24-04-2010, 08:52 PM
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PRACTICAL TRAINING At Z-LED Light
Presented by:
Anirudh Vyas
SCHOOL OF ELECTRONICS & COMMUNICATION ENGINEERING
JODHPUR ENGINEERING COLLEGE AND RESEARCH CENTRE JODHPUR (RAJ.)
Rajasthan Technical University, Kota.
Light-Emitting Diode
Light-emitting diode
Red, green and blue LEDs of the 5mm type
Type
Passive, optoelectronic
Working principle Electroluminescence
Invented Nick Holonyak Jr. (1962)
Electronic symbol
Pin configuration Anode and Cathode
A light-emitting diode (LED) is an electronic light source. The LED was first invented in Russia in the 1920s, and introduced in America as a practical electronic component in 1962. Oleg Vladimirovich Losev was a radio technician who noticed that diodes used in radio receivers emitted light when current was passed through them.
All early devices emitted low-intensity red light, but modern LEDs are available across the visible, ultraviolet and infra red wavelengths, with very high brightness.
LEDs are based on the semiconductor diode. When the diode is forward biased (switched on), electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the color of the light is determined by the energy gap of the semiconductor. The LED is usually small in area (less than 1 mm2) with integrated optical components to shape its radiation pattern and assist in reflection.
¢ History
1907-Electroluminescence was discovered in by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector.
1920s- Oleg Losev created one of the first LED.
1955-Braunstein observed infrared emission generated by simple diode structures using gallium antimonide (GaSb), GaAs, indium phosphide (InP), and silicon-germanium (SiGe) alloys at room temperature and at 77 kelvin.
1962 -The first practical visible-spectrum (red) LED was developed inby Nick Holonyak Jr., while working at General Electric Company.
1968-Hewlett Packard (HP) introduced LEDs, initially using GaAsP supplied by Monsanto.
1972- Holonyak is seen as the "father of the light-emitting diode".George Craford, a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten.
Internal Structure of LED
The inner workings of an LED
I-V diagram for a diode an LED will begin to emit light when the on-voltage is exceeded. Typical on voltages are 2-3 Volt
What is a Diode
A diode is the simplest sort of semiconductor device. Broadly speaking, a semiconductor is a material with a varying ability to conduct electrical current. Most semiconductors are made of a poor conductor that has had impurities (atoms of another material) added to it. The process of adding impurities is called doping.
In the case of LEDs, the conductor material is typically aluminum-gallium-arsenide (AlGaAs). In pure aluminum-gallium-arsenide, all of the atoms bond perfectly to their neighbors, leaving no free electrons (negatively-charged particles) to conduct electric current. In doped material, additional atoms change the balance, either adding free electrons or creating holes where electrons can go. Either of these additions make the material more conductive.
A semiconductor with extra electrons is called N-type material, since it has extra negatively-charged particles. In N-type material, free electrons move from a negatively-charged area to a positively charged area.
A semiconductor with extra holes is called P-type material, since it effectively has extra positively-charged particles. Electrons can jump from hole to hole, moving from a negatively-charged area to a positively-charged area. As a result, the holes themselves appear to move from a positively-charged area to a negatively-charged area.
A diode comprises a section of N-type material bonded to a section of P-type material, with electrodes on each end. This arrangement conducts electricity in only one direction. When no voltage is applied to the diode, electrons from the N-type material fill holes from the P-type material along the junction between the layers, forming a depletion zone. In a depletion zone, the semiconductor material is returned to its original insulating state -- all of the holes are filled, so there are no free electrons or empty spaces for electrons, and charge can't flow.
At the junction, free electrons from the N-type material fill holes from the P-type material. This creates an insulating layer in the middle of the diode called the depletion zone.
To get rid of the depletion zone, you have to get electrons moving from the N-type area to the P-type area and holes moving in the reverse direction. To do this, you connect the N-type side of the diode to the negative end of a circuit and the P-type side to the positive end. The free electrons in the N-type material are repelled by the negative electrode and drawn to the positive electrode. The holes in the P-type material move the other way. When the voltage difference between the electrodes is high enough, the electrons in the depletion zone are boosted out of their holes and begin moving freely again. The depletion zone disappears, and charge moves across the diode.
