New driver ICs from TI

TI's new driver ICs are both targeted at AC-powered lighting applications such as retrofit lamps with support for phase-cut triac-based dimmers. The TPS92070 driver IC targets 6W to 20W applications and can also be used in SSL luminaires such as downlights and wall washers. The IC includes power-factor correction (PFC) providing a power factor greater than 0.8 based on a valley-fill circuit. The IC will automatically disable the PFC circuit if it detects a dimmer ensuring optimized dimming response.


The LM3448 utilizes a step-down buck regulator to provide constant output current to LEDs. The IC is specifically designed for space-constrained and cost-sensitive applications such as integral lamps that require minimal external components. The design can handle 2W to 8W applications with full-range dimming and can be combined with external PFC circuits.


Both of the new products include protection features such as thermal shutdown, under-voltage lockout, current limiting, and protection for LED open circuits. Both also integrate the MOSFETs needed to output the pulse-width modulation (PWM) signal that sets the dimming level for LEDs. The products mark the first announcement in the LED lighting space since TI completed the acquisition of National Semiconductor, establishing clear market leadership in LED driver ICs.


Both of the new TI drivers are available now and both come in 16-pin packages. The LM3448 sells for $1.10 and the TPS92070 sells for $0.75 – both in 1000-unit quantities. And both can be used in 110V or 220V lamp designs.   www.bgocled.com

Bridgelux and Martini provide LED lighting to grocery stores in Italy

Coop grocery stores on the Adriatic Coast in Italy recently installed LED lighting fixtures from Martini Lighting, which are built using Bridgelux Décor LED arrays.


Bridgelux Inc., an LED chip and array provider based in Livermore, California, has developed the Décor line of ultra-high CRI LED arrays in cooperation with Martini Lighting, a division of Martini SpA of Milan, Italy. The arrays are designed to bring ultra-bright solid-state lighting to demanding applications such as retail, hospitality, museum and high-end architectural lighting.


 In fact, Coop retail grocers on the Adriatic Coast of Italy recently replaced incumbent lighting with Martini Lighting fixtures and Décor arrays, delivering an 80 percent decrease in energy consumption while reducing the heat and radiation that contribute to food spoilage.


The project involved the one-to-one replacement of 80-110W halogen fixtures with just-introduced 21W Virgola GM and GEX GM fixtures incorporating new Décor ES   www.bgocled.com 

Cree’s XLamp XP-G LED now delivers 140 lm/W

Cree has announced a new upper level of performance for its XLamp XP-G LEDs, which now deliver up to 140 lm/W in production quantities.
Cree describes its XLamp XP-G LEDs as “the industry’s premier LED optimized for directional lighting, used in a variety of applications from street and area lighting to PAR replacement lamps to high-output flashlights.” Cree also says it is the first LED supplier to publish 10,000 hours of lifetime data, which can allow customers to project TM-21 reported lifetimes greater than 60,000 hours, or nearly seven years.


The cool-white XLamp XP-G provides up to 148 lm and 141 lm/W (for the highest-performing bin), while the outdoor white (4000K) XP-G LED delivers up to 139 lm and 132 lm/W and warm white (3000K) offers up to 122 lm and 116 lm/W, all at 350mA.   www.bgocled.com

Controlling an Arduino with an iPod Touch

Saeki Yoshiyasu uses an iPod Touch’s accelometer to control a LED matrix via an Arduino connected to an ethernet shield.         www.bgocled.com

Christmas Message Display Board using LEDs

Christmas is the festival of lights. There is a new project posted on embedded-lab.com that uses LEDs to display Christmas message. The individual letters of the message are created with 5 mm red LEDs and are controlled through a PIC 16F688 microcontroller. Something you would like to make for your Christmas decoration.      www.bgocled.com

LED's basic terminology VF, IV, WL

LED's basic terminology VF, IV, WL, IR flux conversion between interpretation and
V is the voltage.F is positive.I represents current.R stands for reverse.WL represents the wavelength.

     So: VF forward voltage representative of the general low-power led red, yellow, orange, yellow and green of vf is 1.8-2.4v, pure green, blue, white, vf is 3.0-3.6v. IF is the forward current, low-power generally led the IF is 20mA. IR is a reverse current,
     Generally in the reverse voltage below 5v measured points is less than 10uA (microamps), less than 5uA and 0uA several grades. WL is the wavelength, the wavelength of visible light have separate, different wavelengths corresponding to different colors, such as the red light is usually 615-650nm (nanometers), blue light is usually 450-475nm. Because it is a blue chip + white phosphor modulation, so no wavelengths to measure the color temperature (3000k the following yellowish. 3000k-7000k is white, 7000k more blue).

