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Different from the modern electronics industry, lighting is a very old and traditional industries.About 10000 five years ago, French Lascaux caves in the use of the method of animal fat burning lighting, marked the beginning of human conscious light.In 1879, the American inventor Thomas Edison invented incandescent light bulbs, vacuum, formal human society into the era of electric lighting.

Today, the lighting solution has very diverse.The development of China's lighting industry according to the lighting scheme of time generally can be divided into four stages, the first stage for the first vacuum or inert gas to protect metal heat radiation light illumination, represented by incandescent lamp;The second stage for low pressure gas discharge lighting, such as fluorescent lamps, neon lights, etc.;The third stage for high-strength gas discharge lighting, such as high pressure mercury lamp, high pressure sodium lamp, metal halide lamp, etc.The fourth stage for the semiconductor solid-state lighting, such as LED and OLED.

Incandescent light bulb after, finally because of the increase in photosynthetic efficiency cannot be included in the plans to phase out all countries.Low pressure gas discharge and high intensity gas discharge plan due to the increasing photosynthetic efficiency or has good color rendering, unit lumens low cost advantage has become the mainstream in the lighting in recent years.And the appearance of leds and oleds solid lighting solution will increase the lighting level of mankind to a new stage.Lighting solution process of constant evolution is that people constantly improve the luminous efficiency, improve color rendering, improve the service life of the process, as well as innovation and challenge the limit of human beings.

In the late 1980 s, our country's basic in the stage of incandescent lamp lighting demand.With the development of the electronic components industry, since the early 1990 s, the lighting appearance modelling of lamps and lanterns and light source color diversification, and energy-saving consciousness enhancement, has higher photosynthetic efficiency and light color of the low pressure gas discharge (e.g., fluorescent lamp and energy-saving lamps), such as widely used in families and public places, and high intensity discharge lamp (high pressure mercury lamp, high pressure sodium lamp, etc.) as a result of high photosynthetic efficiency, large power in outdoor lighting (lamps, square) has gained popularity.At the beginning of the 21st century, with the development of semiconductor technology, the environmental protection consciousness enhancement, new light source, energy saving, long life, no pollution of the LED lighting has become a trend.

Electronic technology moves several generation of lighting solution

The first generation of incandescent lamp USES the power frequency power supply, do not need to drive circuit, therefore less reliance on electronic components.Low pressure gas discharge lamp, high strength gas discharge lamp to be driving circuit and LED solutions provide power management, so the driver IC and electronic components are very dependent.And different drive mode also seriously affect the use effect of various kinds of lighting solution.

For the typical low pressure gas discharge lamp, such as fluorescent lamp, traditional drive mode adopts inductance rectifier, obvious problem of stroboscopic and low power factor;In the use of the drive mode of the electronic ballast, not only thoroughly eliminate the stroboscopic, and greatly improve the power factor, prolong the service life of tubes and improve lamp lights, at the same time can also convenient flux adjustment, more than 50% lower the energy consumption of the ballast itself.

During this process, the core and grace wisdom pu many IC manufacturers provide such as IRS2530D, UBA2014 driver IC play an important role.The driver IC to promote the progress of the traditional fluorescent lamp.In recent years, fluorescent lighting and constantly improve the service life, such as philips T5 fluorescent lamp driver circuit, have been able to reach 103 lm/W lights, life of 15000 hours, combined with the fluorescent good color rendering and low cost, these advances greatly improve the competitiveness of the fluorescent lamp, extended the fluorescent lamp life cycle.Separation device also plays an important role, of course, such as delay to start the PTC effectively improve the service life of the fluorescent tube, and polymer PTC is commonly used in electronic rectifier circuit to prevent the tube to activate the rectifier was burned down.

High intensity discharge lamp, such as high pressure sodium lamp and metal halide lamps and lanterns with high ignition voltage (4 ~ 5 kv) and negative resistance characteristics, so need proper power management solutions to work properly, the traditional inductance rectifier can't satisfy the use requirement.Such as the international rectifier company and philips semiconductor company provide good IRS2453D, UAB2032 IC is a better driver module.