When the negative end of the circuit is hooked up to the N-type layer and the positive end is hooked up to P-type layer, electrons and holes start moving and the depletion zone disappears.
If you try to run current the other way, with the P-type side connected to the negative end of the circuit and the N-type side connected to the positive end, current will not flow. The negative electrons in the N-type material are attracted to the positive electrode. The positive holes in the P-type material are attracted to the negative electrode. No current flows across the junction because the holes and the electrons are each moving in the wrong direction. The depletion zone increases. )
When the positive end of the circuit is hooked up to the N-type layer and the negative end is hooked up to the P-type layer, free electrons collect on one end of the diode and holes collect on the other. The depletion zone gets bigger.
The interaction between electrons and holes in this setup has an interesting side effect -- it generates light!
Working of a Light Emitting Diode
Light is a form of energy that can be released by an atom. It is made up of many small particle-like packets that have energy and momentum but no mass. These particles, called photons, are the most basic units of light.
Photons are released as a result of moving electrons. In an atom, electrons move in orbitals around the nucleus. Electrons in different orbitals have different amounts of energy. Generally speaking, electrons with greater energy move in orbitals farther away from the nucleus.
For an electron to jump from a lower orbital to a higher orbital, something has to boost its energy level. Conversely, an electron releases energy when it drops from a higher orbital to a lower one. This energy is released in the form of a photon. A greater energy drop releases a higher-energy photon, which is characterized by a higher frequency.)
As we saw in the last section, free electrons moving across a diode can fall into empty holes from the P-type layer. This involves a drop from the conduction band to a lower orbital, so the electrons release energy in the form of photons. This happens in any diode, but you can only see the photons when the diode is composed of certain material. The atoms in a standard silicon diode, for example, are arranged in such a way that the electron drops a relatively short distance. As a result, the photon's frequency is so low that it is invisible to the human eye -- it is in the infrared portion of the light spectrum. This isn't necessarily a bad thing, of course: Infrared LEDs are ideal for remote controls, among other things.
A light-emitting diode (LED) is a semiconductor device that emits visible light when an electric current passes through it. The light is not particularly bright, but in most LEDs it is monochromatic, occurring at a single wavelength. The output from an LED can range from red (at a wavelength of approximately 700 nanometers) to blue-violet (about 400 nanometers). Some LEDs emit infrared (IR) energy (830 nanometers or longer); such a device is known as an infrared-emitting diode (IRED).
An LED or IRED consists of two elements of processed material called P-type semiconductors and N-type semiconductors. These two elements are placed in direct contact, forming a region called the P-N junction. In this respect, the LED or IRED resembles most other diode types, but there are important differences. The LED or IRED has a transparent package, allowing visible or IR energy to pass through. Also, the LED or IRED has a large PN-junction area whose shape is tailored to the application.
¢ Physics
Like a normal diode, the LED consists of a chip of semiconducting material impregnated, or doped, with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriersâ€electrons and holesâ€flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.
The wavelength of the light emitted, and therefore its color, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a non-radiative transition which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.
LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have made possible the production of devices with ever-shorter wavelengths, producing light in a variety of colors.
LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially GaN/InGaN, also use sapphire substrate.
Most materials used for LED production have very high refractive indices. This means that much light will be reflected back in to the material at the material/air surface interface. Therefore Light extraction in LEDs is an important aspect of LED production, subject to much research and development.
Efficiency and operational parameters
Typical indicator LEDs are designed to operate with no more than 30“60 milliwatts [mW] of electrical power. Around 1999, Philips Lumileds introduced power LEDs capable of continuous use at one watt [W]. These LEDs used much larger semiconductor die sizes to handle the large power inputs. Also, the semiconductor dies were mounted onto metal slugs to allow for heat removal from the LED die.
