With the development of the led industry, major manufacturers began to turn from miscellaneous. Engineers only need to match the parameters provided by the customer. As for how to match? The following teaches you how to design the lamp.
Now let's take an 18- LED led tube as an example to analyze the design ideas:
Then we take the most commonly used 3528 lamp beads as an example. When the LED lamp was first introduced, because of the relatively large price space, the lamp manufacturers use LED chips with high current consistency and high brightness. The current of this type of chip is usually 20mA. ;
First, calculate the power of a lamp bead: 3528 a lamp bead consists of 1 chip, voltage: 3.2V; (parallel circuit: constant voltage, total current added) if it is a good quality LED chip: single The chip current is 0.02A, then the power of a lamp bead is 0.02A×3=0.06W. But the LED chip in the market is in the actual design: the single chip current is designed to be 0.018A (considering the margin), then a lamp The power of the bead is 0.018A×3.2v=0.0576w.
Second, we must first consider whether the lamp is isolated or not. Power W calculation = voltage V × current A, then we can roughly estimate how many lamp beads to be: 18/0.0576=312.5 is about 312
Third, we assume that it is isolated, the general voltage is less than 36v, that is, 36/3 = 12 strings are not isolated, generally set to 24 strings. 312/12=26 and 312/24=13. In this way, we can initially determine two 12-string 26-isolated and 24-string 13 non-isolated solutions.
Fourth, we can choose the driving scheme according to this: First, for this kind of engineer, you can communicate directly with the driver factory, let them adjust the input power to 18w, and tell them the way of your bead string. If you are facing sales, you can tell the current and voltage of the LED driver output as follows: isolation scheme: voltage V=36vI=0.18*26=470MA non-isolated scheme: voltage V=72vI=0.18*13=235MA
Fifth, it is worth noting that the above is an ideal design, but in practice, we often have to consider a lot in design. For example, in terms of cost, first of all, the number of our lamp beads is 312, when the power of the light board has been 18w, the power of the luminaire must be greater than 18w. Therefore, we must consider the efficiency and pf value of the drive: If the power supply is 18w and the pf value is 0.95, the efficiency is 0.85. Then we will design the pcb board according to the power supply.
The method is as follows: the power of the light board = 18 * 0.85 = 15.3w, the number of equal numbers = 15.3w / 0.0576 = 265.6 is about 266, but considering the 12 strings, we have positioned 264 lights. This is another two options: 12 strings 22 and 24 strings 11 and of course it can be 11 strings 24 and 22 strings 12 and all work as long as the voltage of your isolation is less than 36v. This is also a way of thinking about reverse design. It is generally a combination of the two.
This way your work is basically completed, and the rest is just the light board to open this program.
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