LED's Vf values ​​mean? It's the size of the LED have any effect?

    vf is the forward voltage of the meaning, but not necessarily larger forward voltage, forward current is greater. You see as long as the recognition of low-power led book value of the above will have a vf, If there is a value, regardless of how much value is vf, (red, yellow, green, orange usually 1.8v-2.4v, white, blue, green generally 3.0v-3.6v). If is 20mA. The two are complementary. Example, two white, one is 3.0v, 20mA, one is 3.4v, 20mA, meaning that the first one lamp, you give it 3.0v voltage, the current flowing through it is normal rated current of 20mA, but the first two lights, you give it 3.4v voltage, the current flowing through it is 20mA.Where Vf and If there is no proportional; but one yellow and one white light ratio, such as the yellow light of the voltage is 2.0v, white lamp voltage is 3.3v, 2.0v Fengyun yellow in the voltage and this pieces of white light in 3.3v voltage current flowing through them is the same, are 20mA, Vf and If here is not proportional. Therefore, only specifically refers to the case of lamps with a Vf and If is absolutely proportional. Whether you use when Vf is, so long as control flow all the lamp current of 20mA on ok


LED basic terminology
Luminous flux (lm): the amount of light to emit visible light per second sum. For example, a 100-watt (w) for bulb produces 1500lm, a 40-watt (w), can produce 3500lm lamp luminous flux. ◇ luminous intensity (cd): in the unit solid angle of light emitted flux, which is the light flux emitted by the selected direction in the space density distribution. Intensity unit is Cantera (cd), also known as candlelight. Such as: 1 issued within a unit solid angle lumens of light called a Cantera (1cd).◇ Brightness: light-emitting diode is a light-emitting device, luminance refers to the unit area of ​​illumination, the unit is: cd / square meter, standard LED drive current of 20mA.

  Color Temperature (k): the absolute temperature (k = ℃ +273.15) K to represent, about a black body heating, the temperature rose to a certain extent, the color gradually from dark red - light red - orange - yellow - yellow - white - blue - changes in blue. When a light source with the same bold colors, we will be bold when the absolute temperature as the light source's color temperature. Such as: When the bold dark red showing the heating temperature is about 550 ℃, the color temperature of 823K.

  Luminous efficiency (lm / w): the luminous flux emitted divided by the light source the power consumed. It is an important indicator to measure light energy.Color (ra): light color rendering of the object itself is called the degree of color. That is, the degree of color fidelity. International Commission on Illumination CIE color rendering index of the sun set at 100. Various types of color rendering index varies. Such as: incandescent ra ≥ 90, fluorescent ra = 60 ∽ 90.

  Viewing Angle: Angle X-axis points (left, right) Y-axis (up, down) when the center axis 1 of the brightness, the brightness of left and right or up and down the shaft 1 / 2, the angle of viewing angle; example 70 ° to Viewing angle refers to the down or left from the center of 35 °.

  Wavelength: two LED wavelengths of light emitted, usually red wavelength 620-660nm, pure green, 520-530nm, the blue 470-480nm, Yellow 580-890nm, yellow 550-570nm, see chromaticity diagram, different given wavelength of light of different colors; mixing two colors of light are also different.

  Quaternary: refers to the ALInGaP four chemical elements produced by the light-emitting diodes, can issue yellow / yellow / orange / red (wavelength 550-630nm) between the light with high brightness, low attenuation characteristics for outdoor light-emitting diodes of the current mainstream products.

  Pure Green / yellow: the traditional green LED is yellow-based, wavelengths from 550-570nm, low price, low brightness, decay fast, manufacturing company in 1994, Japan and Asia to create a pure green (wavelength 520-530nm) price high, high brightness, decay slowly, widely used in outdoor display, these two products have significant differences, the design must be clearly distinguished.

  Single / dual color / full color: primary colors of red / green / blue; if a pixel tube containing these three light-emitting diodes are referred to as full-color display; if only as two-color red + green screen, if only one color such as red or yellow is called monochrome display, monochrome text display to play the content-based, dual-color places text + graphics + animation-based, full-color video broadcast places signal-based.

  Life: refers to the initial value of brightness light-emitting diodes in half the time, has become a half-life, different chips used in different environments have different life.

  Intensity decay curves: a variety of chips under certain conditions (temperature, current) and time intensity curve; this curve can truly understand the characteristics of the chip is good or bad.

