and reliable circuit structure, low cost and the like.
附图说明Description of drawings
为了使本发明的目的、技术方案和优点更加清楚，下面将结合附图对本发明作进一步的详细描述，其中：In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:
图1为现有数字调光技术的电路结构框图；FIG. 1 is a block diagram of a circuit structure of an existing digital dimming technology;
图2为本发明LED开关驱动电路的原理图。Fig. 2 is a schematic diagram of the LED switch driving circuit of the present invention.
具体实施方式Detailed ways
以下结合附图，对本发明所述的方法做进一步的详细说明。The method of the present invention will be further described in detail below in conjunction with the accompanying drawings.
图2为本发明实施例提供的LED开关驱动电路的原理图，如图所示，本发明实施例提供了一种低成本的LED开关驱动电路，包括一LED导通回路、一输入滤波电路和一PWM控制器，其中：Figure 2 is a schematic diagram of the LED switch driving circuit provided by the embodiment of the present invention. As shown in the figure, the embodiment of the present invention provides a low-cost LED switch driving circuit, including an LED conduction circuit, an input filter circuit and a PWM controller, wherein:
所述LED导通回路包括电流检测电阻R1、电感L2、LED和续流二极管D1。The LED conduction loop includes a current detection resistor R1, an inductor L2, an LED and a freewheeling diode D1.
所述输入滤波电路包括滤波电感L1和滤波电容C1。The input filter circuit includes a filter inductor L1 and a filter capacitor C1.
所述PWM控制器的1脚接电感L2的一端；所述PWM控制器的2脚和4脚接地；所述PWM控制器的3脚接电容C3的一端。Pin 1 of the PWM controller is connected to one end of the inductor L2; pins 2 and 4 of the PWM controller are grounded; pin 3 of the PWM controller is connected to one end of the capacitor C3.
所述PWM控制器的5脚接电阻R3的一端；所述PWM控制器的6脚接滤波电感L1的一端；所述PWM控制器的8脚接电阻R2的一端。Pin 5 of the PWM controller is connected to one end of the resistor R3; pin 6 of the PWM controller is connected to one end of the filter inductor L1; pin 8 of the PWM controller is connected to one end of the resistor R2.
进一步，所述电流检测电阻R1的一端接PWM控制器的7脚和LED的正极；所述LED的负极接电感L2的一端；所述电感L2的另一端接续流二极管D1的正极。Further, one end of the current detection resistor R1 is connected to pin 7 of the PWM controller and the positive pole of the LED; the negative pole of the LED is connected to one end of the inductor L2; the other end of the inductor L2 is connected to the positive pole of the freewheeling diode D1.
进一步，所述滤波电感L1的一端接输入电源；所述电感L1的另一端接电容C1和续流二极管D1的负极；所述电容C1的另一端接地。Further, one end of the filter inductor L1 is connected to the input power supply; the other end of the inductor L1 is connected to the negative pole of the capacitor C1 and the freewheeling diode D1; the other end of the capacitor C1 is grounded.
进一步，所述续流二极管D1采用肖特基型整流二极管。Further, the freewheeling diode D1 is a Schottky rectifier diode.
进一步，所述电容C3采用高精度电容。Further, the capacitor C3 is a high-precision capacitor.
进一步，所述PWM控制器采用固定频率电源管理芯片。Further, the PWM controller adopts a fixed-frequency power management chip.
进一步，所述PWM控制器采用MC34063实现。Further, the PWM controller is realized by MC34063.
本发明实施例中的驱动电路由结构简单、成本低的降压稳压器构成，可以实现快速调光的特性。电路的控制器MC34063具有内部开关、电流限制比较器、振荡器等。稳压引脚具有关闭功能，一个超过阀值的电压会关闭电源，而电压降低到阀值以下会开启电源。电源开启时，由于没有电压反馈，控制器工作于电流限制模式。The driving circuit in the embodiment of the present invention is composed of a buck regulator with simple structure and low cost, which can realize the characteristic of fast dimming. The controller MC34063 of the circuit has internal switch, current limit comparator, oscillator and so on. The voltage regulator pin has a shutdown function, a voltage exceeding the threshold will turn off the power supply, and a voltage falling below the threshold will turn on the power supply. When the power is turned on, the controller operates in current limit mode because there is no voltage feedback.
上电时，振荡器生成的启动脉冲引起电源内置三极管开启。输入电压通过电流检测电阻R1、LED灯、电感L2和控制器内置三极管形成闭合回路。当电流增大到电流限制比较器的阀值电平时，比较器关闭电源内置开关；电感L2两端电压反向，续流二极管D1导通，直到电源内置开关在下一个开关周期开启。对于一些精度要求不高的场合，PWM控制器MC34063可以较好地完成调光功能，LED可以轻易地以几百赫兹实现PWM调光。其误差放大器可以提供关闭功能以实现LED调光，电流限制比较器提供了精确和快速的电流设置。On power-up, the start-up pulse generated by the oscillator causes the internal transistor of the power supply to turn on. The input voltage forms a closed loop through the current detection resistor R1, the LED lamp, the inductor L2 and the built-in transistor of the controller. When the current increases to the threshold level of the current limiting comparator, the comparator turns off the built-in switch of the power supply; the voltage across the inductor L2 reverses, and the freewheeling diode D1 conducts until the built-in switch of the power supply turns on in the next switching cycle. For some occasions that do not require high precision, the PWM controller MC34063 can better complete the dimming function, and the LED can easily realize PWM dimming at several hundred Hz. Its error amplifier provides a shutdown function for LED dimming, and a current-limit comparator provides accurate and fast current setting.
以上所述仅为本发明的优选实施例，并不用于限制本发明，显然，本领域的技术人员可以对本发明进行各种改动和变型而不脱离本发明的精神和范围。这样，倘若本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内，则本发明也意图包含这些改动和变型在内。The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101616524A (en) * | 2009-07-29 | 2009-12-30 | 广州复旦奥特科技股份有限公司 | A kind of commercial LED illumination driver |
| CN101674697A (en) * | 2009-09-18 | 2010-03-17 | 陆群 | Miniaturization high power output and separation type driving power supply used by LED bulbs |
| CN101917805A (en) * | 2010-08-09 | 2010-12-15 | 海洋王照明科技股份有限公司 | Led drive circuit |
| CN102651929A (en) * | 2011-02-25 | 2012-08-29 | 海洋王照明科技股份有限公司 | LED (Light-Emitting Diode) driven short-circuit protection circuit |
| US20120235585A1 (en) * | 2009-11-19 | 2012-09-20 | Koninklijke Philips Electronics, N.V. | Method and apparatus selectively determining universal voltage input for solid state light fixtures |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101616524A (en) * | 2009-07-29 | 2009-12-30 | 广州复旦奥特科技股份有限公司 | A kind of commercial LED illumination driver |
| CN101674697A (en) * | 2009-09-18 | 2010-03-17 | 陆群 | Miniaturization high power output and separation type driving power supply used by LED bulbs |
| US20120235585A1 (en) * | 2009-11-19 | 2012-09-20 | Koninklijke Philips Electronics, N.V. | Method and apparatus selectively determining universal voltage input for solid state light fixtures |
| CN101917805A (en) * | 2010-08-09 | 2010-12-15 | 海洋王照明科技股份有限公司 | Led drive circuit |
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Application publication date: 20150902 |