How to calculate the forward voltage of the hottes

How to calculate the forward voltage of LED? Explain the relevant introduction of the performance parameters of LED in detail, and focus on the working voltage and performance parameters of LED in detail

how to calculate the forward voltage of LED

diodes that emit red, green or yellow light are commonly used. The reverse breakdown voltage of LED is greater than 5 v. Its forward volt ampere characteristic curve is very steep. When it is used, the current limiting resistor must be connected in series to control the current passing through the diode. The current limiting resistance R can be calculated by the following formula:

where e is the power supply voltage, UF is the forward voltage drop of LED, and if is the normal working current of LED. The core of LED is a chip composed of p-type semiconductor and n-type semiconductor. There is a transition layer between p-type semiconductor and n-type semiconductor, which is called PN junction. In the PN junction of some semiconductor materials, the excess energy will be released in the form of light when the injected minority carriers are combined with the majority carriers, so that the electric energy can be directly converted into optical energy

pn junction, it is difficult to inject a few carriers, so it does not emit light. This kind of diode made by using the principle of injection electroluminescence is called light-emitting diode, commonly known as LED. When it is in a positive working state (i.e. a positive voltage is applied at both ends), when the current flows from the LED anode to the cathode, the semiconductor crystal will emit light of different colors from ultraviolet to infrared, and the intensity of the light is related to the current

led voltage range

led (light emitting diode) working voltage varies with manufacturing materials. Generally, gallium arsenide phosphorous material is used for warning and indication between 1.55V and 1.85v; Gallium phosphide material is between 1.85v and 2.15v. This kind of LED has red, green, yellow and orange (two-color LED) light-emitting colors to choose from. Generally, the working current is very small, about 5-10ma (0.005a-0.010a), and the brightness is not very high, so it cannot be used for lighting. The LED used in flashlight is a kind of ultra-high brightness. Its working voltage is high, usually 3.35v---3.65v, and the working current is relatively large. At 30ma---50ma, the brightness is very high. At present, the luminous color is single, which is cold light color. In fact, there are many kinds of LEDs, which have been widely used in civil, industrial, scientific and technological, national defense, aerospace and other fields

with the emergence of new technologies, the new integrated r-led increases the working voltage of ordinary red LED from 1.8v-2.2v to 3v-10v. The working current of yxsensor yx503urc LED is Ma, and the working voltage of blue yxsensor yx503brc LED is also from V

led has small working current, low working voltage, high reliability, long service life, good shock resistance and seismic resistance. The intensity of the current that can be modulated can easily modulate the intensity of luminescence and other advantages that traditional lighting devices do not have, so it can be widely used

performance and application of light emitting diode

it is a kind of semiconductor diode, which can convert electric energy into light energy. Light emitting diodes, like ordinary diodes, are composed of a PN junction and also have single conductivity. When a forward voltage is applied to the LED, the holes injected from the P-region to the N-region and the electrons injected from the N-region to the P-region compound with the electrons in the N-region and the holes in the P-region respectively within a few microns near the PN junction, producing spontaneous emission fluorescence. The energy states of electrons and holes in different semiconductor materials are different. When electrons and holes compound, the energy released is different. The more energy released, the shorter the wavelength of light emitted. Commonly used are diodes that emit red, green or yellow light. The reverse breakdown voltage of LED is greater than 5 v. Its forward volt ampere characteristic curve is very steep. When it is used, the current limiting resistor must be connected in series to control the current passing through the diode. The current limiting resistance R can be calculated by the following formula:

r= (e-uf)/if

where e is the power supply voltage, UF is the forward voltage drop of LED, and if is the normal working current of LED. The core of LED is a chip composed of p-type semiconductor and n-type semiconductor. There is a transition layer between p-type semiconductor and n-type semiconductor, which is called PN junction. In the PN junction of some semiconductor materials, the excess energy will be released in the form of light when the injected minority carriers are combined with the majority carriers, so that the electric energy can be directly converted into optical energy. The PN junction adds a reverse voltage, which makes it difficult to inject a few carriers, so it does not emit light. This kind of diode made by using the principle of injection electroluminescence is called light-emitting diode, commonly known as LED. When it is in a positive working state (i.e. a positive voltage is applied at both ends), when the current flows from the LED anode to the cathode, the semiconductor crystal will emit light of different colors from ultraviolet to infrared, and the intensity of the light is related to the current. The core of LED is a chip composed of p-type semiconductor and n-type semiconductor. There is a transition layer between p-type semiconductor and n-type semiconductor, which is called p-n junction. In the PN junction of some semiconductor materials, the excess energy will be released in the form of light when the injected minority carriers are combined with the majority carriers, so that the electric energy can be directly converted into optical energy. The PN junction adds a reverse voltage, which makes it difficult to inject a few carriers, so it does not emit light. This kind of diode made by using the principle of injection electroluminescence is called light-emitting diode, commonly known as LED. When it is in a positive working state (i.e. a positive voltage is applied at both ends), when the current flows from the LED anode to the cathode, the semiconductor crystal will emit light of different colors from ultraviolet to infrared, and the intensity of the light is related to the current

