High-power white LED light source now the advantages of relatively white Sunburn mainly in size, energy-saving and life on. Currently there is no real market power white light LED chip, the so-called Blu-ray high-power white LED is the core, plus phosphor produces polychromatic light, and blue mixed, the visual sense is white. Phosphor composition according to the proportion of different high-power white light LED products also have different color temperature.
High-power LED products currently more common, there are two, one is single-core (light), only one high power LED chips, one is multi-core.
Single-core products such as the size and weight of possession of a great advantage, get a good spotlight effect, also can produce a uniform pan-ray, so a wide, single high-power LED applications, but the shortcomings of single-core high-power LED is also obviously, because space is limited, single power is not easy to expand and upgrade power to a certain extent, the need for cooling equipment accounted for the majority of LED package space.
Multi-core power products using multiple single-core light, arranged in emitter array, packaged in the same thermal substrate.
The advantage of multi-core easily exceed his power 10W, is due to light an area of disadvantage, it is not easy to achieve focus. Moreover, with greater power, driving the higher demand, many multi-chip LED products require 10V-20V drive voltage and drive current of about 1A.
Below we discuss the single-core, high-power white light LED products, high-power LED relatively large individual differences in general we believe that high-power white LED's forward voltage drop between the 3.0V to 4.0V, the nominal state, 1W of drive current is 350mA, 3W is 700mA-1A, while the 5W is 700mA, to rely on the forward voltage drop close to 7V power upgrade.
High-power LED color temperature and light effects are not fixed values, with the drive current increases, the color temperature will gradually change to warm, and light effect after the current reaches a certain value, will continue to increase as the drive current and continuing lower.
Luminous efficiency started to decrease in the drive current, in fact, very much smaller than the rated current, this time with the highest LED light effect. But now the most high-power LED core issue is how to play to provide the brightness, luminous efficiency of the LED light is not much concern
LED lighting effects can be achieved, a number of reasons depends on external optical components, because high-power LED light source is equivalent to a point the state has greatly enhanced the utilization of external optical device, thereby effectively enhancing the lighting effect.
LED damage form, in addition to such physical damage and reverse breakdown, the main problem is heat, which makes the protection of the LED mainly concentrated in the heat on. If the high-power LED thermal design good, high-power LED even work in more than its rated power of the state, will not be much damage, LED's users to use this super power called "overclocking."
As the heat damage is a cumulative damage will take time, so LED is much higher than the rated short time working in the state, generally does not cause permanent damage. This feature makes the LED average current can be consistent with its rating, but higher than the instantaneous current rating of the pulse current driver.
For high-power LED brightness adjustment, usually by current regulation, but we recommend the use of PWM regulator. As the LED current / flux curves and nonlinear, simply adjust the current and lighting effects can not be linear, while the PWM mode can be linear to better results. LED color temperature also changes with drive current, lower current may be made after the color temperature deviate from the requirements, but as long as the open state PWM current mode to achieve the required color temperature, the final color temperature must also meet the requirements.