One of the key advantages of LED-based lighting is its high efficiency, as measured by its light output per unit power input. White LEDs quickly matched and overtook the efficiency of standard incandescent lighting systems. In 2002, Lumileds made five-watt LEDs available with a luminous efficacy of 18“22 lumens per watt [lm/W]. For comparison, a conventional 60“100 W incandescent lightbulb produces around 15 lm/W, and standard fluorescent lights produce up to 100 lm/W. A recurring problem is that efficiency will fall dramatically for increased current. This effect is known as droop and effectively limits the light output of a given LED, increasing heating more than light output for increased current.
In September 2003, a new type of blue LED was demonstrated by the company Cree, Inc. to provide 24 mW at 20 milliamperes [mA]. This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time, and more than four times as efficient as standard incandescents. In 2006 they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Also, Seoul Semiconductor has plans for 135 lm/W by 2007 and 145 lm/W by 2008, which would be approaching an order of magnitude improvement over standard incandescents and better even than standard fluorescents. Nichia Corporation has developed a white LED with luminous efficiency of 150 lm/W at a forward current of 20 mA.
It should be noted that high-power (= 1 W) LEDs are necessary for practical general lighting applications. Typical operating currents for these devices begin at 350 mA. The highest efficiency high-power white LED is claimed by Philips Lumileds Lighting Co. with a luminous efficacy of 115 lm/W (350 mA).
Note that these efficiencies are for the LED chip only, held at low temperature in a lab. In a lighting application, operating at higher temperature and with drive circuit losses, efficiencies are much lower. DOE testing of commercial LED lamps designed to replace incandescent or CFL lamps showed that average efficacy was still about 31 lm/W in 2008 (tested performance ranged from 4 lm/W to 62 lm/W).
Cree issued a press release on November 19, 2008 about a laboratory prototype LED achieving 161 lumens/watt at room temperature. The total output was 173 lumens, and the correlated color temperature was reported to be 4689 K.
Lifetime and failure
Solid state devices such as LEDs are subject to very limited wear and tear if operated at low currents and at low temperatures. Many of the LEDs produced in the 1970s and 1980s are still in service today. Typical lifetimes quoted are 25000 to 100000 hours but heat and current settings can extend or shorten this time significantly.
The most common symptom of LED (and diode laser) failure is the gradual lowering of light output and loss of efficiency. Sudden failures, although rare, can occur as well. Early red LEDs were notable for their short lifetime. With the development of high power LEDs the devices are subjected to higher junction temperatures and higher current densities than traditional devices. This causes stress on the material and may cause early light output degradation. To quantitatively classify lifetime in a standardized manner it has been suggested to use the terms L75 and L50 which is the time it will take a given LED to reach 75% and 50% light output respectively. L50 is equivalent to the half-life of the LED.
Colours and materials
Conventional LEDs are made from a variety of inorganic semiconductor materials, the following table shows the available colors with wavelength range, voltage drop and material:
Color Wavelength [nm] Voltage [V]
Semiconductor Material
Infrared > 760
V < 1.9
Gallium arsenide (GaAs)
Aluminium gallium arsenide (AlGaAs)
Red 610 < < 760 1.63 < V < 2.03 Aluminium gallium arsenide (AlGaAs)
Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Orange 590 < < 610 2.03 < V < 2.10 Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Yellow 570 < < 590 2.10 < V < 2.18 Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP)
Gallium(III) phosphide (GaP)
Green 500 < < 570 1.9[29] < V < 4.0 Indium gallium nitride (InGaN) / Gallium(III) nitride (GaN)
Gallium(III) phosphide (GaP)
Aluminium gallium indium phosphide (AlGaInP)
Aluminium gallium phosphide (AlGaP)
Blue 450 < < 500 2.48 < V < 3.7 Zinc selenide (ZnSe)
Indium gallium nitride (InGaN)
Silicon carbide (SiC) as substrate
Silicon (Si) as substrate †(under development)
Violet 400 < < 450 2.76 < V < 4.0 Indium gallium nitride (InGaN)
Purple multiple types 2.48 < V < 3.7 Dual blue/red LEDs,
blue with red phosphor,
or white with purple plastic
Ultraviolet < 400 3.1 < V < 4.4 diamond ©
Aluminium nitride (AlN)
Aluminium gallium nitride (AlGaN)
Aluminium gallium indium nitride (AlGaInN) †(down to 210 nm)
White Broad spectrum V = 3.5 Blue/UV diode with yellow phosphor
Ultraviolet and blue LEDs
Blue LEDs.
