It is observed that in 2014, whether it is household LED lighting, road LED lighting or commercial LED lighting, there is a full-scale outbreak. Since each higher quality LED lighting fixture must basically be equipped with overcurrent, overvoltage protection components (such as fuses and MOVs) and EMI filter components, the need for peripheral protection components such as overcurrent and overvoltage and EMI filtering is also rising. .
Bharat Shenoy, director of technology marketing for Littelfuse's Electronic Business Development Division, said that demand for MOVs and fuses with high surge tolerance will be bullish for the LED lighting market in 2014. Fuses with high surge tolerance will also be used in the growing wireless base station infrastructure market. In addition, low-impedance, high-current PTCs will be used in mobile computing lithium-ion battery protection applications, and this market will grow with smartphones and tablets.
He pointed out that the TMOV25 thermal protection varistor and 477 series fuse developed for the outdoor LED lighting market are Littelfuse's most competitive products. The 688 series and 328 series high surge withstand fuses are mainly used in wireless base station infrastructure applications. The Lo-Rho series of PTCs are primarily targeted at lithium-ion battery applications.
Currently, the longest lead time for TMOV25 is 8-10 weeks, BharatShenoy said: We will try to shorten the delivery cycle by 2 weeks, which is 6-8 weeks.
The fuse will replace the PTC as the main overcurrent protection component. The AC input of each outdoor LED lighting fixture must be equipped with an overcurrent protection component to prevent the inrush current induced by the power line during lightning strikes from damaging the rectifier diode and The electronic components behind. Although the front of the overcurrent protection component must be equipped with one or several lightning protection components (such as MOV, GDT, TVS or semiconductor discharge tubes), these lightning protection components will discharge most of the lightning surge current, but there will still be some It will flow through the overcurrent protection component to the back electronic components. Therefore, the overcurrent protection component must be able to withstand high surge currents. This surge withstand capability is very important because the overcurrent protection component cannot be blown when the lightning surge current comes.
Considering that the self-recovering PTC cannot withstand high currents, this overcurrent protection component can only select a fuse. And in order to ensure that the fuse can withstand lightning surge current, this position requires the use of a fuse with sufficient i2t or time difference. In addition, considering the fluctuations or tolerances of AC mains, the typical rated withstand voltage of this fuse needs to be as high as 300Vac.
Bharat Shenoy, director of technology marketing at Littelfuse's Electronic Business Development Unit, said: The best overcurrent protection option for outdoor LED lighting is the fuse. We recommend 807 or 407 series fuses for outdoor LED lighting applications, especially for road lighting applications.
MOV provides the lowest level of lightning surge protection. General outdoor LED lighting driver power supply AC input will be equipped with a MOV (varistor) for lightning overvoltage protection, which provides a minimum level of lightning surge protection. However, Bharat Shenoy said: For highly exposed outdoor LED lighting applications, we recommend that customers use a lightning surge protection module that is installed at the power input of an outdoor LED lighting fixture.
Typically, this is a replaceable surge arrester module with several thermal protection MOVs configured in line neutral, one MOV protection mode. Sometimes a GDT will be placed on the common ground to prevent degraded MOV-induced drain to the ground. In addition, BharatShenoy highly recommends that customers place a TVS diode on the DC side of the diode bridge as a further protection for sensitive LED drivers.
In the past three years, PLED shipments have exceeded 50 million PLEDs. Actually, it is a current bypass diode. When the LED connected in parallel with it works normally, the PLED remains open and the system does not feel it. However, when the LED connected in parallel with it opens for various reasons, the PLED is turned on and enters the working state.
Since outdoor LED lighting fixtures usually require a very high power, such as 120W, and a single LED power usually does not exceed 3W, outdoor LED lighting fixtures usually consist of a large number of LEDs combined in series, in order to prevent each LED string from being An LED is open and the LEDs on the entire string are not working properly. Therefore, high-reliability outdoor LED lighting fixtures must have one PLED in parallel with one or several LEDs on each string.
When one or more PLED products connected in parallel on the LED string are excited, the LED driver will try to maintain a constant drive current even if the voltage of the LED string becomes lower because the voltage of the PLED in the on state is higher than that of a typical LED. To be low.
At present, the suppliers that can provide LED bypass diodes and enjoy high reputation are Bourns and Littelfuse. Littelfuse has the most complete PLED product line, which can protect 1W, 2W and 3W LEDs in the smallest package size on the market. In addition, Littelfuse can also provide the industry's lowest thermal resistance PLED products, which can also achieve the highest performance at high ambient temperatures (especially for outdoor LED lighting).
ChadMarak, Director of Technology Marketing, Littelfuse Semiconductor Business Unit, said: In 2012, our PLED products have been sold directly or indirectly to more than 600 different customers, and in the past 2-3 years, PLED products have shipped more than 5,000. Ten thousand.
Although it seems that PLED has led to an increase in the cost of outdoor LED lighting BOM, it also effectively reduces the customer's product maintenance costs. ChadMarak pointed out: Our customers are very satisfied with the reliability of our products, especially those that need to ensure personal safety. In addition, our products have helped customers reduce maintenance costs, and even if one or two LEDs fail, the entire string of LEDs will remain lit.
Most importantly, ChadMarak stated that our leading position in the market allows us to offer differentiated solutions such as PLEDxSW, which uses a white molding compound to reduce light absorption and ensure optimal optical illumination performance.
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