  Chip / single lamp / pixel pipes: two LED semiconductor material, said light emitting element chip into a chip package can be lit with the smallest unit, said single lamp; many small lamp assembly irrigation package into a large pieces of plastic pipe Cover with a pixel pipe.

  Point diameter: mean pixel tube diameter.

  Pitch: refers to the two adjacent pixels of the distance between the control center, standard distance between the distinguished point of light = light point diameter × 1.25.

  Visible distance: refers to the distance can be clearly seen in this display shows the contents of the body, this word from the text and display related to the high, simple quick calculation formula: --- last visible distance: 50 × high character height (m) --- farthest visual distance: 200 words, high altitude (m)

  Automatically adjust the brightness: brightness light-emitting diodes as the strength of the environment, but also for their own strength of brightness adjustment, generally to reduce the current approach to achieve the purpose of reducing the brightness.

  Point Density: refers to the number of pixels per square tube.

  Operating temperature: you can display the normal minimum temperature and maximum use temperature.
LED light source compared with conventional light sources

Type of light source efficiency (lm / w) Color Temperature (k) Average Life (hours)Incandescent bulbs 1528001000White British halogen 25 30002000-300070 whole series 8000 general fluorescentThree-color fluorescent full range 10 000 9650-250 full range of 50,000 LED lights



LED explanation of terms, and several optical conversion between

      1 light intensity (brightness) What is the meaning?
A: The light intensity (brightness, I) is defined as: point source of luminous intensity in a certain direction, that is the luminous body in unit time by the amount of light emitted, also referred to as brightness, common units of candles (cd, cd), defined as an international candle made from whale oil candles burning 120 cells per hour, cold (grain) luminosity emitted by a cold frame is equal to 0.0648 g
(2) light intensity (brightness) of the unit?
A: The luminous intensity of common units of candles (cd, cd), the international standard candles (lcd) is defined as an ideal blackbody in platinum freezing point temperature (1769 ℃), the perpendicular to the blackbody (the surface area of ​​1m2) direction of 60 births one of the luminosity, the so-called ideal blackbody radiation rate of an object is equal to 1, the energy absorbed by the object can go all the radiation, so that the temperature has remained constant uniform international standard candles (candela) and the old standard candles (candle) of the exchange relationship To 1candela = 0.981candle
3 What is flux? Flux units?
A: The luminous flux (φ) is defined as: point source or non-point source in a unit time emitted by the energy, which can produce visual person (who can feel the radiation flux) that is known as flux. The unit of luminous flux lumen (abbreviated lm), 1 lm (lumen or lm) is defined as an international standard candles of light in the unit solid angle within the arc by flux, due to the spherical area of ​​4πR2, so that the luminous flux equal to one candle-class luminous flux emitted by the 1/4π, or spherical with 4π, so by definition we can see a cd lumen point source will radiate 4π lumens, that is φ (lm) = 4πI (candlelight), assuming △ Ω is a small three-dimensional arc angle, within the solid angle in △ Ω flux △ φ, then there is △ φ = △ ΩI
4 one foot candle What is the meaning?
A: A foot-candles from a candle is the light source (point source or non-point source) a feet away with the light illumination surface orthogonal, abbreviated as 1ftc (1lm/ft2, lm / ft 2), persquare feet within 1 lumen luminous flux received when the illumination, and 1ftc = 10.76lux
5 one meter candlelight What is the meaning?
A: The one meter away from a candle is a candle light source (point source or non-point source) with one meter of the surface orthogonal light illumination, known as the lux (lux, has written lx), per square kilometers feet within the luminous flux received when the illumination is a lumen (lm / m 2)
6.1lux What is the meaning?
A: Each square of the received flux of 1 lumen when the illumination
7 What is the meaning of illumination?
A: The illuminance (E) is defined as: the object to be units of the exposed area on the acceptance of the flux, or by light irradiation of the objects in the unit time per unit area on the accepted luminosity, units in meters candles or foot-candles ( ftc) that
8 illumination and brightness, What is the relationship between the distance?
A: The intensity and brightness, the distance is the relationship between: E (illumination) = I (brightness) / r2 (distance squared)
9 is the body of the illumination according to the size and what factors?
A: The body according to the luminous intensity of illumination and light and the illuminated body and the distance between the light source, but not with the body color of the illuminated surface is independent of the nature and surface area

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Common electric light sources, lighting and its use

