With its unparalleled technical advantages of energy saving, environmental protection, long life and high controllability, LED has become one of the most promising high-tech in the world in recent years. It officially kicks off the comprehensive replacement of traditional lighting. The innovation of semiconductor lighting technology is changing for 100 years. Traditional lighting history. With the application of LED technology in the field of lighting, LED lighting products have set off a green storm of energy conservation and environmental protection around the world, and have been praised as green lighting products by the industry. Today, with increasing energy consumption, some people even predicted that in the next 10 years, LED lighting products will become the only products to replace traditional lighting fixtures such as high-pressure sodium lamps, incandescent lamps, fluorescent lamps and table lamps. LED lamps need to be popularized, not only need to greatly reduce costs, but also need to solve the problems of energy efficiency and reliability, how to solve these problems, and share the method of designing efficient and reliable LED lamps.
Do not use bipolar power device experts to point out that because bipolar power devices are cheaper than MOSFETs, generally about 2 cents, some designers use bipolar power devices to reduce the cost of LED driving, which will seriously affect the circuit. Reliability, because as the temperature of the LED driver board increases, the effective working range of the bipolar device will shrink rapidly, which will cause the device to malfunction when the temperature rises, thus affecting the reliability of the LED lamp. The correct approach is to use the MOSFET. Devices, MOSFET devices have a much longer lifetime than bipolar devices.
Try not to use electrolytic capacitors. Do you want to use electrolytic capacitors in the LED driver circuit? There are supporters and opponents. Supporters believe that if the temperature of the board can be controlled, the life of the electrolytic capacitor can be extended, for example, the life of 105 degrees is selected. For 8000 hours of high-temperature electrolytic capacitors, according to the current electrolytic capacitor life estimation formula, the temperature is doubled for every 10 degrees decrease in temperature, then it has a working life of 16000 hours in a 95 degree environment and a working life of 32,000 hours in a 85 degree environment. The working life is 64000 hours in a 75 degree environment. If the actual working temperature is lower, the life will be longer! It seems that the selection of high quality electrolytic capacitors has no effect on the life of the driving power supply.
In the input part of the LED driver circuit, electrolytic capacitors can be considered. In fact, PI's LinkSwitch-PH can save electrolytic capacitors. PI's single-stage PFC/constant current design allows designers to eliminate large-capacity capacitors in the output circuit. High-voltage ceramic capacitors can be used instead of electrolytic capacitors to improve reliability. Some people use a 400V electrolytic capacitor in the output when designing two-stage circuits, which will seriously affect the reliability of the circuit. The ceramic circuit of the grade circuit can be used. For industrial applications that do not pay much attention to dimming functions, high temperature environments, and high reliability, it is strongly recommended not to use electrolytic capacitors for design.
Do not use a 600V MOSFET
MOSFETs with a withstand voltage of 600V are relatively cheap. Many people think that the input voltage of LED lamps is generally 220V, so the withstand voltage of 600V is enough, but in many cases the circuit voltage will reach 340V. In the case of surge, the 600V MOSFET is easily broken down. , thus affecting the life of LED lamps, in fact, the choice of 600V MOSFET may save some cost but the cost of the entire board, so the Chinese experts in the porcelain library do not recommend the use of 600V withstand voltage MOSFET, preferably withstand voltage exceeds 700V MOSFET.
Try to use the single-stage architecture circuit Doug to indicate that some LED circuits use a two-stage architecture, PFC (Power Factor Correction) isolated DC/DC converter architecture, which will reduce the efficiency of the circuit.
For example, if the efficiency of the PFC is 95 and the efficiency of the DC/DC section is 88, the overall circuit efficiency will be reduced to 83.6! The PI LinkSwitch-PH device integrates the PFC/CC controller, a 725V MOSFET, and the MOSFET driver to In a single package, the efficiency of the driver circuit is increased to 87! Doug points out that such a device greatly simplifies the board layout design, eliminating up to 25 components used in traditional isolated flyback designs! The omitted components include high voltage. Large capacity electrolytic capacitors and optocouplers. Doug said that the LED-level two-stage architecture is suitable for older drivers that must use a second constant-current drive circuit to enable the PFC to drive LED constant current. These designs are outdated and no longer cost effective, so in most cases it is best to use a single stage design.