LED is a new kind of non-linear volt-ampere characteristic components, higher requirements for driving circuit.Usually want to consider in the process of circuit design, fever heat balance constant current output circuit, drive circuit of the power factor, efficiency, flow and surge of the circuit and electrostatic overvoltage protection requirements.Due to the LED voltage fluctuation will cause the current rapidly changing, and the luminous flux is proportional to the current approach, current instability will directly affect the stability of the luminous intensity, so the LED usually need constant current drive.

The LED section temperature is closely related to the luminous efficiency and temperature, due to the power conversion efficiency is low (around 20%), so prone to problems of higher temperature.In high temperature or ambient temperature on the high side, drive or protection circuit current through the LED it is better to have compensation measures to reduce, in order to reduce the heating power, ensure the LED life.The same surge or electrostatic discharge can damage the LED, the LED light intensity change or scrap directly.

The IC manufacturers, the best method, anson, grace wisdom pu, national semiconductor, Texas instruments and ST microelectronics to launch its own LED driver IC, such as an LED driver circuit design with greater choice.The intervention of these companies to give full play to the potential of the LED, and the solid state lighting fast to the market front.

Developing the future lighting electronics industry support

Completely on high temperature radiation shine of the first generation of lighting source is declining, and can't change the fate of elimination.And low pressure gas discharge lighting developed towards small diameter/high driving voltage, which can save materials, reduce cost, but also can improve the luminous efficiency.As luminescent materials and the continuous improvement of driver IC, make this kind of light photosynthetic efficiency continue to improve, such as T5 integrated photosynthetic efficiency can reach above 100 lm/W, coupled with good color rendering, the characteristics of low cost, 3 ~ 5 years in the field of indoor lighting still has strong vitality.

High intensity gas discharge lighting light source also constantly, such as high pressure sodium lamp and metal halide lamp has started to replace halogen lamp.This kind of light has big power, high colour temperature (in the fog had strong penetrability), the characteristics of high light efficiency (available to more than 120 lm/W), with life can reach more than 10000 hours after driver IC, so lighting/car headlights in the square, and other fields have a competitive advantage.

Solid lighting source theory, energy saving/long life/pollution-free advantages of resistance to shock, but the white LED the luminous efficacy is not prominent (is in commonly 80 ~ 80 lm/W), the energy utilization rate is not high also, conversion rate is around 20%), driver circuit complex/power consumption on the high side, the unit cost of lumen higher shortcoming, therefore widely promoted to need time.But we have seen, in the development process of all lighting light source, LED the photosynthetic efficiency and life span of speed is the fastest, is expected in the next few years of commercial white LED can reach 150 lm/W or higher light efficiency, became the highest photosynthetic efficiency, one of the longest light source in the life.

To give full play to the potential of the LED lamps and lanterns and drive circuit are two indispensable support, and the design of the IC will become the core of the driving circuit.LED as a new type of light source, energy saving, long life, no pollution will become the future trend of the development of lighting industry, the development of semiconductor/electronic components industry will directly lead to the LED chip and drive power supply and line protection devices and other products with the development of the technology.

Practical circuit temperature protection scheme

In the low pressure gas discharge lighting, PTC thermistor components are used in fluorescent electronic rectifier, ensure rectifier not damaged tubes to activate.In the high pressure gas discharge lighting circuit, PTC is often used in power supply module, prevent damage of overload or overheating when the power supply module.For solid light-emitting LED, the temperature is a key factors influencing service life of the LED.

When LED driven by constant voltage mode is easy to generate an electric current is too large or the environment temperature is too high temperature is higher than the design temperature of the LED section, in the design of this series PPTC thermistor can have the effect of limiting current.When a current is too large or too hot in the LED, PPTC resistance can limit current increase and decrease of the LED section temperature, improve the service life of the LED, it is very practical and cheap solution.

Walcott is circuit protection components and circuit protection solutions suppliers, products can be divided for flow protection and overvoltage protection device in both directions.Kurt mainly provide over current/over temperature protection PTC thermistor and PESD electrostatic eliminator, another PESD electrostatic suppressor with leds in parallel, to protect the LED damage by pulse current.Future, walcott company will develop more series of temperature sensitive components, can help fluorescent lamp and LED lighting circuit, such as more accurate according to the working temperature adjust output power or provide circuit protection function, in order to prolong the service life of the light source, to avoid damage in advance.