The working principle of the LED light source and light stability

Since 2010, Europe, America, Japan and other advanced countries have started to execute the laws ban incandescent bulbs, the law of the light source is based on the limit of low luminous efficiency formerly. Incandescent bulb is disabled, instead of the light source, including light bulbs, cold cathode tube, LED, etc. But to consider the future such as restrictions on hazardous substances, LED light source will be the best choice. LED light source

working principle and characteristics of light-emitting diodes (leds) are semiconductor materials synthesis diode, is composed of PN interface, when plus forward voltage, electron and hole combined with the release of energy in the form of photons, so with luminescent properties. And the light source close to the millimeter less than PN interface, the wavelength of light depends on the properties of materials have different luminous color, common have red, yellow, green, and blue leds. Light emitting diode luminescence brightness can be working voltage ( Current) To adjust the size of the. In a wide range of working current, the brightness of the light emitting diode is increased as the current increased.

LED lighting brightness stability

the brightness of the light emitting diode varies according to the current size, and made of light-emitting diodes (leds), the voltage and current curve slightly difference, thus the brightness of the LED lighting is often along with the change of supply voltage cannot be stable. In order to maintain the brightness stability is consistent, need led constant current drive to achieve. Constant current driver can make leds work in fixed current mode, thus high brightness stability. Constant current drive also let the leds work for a long time in certain electrical flow, make its maintain a long life.

KaiYu technology T6316 is a constant current drive, it is a has 4 channel constant current led drive, the output current can be in accordance with the external resistance. T6316 has + / - 6% accuracy between electric current and channel plus or minus 3% matching accuracy, can be used to street lamp, tube and other lighting equipment. For energy saving consideration, system design should be considered constant current drive across on 0. Between 5 v ~ 2 v. Jobs with light-emitting diodes (leds) at a constant power flow, the pressure across a slight decline, the change also should be considered in system design. Energy-saving consider

LED lighting LED lighting is energy saving, security, but because of the constant current work consideration, also relative increase of energy consumption, so the lighting system design with low energy consumption as the goal. Mentioned within the pressure drop in the 2 v constant current drive, is to consider the design of the low energy consumption, if the voltage of the power supply system and the combination of light-emitting diodes (leds) pressure drop more than 2 v, should be considered to voltage converter to achieve low energy consumption, but still maintain a constant current working mode. Low-power voltage converter based on switch type work, on the basis of feedback circuit control switch cycle, achieve stable output voltage. But in order to maintain the led constant current working status, is the output current feedback circuit to control the converter switching cycle.

KaiYu T6322 of science and technology is a step-down constant current led driver, the current in accordance with the external resistance, can support up to 1. 5 a output current, plus or minus 5% accuracy of current and high power efficiency ( Low energy consumption) Adjust ability and high electric lines. Figure 1

T6322 and other products that compares the power conversion efficiency. Figure 2 is T6322 compared with other products line adjustment ability, Low current rate of change indicates that the high line adjustment ability) 。

in the current floods the market of LED lighting products, their power input system as two classes: a front-end for AC power input system combined with the current control module, such products including frozen ark article lamp, indoor lamps and lanterns, street lamp, desk lamp, MR16, AR111, etc. Another kind of AC power directly into the system integration of the AC/DC converter and constant current circuit, such products including E27 and GU10 type LED bulb lamp, PAR lamp, T5 and T8LED tubes, etc.

the first kind of power supply design in addition to should choose the better efficiency of front end constant voltage power supply, the back-end constant power control efficiency of the power supply module is used according to its features of better power supply design. Its advantage lies in front of the AC/DC power supply, such as switching power supply, DC adapter, such as constant voltage power supply, can be high selectivity and safety certification scheme, thus reducing the threshold of the design.

the second category of design as a result of the integration of the AC/DC power supply circuit and constant current circuit, it can accord with smaller mechanism design of the space, but from the power factor, power efficiency and safety consideration, design also has some difficulty. Today's market, therefore, such products are rarely achieve high luminous efficiency, high power factor ( > 0. 9) Standard.

the current LED lighting products to achieve high luminous efficiency, to become the next generation of the main light source, the priority is the design of the power supply module, according to different product of lamps and lanterns choosing the right design architecture. In addition, the power supply control IC must also improve the efficiency of power supply, power factor, reliability, and to develop suitable for the demand of LED lighting products.