Blue LEDs are based on the wide band gap semiconductors GaN (gallium nitride) and InGaN (indium gallium nitride). They can be added to existing red and green LEDs to produce the impression of white light, though white LEDs today rarely use this principle.
By the late 1990s, blue LEDs had become widely available. They have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative InN-GaN fraction in the InGaN quantum wells, the light emission can be varied from violet to amber. AlGaN aluminium gallium nitride of varying AlN fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of the InGaN-GaN blue/green devices. If the active quantum well layers are GaN, as opposed to alloyed InGaN or AlGaN, the device will emit near-ultraviolet light with wavelengths around 350“370 nm. Green LEDs manufactured from the InGaN-GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems.
White light
There are two primary ways of producing high intensity white-light using LEDs. One is to use individual LEDs that emit three primary colors “ red, green, and blue, and then mix all the colors to produce white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.
Due to metamerism, it is possible to have quite different spectra which appear white.
RGB systems
Combined spectral curves for blue, yellow-green, and high brightness red solid-state semiconductor LEDs. FWHM spectral bandwidth is approximately 24“27 nm for all three colors.
White light can be produced by mixing differently colored light, the most common method is to use red, green and blue (RGB). Hence the method is called multi-colored white LEDs (sometimes referred to as RGB LEDs). Because its mechanism is involved with sophisticated electro-optical design to control the blending and diffusion of different colors, this approach has rarely been used to mass produce white LEDs in the industry. Nevertheless this method is particularly interesting to many researchers and scientists because of the flexibility of mixing different colors. In principle, this mechanism also has higher quantum efficiency in producing white light.
Types of LED
LEDs are produced in a variety of shapes and sizes.The color of the plastic lens is often the same as the actual color of light emitted, but not always. For instance, purple plastic is often used for infrared LEDs, and most blue devices have clear housings..
The Main Types of LEDs
Miniature LEDs
Different sized LEDs. 8 mm, 5 mm and 3 mm, with a wooden match-stick for scale.
Main article: Miniature light-emitting diode
High power LEDs
High power LEDs from Philips Lumileds Lighting Company mounted on a 21 mm star shaped base metal core PCB
High power LEDs (HPLED) can be driven at hundreds of mA (vs. tens of mA for other LEDs), some with more than one ampere of current, and give out large amounts of light. Since overheating is destructive, the HPLEDs must be highly efficient to minimize excess heat; furthermore, they are often mounted on a heat sink to allow for heat dissipation. If the heat from a HPLED is not removed, the device will burn out in seconds.
A single HPLED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.
Some well-known HPLED's in this category are the Lumileds Rebel Led, Osram Opto Semiconductors Golden Dragon and Cree X-lamp.. the XLamp MC-E LED chip emitting Cool White light) and are being sold in lamps intended to replace incandescent, halogen, and even fluorescent style lights as LEDs become more cost competitive.
LEDs have been developed by Seoul Semiconductor that can operate on AC power without the need for a DC converter. For each half cycle part of the LED emits light and part is dark, and this is reversed during the next half cycle. The efficacy of this type of HPLED is typically 40 lm/W. A large number of LED elements in series may be able to operate directly from line voltage.
Chip LED
Part No. : WH108
Size : 1.6*0.8*0.17mm
Features : -WH108 is the world's thinnest high-brightness patented chip-LED at
0.17mm.
- It delivers 240mcd@5mA and features more than two times brighter than
the existing chip-LED.
- Capable of producing the same brightness
at a lower power,which helps extend the
Battery life.