Lighting is to light, changing the distribution of light and the distribution of the light source apparatus to achieve the rational use and the purpose to avoid glare. Light from the electric light and shade (controller) supporting components.
    This section describes the composition of light, classification and selection methods. By learning to cope with the type commonly used in electric light source and the applicable sites, selection and arrangement of lighting requirements understanding.A commonly used power source and its use1. Commonly used electric light
Electric lighting is an important component of electric light, electric light sources currently used for lighting, according to light theory can be divided into two categories.① thermal radiation source by the use of electrical heating conductor emitting radiation, the principle is made, such as incandescent, halogen, etc.② gas-discharge light source is to use the gas discharge (current through the gas in the process known as gas discharge) is made of the principle of light, such as fluorescent lamps, high pressure mercury lamp, high pressure sodium lamp and tube-shaped xenon lights. The source classification is based on high or low pressure gas discharge lamp within the high and low pressure points.
The following table shows the characteristics of lamps used and the applicable site.
NameCharacteristics, for places
IncandescentFeatures: color is good, turn on the lights that light, continuous dimming, simple, inexpensive, but life is short, light efficiency is low. For bedroom, living room, lobby, rooms, shops, restaurants, corridors, meeting rooms and courtyards, etc.
HalogenHas all the characteristics of incandescent lamps for general lighting, luminous efficiency and life than ordinary incandescent lighting to more than double, and small size. For meeting rooms, exhibition hall, living room, commercial lighting, film and television arena, instrumentation, automotive, aircraft and other special lighting
FluorescentCommonly known as fluorescent lamps. Features: High luminous efficiency, long life, high quality light. Suitable for offices, schools, hospitals, shops and residential
Energy-saving lampsFeatures: High luminous efficiency, energy saving
High-pressure mercury lampFeatures: long life, relatively low cost. Usage: road lighting, indoor and outdoor lighting and commercial lighting industry
High pressure sodium lampFeatures: long life, high luminous efficiency, through the fog and strong. Uses: street lighting, flood lighting, square lighting and industrial lighting
MHFeatures: long life, high luminous efficiency, good color. Usage: industrial lighting, urban lighting engineering lighting, commercial lighting, stadium lighting and road lighting
Xenon tubeFeatures: power, hair-efficient, turn on the lights that light. Uses: Square, airports and seaports
2. Selection of electric lightThe luminous efficiency of various power sources are quite different, the gas-discharge light source than the thermal radiation power is much higher luminous efficiency. Selection shall be based on the requirements of lighting, the use of the workplace environment conditions and light source characteristics of rational choice. Under normal circumstances, may be gradually replaced with a gas-discharge light source radiation light source, and the possible use of high efficiency gas-discharge light source.
Second, the shadeShade is to improve the lighting quality is an important attachment, the main role is to shade light emitted flux redistribution, limit light glare, reducing light pollution and the prevention of, protection against mechanical damage and installation of lighting and fixed light source, and light play a role with the decorative.
Third, the lightingThe main function of light source is a reasonable distribution of radiation flux to meet the environmental and operational requirements with light, and does not produce glare screens and serious reflection. Choose lamps, in addition to consideration of environmental light distribution and glare limitation requirements, we must also consider the efficiency of lighting, choose high efficiency lamps.1. Classification of lamps
The lighting in the actual process, the bare light source is unreasonable, or even allowed, because the bare light will produce glare, light can not shine and many need to work surface and waste, resulting in low light efficiency. Therefore, adjusting the projection direction of the light source, effectively saving energy, you must use the appropriate lighting.Lamp according to the following conditions be classified.① Press the light distribution in space can be divided into direct, semi-direct type, diffuse type, semi-indirect and indirect type.② in accordance with the installation of lighting in buildings can be divided into Ceiling type, embedded in the roof type, hanging, wall and movable type and so on.③ Press the need for use of the environment can be divided into moisture-proof, explosion-proof safe, explosion-proof and corrosion resistant type.

2. Selection of lampsSelection of lamps and lighting requirements relating to specific conditions to be taken into account according to the actual. Consider mainly the following points.① with the light option, which is the required indoor lighting illumination, work surface illumination is uniform, with or without glare and so on.② economic benefits, that meet certain indoor illumination circumstances, the electric power consumption, equipment investment and operating costs of consumption should be properly controlled to obtain better value for money.③ Select the lamps should be considered when the ambient conditions, but also consider the shape of the lamp is coordinated with the building.

3. Lighting layoutLighting should be arranged to meet the following requirements.① required illumination.② work surface illumination uniformity.③ light shooting at the appropriate, non-glare, no shadow.④ bulbs installed capacity to a minimum.⑤ easy to maintain.⑥ neat appearance and arrangement in harmony with the architectural space.
 
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