UPE plastic,full name UHMWPE (ultra high molecular weight polyethylene) is a kind of thermoplastic engineering plastic with excellent properties of linear structure, with a molecular weight of more than 1.5 million.mainly have ESD UPE SHEET,CONDUCTIVE UPE.
Small density, good wear resistance, self - lubricity, impact resistance, corrosion resistance and so on.
Advantages:
1. Average molecular weight about 5,000,000 to 9,000,000;
2.The best abrasive assistance of all plastics , which 4 times higher than that of nylon 66 or teflon and 6 times higher than that of carbon steel;
3.Extremely high impact stength ,which is twice as high as PC ,5 times as high as ABS,it also retaines high toughness at liquid nitrogen temperature (-196'C);
4.Low friction coefficient ,lubricity is equal to that of Teflon ;
5.The best impact energy absorption value of all plastics ,with very good sound reduction effect ;
6.High chemical stability ,capable of resisting various types of corrosion and organic media within certain temperature and concentration range;
7.Strong adhensive resistance which is only second to Teflon;
8.UHMW-PE Plastic is safe , healthful and non-toxic and be can used in contact with food and drugs ;
9.Low density than any other thermoplastic ;
10.Excellent electrical insulation and static resistance ,good resistance to high energy radiation;
11.Moderate mechanical strength,stiffness and creep-resistant property'
12.Outstanding machining property ,very low water absorption .
Deficiencies:
Compared with other engineering plastics, UHMW-PE Plastic is resistant to heat resistance, stiffness and hardness, but can be improved by means of "filling" and "crosslinking".
From the point ofheat resistance, the melting point of UHMW-PE Plastic is approximately the same (136 ℃) and ordinary polyethylene, but because of its big molecular weight, melt viscosity high, so the processing difficulty is big.
Applications:
Papermaking industry : suction box boards ,scrapper,molding plate ,beating ,gear .
Mining industry : charging barrel ,abrasive and adhensive -resistant back lining for warehouses.
Chemical industry : acid pump ,fliter plate , worm gear ,bearing .
Food industry :packing machinery parts ,bottle guide ,screw .wear plate ,slide away ,stud weld ,roller and other transmission parts.
Tenxile industry : buffer board
Food processing industry : chopping block ,refrigerating plant
Wharf:anti-collision board
Specification: the thickness of UHMW-PE Plastic sheet material can be produced from 0.3mm to 1.9mm, the normal width is 600mm, the width can exceed 1200mm, and the length is not limited.
The thickness of plate can be produced from 2mm to 180mm, the usual specification of 2-10mm is 600mm* 1200mm, and the commonly used specification of 10-180mm is 1200*3080mm. UHMW-PE Plastic can also be customized according to requirements, and the width cannot exceed 1200mm, and the length is not limited.
Color: Black and white, can also be made another color, and the color order is 500KG.
Modified varieties: UHMW-PE Plastic can be added to the Glass Fiber, copper powder, and molybdenum disulfide enhancement plate according to customer's requirements.
Add antistatic agent to the permanent plate, the volume resistance value of 10 to the 6 to 9 power.
Add flame retardant to the flame retardant board from UL 94v-0 to HB combustion grade, and other modification requirements are required to customize various additional properties according to the actual use of the customer.
Product certification: most environmental certification reports and safety reports forraw materials, such as SGS report, CTI report, UL report, MSDS safety information, etc.
UHMW-PE Plastic Sheet,Color UHMWPE Sheet,Antistatic UHMWPE Plastic Sheet,Esd UHMWPE Plastic Sheet
Dongguan Noegem Plastic Products Co.,Ltd , https://www.noegempLastic.com