Z-Power LED
Size : Ø 12 mm×6.54 mm
Features : -A single LED package providing
the world's highest brightness of 900 lm
and the efficacy of 90 lm/W
-Ultra slim size, super high luminous efficacy,
and low electricity consumption to replace the conventional bulbs.
Z Power Led P5-II
Part No. : F50360
Size : 6.0*5.0*1.0mm
Features : - Provides Full color
- Using 3 RGB Power Chips
- Suitable for decoration lighting.
Z Power Led Z1
Part No. : WZ10150, NZ10150
Size : 5.0*6.0*1.2mm More
Features : - Ultra-thin package height: 1.2 mm
- Unrestricted radiation : ceramic-based body
with a spacious radiation cavity
- Luminous flux
Warm White (NZ10150): 95 lm max (80 Typ.)
Pure White (WZ10150): 120 lm max (105 Typ.)
Application-specific variations
¢ Flashing LEDs are used as attention seeking indicators without requiring external electronics. Flashing LEDs resemble standard LEDs but they contain an integrated multivibrator circuit inside which causes the LED to flash with a typical period of one second. In diffused lens LEDs this is visible as a small black dot. Most flashing LEDs emit light of a single color, but more sophisticated devices can flash between multiple colors and even fade through a color sequence using RGB color mixing.
Old calculator LED display.
¢ Bi-color LEDs are actually two different LEDs in one case. It consists of two dies connected to the same two leads but in opposite directions. Current flow in one direction produces one color, and current in the opposite direction produces the other color. Alternating the two colors with sufficient frequency causes the appearance of a blended third color. For example, a red/green LED operated in this fashion will color blend to produce a yellow appearance.
¢ Tri-color LEDs are two LEDs in one case, but the two LEDs are connected to separate leads so that the two LEDs can be controlled independently and lit simultaneously. A three-lead arrangement is typical with one common lead (anode or cathode).
¢ RGB LEDs contain red, green and blue emitters, generally using a four-wire connection with one common lead (anode or cathode).
¢ Alphanumeric LED displays are available in seven-segment and starburst format. Seven-segment displays handle all numbers and a limited set of letters. Starburst displays can display all letters. Seven-segment LED displays were in widespread use in the 1970s and 1980s, but increasing use of liquid crystal displays, with their lower power consumption and greater display flexibility, has reduced the popularity of numeric and alphanumeric LED displays.
Considerations for use
Power sources
Main article: LED power sources
The current/voltage characteristics of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation). This means that a small change in voltage can lead to a large change in current. If the maximum voltage rating is exceeded by a small amount the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is therefore to use constant current power supplies, or driving the LED at a voltage much below the maximum rating. Since most household power sources (batteries, mains) are not constant current sources, most LED fixtures must include a power converter.
Electrical polarity
Main article: Electrical polarity of LEDs
As with all diodes, current flows easily from p-type to n-type material.[48] However, no current flows and no light is produced if a small voltage is applied in the reverse direction. If the reverse voltage becomes large enough to exceed the breakdown voltage, a large current flows and the LED may be damaged.
Light emitting diodes, commonly called LEDs, are real unsung heroes in the electronics world. They do dozens of different jobs and are found in all kinds of devices. Among other things, they form the numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.
Basically, LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor.
ImageGallery
Light emitting diodes form the numbers on digital clocks, send data from remote controls and light up traffic signals. See more solid state electronics pictures.
Advantages
¢ Efficiency: LEDs produce more light per watt than incandescent bulbs.
¢ Color: LEDs can emit light of an intended color without the use of color filters that traditional lighting methods require. This is more efficient and can lower initial costs.
¢ Size: LEDs can be very small (smaller than 2 mm) and are easily populated onto printed circuit boards.
¢ On/Off time: LEDs light up very quickly. A typical red indicator LED will achieve full brightness in microseconds. LEDs used in communications devices can have even faster response times.
¢ Cycling: LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
¢ Dimming: LEDs can very easily be dimmed either by Pulse-width modulation or lowering the forward current.