at first, led was used as the indicating light source of instruments and meters. Later, led with various light colors was widely used in traffic lights and large-area display screens, resulting in good economic and social benefits. Take the 12 inch red traffic light as an example. In the United States, 140 watt incandescent lamps with long life and low luminous efficiency were originally used as light sources, which produced 2000 lumens of white light. After passing through the red filter, the light loss is 90%, leaving only 200 lumens of red light. In the newly designed lamp, Lumileds company adopts 18 red LED light sources, including circuit loss, which consume a total of 14 watts, which can produce the same light effect. Automobile signal lamp is also an important field of LED light source application

for general lighting, people need white light source more. In 1998, white LED was successfully developed. This led is made of Gan chip and yttrium aluminum garnet (YAG) encapsulated together. Gan chip emits blue light（ λ P=465nm, wd=30nm), the YAG phosphor containing ce3+ made by high-temperature sintering emits yellow light after being excited by this blue light, with a peak of 550nm. The blue LED substrate is installed in the bowl shaped reflecting cavity and covered with a thin layer of resin mixed with YAG, about nm. Part of the blue light emitted by the LED substrate is absorbed by the phosphor, and the other part of the blue light is mixed with the yellow light emitted by the phosphor to obtain white light. Now, for ingan/yag white LED, by changing the chemical composition of YAG phosphor and adjusting the thickness of phosphor layer, we can obtain various colors of white light with color temperature K. This method of getting white light through blue LED has the advantages of simple structure, low cost and high technical maturity, so it is used most

in the 1960s, scientific and technological workers developed LED light-emitting diodes based on the principle of semiconductor pn junction light-emitting. The LED developed at that time was made of GaAsP, and its luminous color was red. After nearly 30 years of development, now we are very familiar with LED, which can emit red, orange, yellow, green, blue and other colors. However, the white light LED for lighting has only developed in recent years. Here we introduce the white light LED for lighting to readers

1. The relationship between visible light spectrum and LED white light. As everyone knows, the wavelength range of visible light spectrum is 380nm ~ 760nm, which is seven colors of light that human eyes can feel -- red, orange, yellow, green, green, blue, purple, but these seven colors of light are all monochromatic light. For example, the peak wavelength of red light emitted by LED is 565nm. There is no white light in the spectrum of visible light, because white light is not monochromatic light, but a composite light synthesized by a variety of monochromatic light, just as sunlight is white light synthesized by seven monochromatic light, and the white light in color TV is also synthesized by the three primary colors yellow, green and blue. Therefore, to make the LED emit white light, its spectral characteristics should include the whole visible spectral range. However, it is impossible to manufacture led with this performance under the current process conditions. According to people's research on visible light, the white light visible to human eyes needs at least two kinds of light mixing, that is, the mode of two wavelength luminescence (blue light + yellow light) or three wavelength luminescence (blue light + green light + red light). The above two modes of white light require blue light, so ingesting blue light has become the key technology to produce white light, that is, the "blue light technology" pursued by major LED manufacturing companies at present. At present, there are only a few manufacturers who master the "blue light technology" in the world, so the promotion and application of white LED, especially the promotion of high brightness white LED in China, still has a process

2. Technological structure and white light source of white LED. For general lighting, white LEDs are usually formed in two ways in terms of process structure. The first is to use "blue light technology" to cooperate with phosphors to form white light; The second method is a variety of monochromatic light mixing methods. Both of these methods have successfully produced white light devices. The system of the first method to generate white light is shown in Figure 1, in which the ledgam chip emits blue light（ λ P = 465nm), which is packaged with YAG (yttrium aluminum garnet) phosphor. When the phosphor is excited by blue light, it emits yellow light. As a result, blue light and yellow light mix to form white light (the structure of LED is shown in Figure 2). In the second method, chips with different colors are packaged together, and white light is generated by mixing the colors

3. The application prospect of new light sources for white LED lighting. In order to illustrate the characteristics of white LED, first look at the current status of the lighting source. The luminous efficiency of incandescent lamp and halogen tungsten lamp is 12 ~ 24 lumens/watt; The luminous efficiency of fluorescent lamps and HID lamps is 50 ~ 120 lumens/watt. For white LED: in 1998, the luminous efficiency of white LED was only 5 lumens/watt, and by 1999, it had reached 15 lumens/watt, which was similar to that of ordinary household incandescent lamps. In 2000, the luminous efficiency of white LED had reached 25 lumens/watt, which was similar to that of tungsten halogen lamps. Some companies predict that by 2005, the luminous efficiency of LED will reach 50 lumens/watt, and by 2015, the luminous efficiency of LED is expected to reach 150 ~ 200 lumens/watt. At that time, the working current of white LED can reach amperometric level. Therefore, as mentioned above, the elongation of polymer materials is far better than that of metal, fiber, wood, plate and other materials. It can be seen that it will be possible to develop white LED lighting sources for writers

although incandescent lamps and halogen tungsten lamps for general lighting are cheap, they have low luminous efficiency (the thermal effect of lamps consumes electricity in vain), short service life and heavy maintenance workload. However, if white LED is used for lighting, it not only has high luminous efficiency, but also has a long service life (continuous working time of more than 10000 hours), which requires almost no maintenance. At present, Hella company of Germany has developed aircraft reading lamp with white LED; A street in Canberra, the capital of Australia, has been illuminated with white LEDs; China's urban traffic management lights are also using white led to replace the early traffic order indicator. It can be seen that in the near future, white LED will enter the home to replace the existing lighting

led light source has the advantages of low-voltage power supply, low energy consumption, strong applicability, high stability