LED lighting application points over-current protection device

LED with low power consumption, long life, environmental protection and other distinctive features, backlight application field in small size to large size panel backlight after penetration, now for general lighting applications for further expansion, is now in the landscape, architecture, and rapid development in the field of business, automobiles, mobile lighting, etc.

in the face of the many applications of LED lighting, because the market does not form a unified specification, there are a variety of drive solutions, but the change from among them, from the point of view of over-current protection mainly according to the input current to the lamp body can be divided into: dc input and grid ac input the two most basic types, two types of main difference is that driver power supply are ac dc module. , of course, there are a lot of resistance, resistance capacitance step-down, such as low cost solution, there is no EMI rectifier and constant current driver module, but due to the selection of primary side fuse in figure 2 is the same, in the second type here.

for LED lighting the main purpose of the over-current protection has 3:

the first, the purpose of the protection of personal property safety, generally in high input voltage applications often for this purpose to increase protection device.

in the second place, the subsystem with the outside world system partition, if the system instability will affect the safety of the subsystem; Subsystem of the device within the damage on the other hand, such as parallel devices appear short circuit failure mode, or caused by the external factors that the insulation of the security level is destroyed, lead to the internal circuit of short circuit, if there is no fuse action system partition with the outside world and doesn't take effective measures in time, will lead to an external system insurance system action, which will cause the whole power supply system, which will indirectly in important places such as hospital of accidental loss, and it may even cause casualties, so sometimes need to add two fuse on the power input end.

third, protect the important and valuable electronic components or devices. For LED lighting lamps and lanterns, LED lamp bead, the cost of most of the cost of the lamps and lanterns, in the isolation of power driven or a constant current driver circuit, need to drive the output end of the necessary over-current protection.

architecture as a result of the power input, in the selection of over-current protection device has bigger difference concerns:

1, in view of the dc input type DCin selection of fuses, need to pay special attention to the temperature reduction factor parameters of fuse, due to the high power LED the calorific value of relatively large, relatively high in the temperature inside the LED lamp cup, if choose temperature reduction larger fuse will choose bigger current specifications, in the same work flow, the protection of the current specification of the fuse capacity relative to reduce some; Additional DCin position, because the backend will use capacitor filter, will produce larger boot pulse current, so the parts need to pay attention to choose fuse consider pulse condition strictly, otherwise the error option is easy to cause the fuse is turned on, the pulse thrust it is difficult to through a lot of time switch machine experiment and surge current, pulse ability strong resistance in the recommended products.

2, to drive the output of the fuse selection, in pay attention to the fuse temperature reduction factor at the same time, also need to consider the fuse fusing rate index, because the current fluctuation is not big, in the case of a circuit or abnormal invalidation, need to quickly cut off the circuit, to protect the back end LED lamp series, recommend choosing fast on location type and a decrease in temperature to fold the fuse.

the above two kinds of situations have more general market patch low-voltage fuse to choose from, such as AEM technology SolidMatrix fuse ® technology, size from 0402 to 1206, the current specification is 0. 5 to 30 a, fast, fast break, high resistance to pulse, slow, and many other different series, different specifications, different characteristics of products for your engineers to choose.

3, and LED lighting for ac input ACin position, especially the size of the LED ball light bulb need to consider both the fuse problem, also need to consider the withstand voltage value of the fuse. But currently on the market can afford to communicate wide voltage range of fuse volume compared commonly big, there are very few small fuse withstand voltage value of the patch can reach 250 vac, aiming at the application, AEM technology introduced AirMatrixTMAF2 series patch fuses, size 6. 1mm*2. 5mm*2. 2 mm, petite but can withstand voltage 250 vac, at the same time also has a high consistency, low resistance, high resistance to the advantages of pulse power, will bring the engineer new friends application experience.

there are some engineers friends think the fuse is no matter use in negative and zero line of fire in the event of over current can be broken, can play a protective role. Engineers with you friends here to share experience, fuse need to have potential difference on a line, and use only a fuse of the on the ground can cut off the circuit, but after cutting off the entire lighting and the land still has potential, internal short circuit will cause circuit device in the event of danger. So in some outlet can be the countries, such as Germany and China, from a security perspective, to consider in some can reverse thrust is best on the LED lighting lamps and lanterns of LN and fuse.