¢ Cool light: In contrast to most light sources, LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics. Wasted energy is dispersed as heat through the base of the LED.
¢ Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt burn-out of incandescent bulbs.
¢ Lifetime: LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life, though time to complete failure may be longer.Fluorescent tubes typically are rated at about 10,000 to 15,000 hours, depending partly on the conditions of use, and incandescent light bulbs at 1,000“2,000 hours.
¢ Shock resistance: LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile.
¢ Focus: The solid package of the LED can be designed to focus its light. Incandescent and fluorescent sources often require an external reflector to collect light and direct it in a usable manner.
¢ Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.
Disadvantages
¢ High initial price.
¢ Temperature dependence
¢ Light quality
Constant-Current LED Drivers
LEDs are current-driven devices that require current limiting when driven from a voltage source. In most applications,it is desirable to drive LEDs with a constant-current source.
The current source is used to regulate the current through the LED regardless of power supply (voltage) variations or changes in forward voltage drops, VF , between LEDs.
The devices also allow the user to set the magnitude of constant current to the LEDs. Once set, the current remains constant, regardless of the LED voltage variation, supply voltage variation, or other circuit parameters that could otherwise affect LED current. The output current is controlled by a current mirror, a bandgap regulator, and an external current-control resistor
LED Driver 3W, 350mA
Up to 3 PowerLEDs can be connected on this LED Driver with strain-relief. The driver supplies a constant current of 350mA and is also suitable for using outside of lights. The LED Driver is ENEC and KEMA certificated, short-circuit-proof, suitable for the direct mounting on a normally inflammable area and it has a temperature overload protection over 110°.
Only suitable for indoor.
3W LED DRIVER BOARD
Technical Specifications:
Input voltage: 230V~
Output current: 350mA
Output power: max 3W
Protection class: two
Length: 5.5 cm
Width: 4 cm
Height: 2 cm
Weight: 0.050kg
Caution: The installation and assembly of electrical. equipment may only be performed by a skilled electrician.
Suitable accessories-Eurostecker with supply line
Connection Plug Board 350 mA
TOP SWITCH
Description
TOPSwitch-GX uses the same proven topology as TOPSwitch, cost effectively integrating the high voltage power MOSFET, PWM control, fault protection and other control circuitry onto a single CMOS chip. Many new functions are integrated to reduce system cost and improve design flexibility, performance and energy efficiency. Depending on package type, either 1 or 3 additional pins over the TOPSwitch standard DRAIN, SOURCE and CONTROL terminals allow the following functions: line sensing (OV/UV, line feedforward/ DCMAX reduction), accurate externally set current limit,remote ON/OFF, synchronization to an external lower frequency, and frequency selection (132 kHz/66 kHz).
TOPSwitch-GX Family Functional Description
Like TOPSwitch, TOPSwitch-GX is an integrated switched mode power supply chip that converts a current at the control input to a duty cycle at the open drain output of a high voltage power MOSFET. During normal operation the duty cycle of the power MOSFET decreases linearly with increasing CONTROL pin current Three terminals, FREQUENCY, LINE-SENSE, and EXTERNAL CURRENT LIMIT (available in Y, R or F package) or one terminal MULTI-FUNCTION (available in P or G package) have been added to implement some of the new functions. These terminals can be connected to the SOURCE pin to operate the TOPSwitch-GX in a TOPSwitch-like three terminal mode.
Pin Functional Description
¢ DRAIN (D) Pin:
High voltage power MOSFET drain output. The internal start-up bias current is drawn from this pin through a switched high-voltage current source. Internal current limit sense point for drain current.
¢ CONTROL © Pin:
Error amplifier and feedback current input pin for duty cycle control. Internal shunt regulator connection to provide internal bias current during normal operation. It is also used as the connection point for the supply bypass and auto-restart/ compensation capacitor.
¢ LINE-SENSE (L) Pin: (Y, R or F package only)
Input pin for OV, UV, line feed forward with DCMAX reduction, remote ON/OFF and synchronization. A connection to SOURCE pin disables all functions on this pin.
¢ EXTERNAL CURRENT LIMIT (X) Pin: (Y, R or F package only)
Input pin for external current limit adjustment, remote ON/OFF, and synchronization. A connection to SOURCE pin disables all functions on this pin.
¢ MULTI-FUNCTION (M) Pin: (P or G package only)
This pin combines the functions of the LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) pins of the Y package into one pin. Input pin for OV, UV, line feed forward with DCMAX reduction, external current limit adjustment, remote ON/OFF and synchronization. A connection to SOURCE pin disables all functions on this pin and makes TOPSwitch-GX operate in simple three terminal mode (like TOPSwitch-II).
¢ FREQUENCY (F) Pin: (Y, R or F package only)
Input pin for selecting switching frequency: 132 kHz if connected to SOURCE pin and 66 kHz if connected to CONTROL pin. The switching frequency is internally set for fixed 132 kHz operation in P and G packages.
¢ SOURCE (S) Pin:
Output MOSFET source connection for high voltage power return. Primary side control circuit common and reference point.
Typical Flyback Application
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Z1WF 0-50mm |-40mm H-51mm Z1WM 0-56mm | 1-47 H-45mm
Z3WF 0-76mm |-65mm H-46mm Z3WM Out-88mm In-76mm H-5mm
Z6W 0-12.7mm |-116mm H-53mm Z9WF 0-76mm |-65mm H-105mm
Z12W 0-180mm |-156mm H-113mm SM1WA
Drivers
Z3WD-350ma 12V
Z6WD-350ma 19.5V
Z9WD-500ma 12V
Z16WD-350ma 56V
Z36WD-700ma 56V
ZMR 16C3W ZMR 16C9W 8/25/140
MR16Lens 25 MR16Lens 8 MR16Lens 40 All Types of MCB PCB/Heat Shields
TinySwitch-PK - Power Integrations
Power Integrations introduced the TinySwitch-PK power supply control IC with peak power mode. The new Power Supply Control chip is able to deliver up to 280% peak
power for short periods of time. This feature enables designers to specify transformers rated for the continuous power level
Functional Block Diagram
Description
TinySwitch-PK incorporates a 700 V MOSFET, oscillator, high- voltage switched current source, current limit (user selectable), and thermal shutdown circuitry. A unique peak mode feature boosts current limit and frequency for peak load conditions. The boosted current limit provides the peak output power while the increased peak mode frequency ensures the transformer can be sized for continuous load conditions rather than peak power demands.
Typical Standby Application.
Special Feature
Automatically enters into a special peak mode - doubling operating frequency and boosting current limit for the duration of the peak power requirement - TinySwitch-PK
Power Supply Control IC coaxes up to 280 percent of the design power level out of the same transformer and integrated MOSFET. The challenge in these systems is to design a power supply that can provide the necessary peaks when needed, but does not burden the application with peak costs.
Features and benefits of TinySwitch-PK Power Supply Control IC includes:
¢ Lowest System Cost with Enhanced Flexibility
¢ Simple ON/OFF control, no loop compensation needed
¢ Unique Peak Mode feature extends power range without increasing transformer size
¢ Maximum frequency and current limit boosted at peak loads
¢ Selectable current limit through BP/M capacitor value Higher current limit further extends maximum power in open frame applications
¢ Lower current limit improves efficiency in enclosed adapter applications
¢ Allows optimum TinySwitch-PK choice by swapping devices with no other circuit redesign
¢ Tight I2f parameter tolerance reduces system cost:
¢ Auto-restart delivers <3% maximum power in short circuit and open loop fault conditions
¢ Energy Efficient
¢ selectable current limits, allowing the designer to choose any of three current limit values for each family member without any additional IC pins or external components.
¢ Enhanced Safety and Reliability Features
¢ Very low component count enhances reliability and enables single sided printed circuit board layout
¢ excellent transient load response
¢ High bandwidth
Daily Applications
¢ Traffic Lights
¢ Cars
LED daytime running lights of Audi A4
Western Australia Police car using LED
¢ House Lighting
LED Tube Lights
LED Christmas Lights
¢ Non-visual applications
LED panel light source used in an experiment on plant growth. The findings of such experiments may be used to grow food in space on long duration missions
The light from LEDs can be modulated very fast so they are extensively used in optical fiber and Free Space Optics communications. This include remote controls, such as for TVs and VCRs.
Light can be used to transmit broadband data
¢ LED Disco Lights
A large LED display behind a disc jockey.
Other Applications
¢ exit signs
¢ emergency vehicle lighting
¢ LED-based Christmas lights
¢ high-mounted brake lights
¢ Dropped ceiling with LED lamps
¢ backlighting for LCD
Interesting Facts about LED
¢ A 13 watt LED lamp produces 450 to 650 lumens [63]. which is equivalent to a standard 40 watt incandescent bulb [64]. A standard 40 W incandescent bulb has an expected lifespan of 1,000 hours while an LED can continue to operate with reduced efficiency for more than 50,000 hours, 50 times
¢ A single kilowatt-hour of electricity will generate 610 g of CO2 emissions.[65] Assuming the average light bulb is on for 10 hours a day, a single 40-watt incandescent bulb will generate 89 kg of CO2 every year. The 13W LED equivalent will only be responsible for 29 kg of CO2 over the same time span. A building™s carbon footprint from lighting can be reduced by 68% by exchanging all incandescent bulbs for new LEDs.
¢ the average incandescent mini-light uses 5 watts per bulb. An entire string of LED mini-lights uses around 4 watts... Yeah, I said the entire string! Do the math on that one."
¢ Regular" incandescent Christmas light bulbs may lose their life after about 1,800 hours, whereas LED Christmas light bulbs will still be twinkling long after 4,000 hours. That's about 7 months of continuous testing!
Index
1) Light Emitting Diode¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.5
a) History¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..6
b) Internal Structure¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦....7
c) Inner Working of LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...7
2) What is Diode..........................................................................................8
a) Physics¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦11
3) Efficiency &Operational Parameters¦¦¦¦¦¦¦¦¦¦¦¦¦..12
4) Lifetime & Failure¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...14
5) Colours & Materials¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.14
6) UV Blue LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..16
7) White Light¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..17
8) RGB System¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦....17
9) Types Of LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....18
a) Miniature LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....19
b) High Power LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.19
c) Chip LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....20
d) Z-Power LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.......21
e) Z-PowerLED P5II¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...21.
f) Z-Power LED Z1¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....22
10) Application & Specific Variations¦¦¦¦¦¦¦¦¦¦¦¦........22
a) Considerations for use¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....23
11) Advantages¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦........25
12) Disadvantages¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...26
13) Constant Current LED Driver¦¦¦¦¦¦¦¦¦¦¦¦¦.¦....26
a) LED Driver 3W-350mA¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.....27
14) Technical Specifications¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..28
15) Top Switch¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...28
a) Description¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦..28
b) Top Switch-GX Family Description¦¦¦¦¦¦¦¦¦¦¦.......29
c) Functional Block Diagram ( Y,R or F package )¦¦¦¦¦¦¦..30
d) Functional Block Diagram P or G package¦¦¦¦¦¦.............31
e) Pin Functional Description¦¦¦¦¦¦¦¦¦¦¦¦¦¦........32
f) Typical Flyback Application¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...33
16) Product related to LED & LED Driver¦¦¦¦¦¦¦¦¦¦...........33
17) Tiny Switch-PK-Power Integrations¦¦¦¦¦¦¦¦¦¦¦¦¦....36
a) Functional Block Diagram¦¦¦¦¦¦¦¦¦¦¦¦¦¦.........36
b) Description¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.......37
c) Typical Standby Application¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦....37
d) Special Features¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦...37
e) Features & Benefits of Tiny Switch-PK-Power
Supply Control IC¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦38
18) Daily Applications¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦¦.........39
19) Interesting Facts about LED¦¦¦¦¦¦¦¦¦¦¦¦¦¦............43
