LED tube power supply design to pay attention to what elements?

At present, LED fluorescent lighting market is more active, LED drive power manufacturers are mainly divided into three major types: the first is to do the development of LED chips or LED lights factory, homeopathic downstream infiltration; the second category is to do the original lighting factory ; The third category is completely new to the factory, they used to do power or other products or new business.

LED fluorescent power supply

LED fluorescent power is a very important LED fluorescent parts, if the choice of improper, LED fluorescent lamp can not play his due performance, and even may not be able to use the normal lighting. The following LED fluorescent lighting power to do some small advice for your reference.

1.LED fluorescent lamp why must the constant flow of it?

LED semiconductor characteristics determine its impact by the environment, such as temperature, LED current will increase; voltage increases, LED current will increase. Long over the rated current work, will greatly shorten the LED life. The LED constant current is in the temperature and voltage and other environmental factors change, to ensure that its working current unchanged.

2.LED fluorescent lamp power supply how to match the light board?

(Such as I> 350mA, V <40V); either the current is too small, the voltage is too high (such as I <350V), the current is too small, the voltage is too high (such as I < 40mA, V> 180V), the result is a serious heat, low efficiency, or the input voltage range is not enough.

In fact, choose a best string and parallel way, plus the voltage and current on each LED is the same, and the power of the effect can play the best performance. The best way is to first communicate with the power supply manufacturers, tailor-made.

3.LED fluorescent power supply current is how much is the most appropriate?

General LED rated working current of 20 milliamperes, and some factories started to use, designed 20 milliamperes, in fact this work under the current fever is very serious, after several comparative tests, designed to 17 ~ 19 milliamperes is the comparison Ideally, the recommended design is 18 milliampere.

4.LED fluorescent lamp power supply voltage is how much?

General LED recommended working voltage is 3.0-3.5V, tested, most of the work in 3.125V, so by 3.125V formula is more reasonable. M lamp beads in series with the total voltage = 3.125 * M.

5.LED lamp board series and parallel with a wide voltage to how wide?

To make the LED fluorescent lamp work in a wide range of input voltage range (full voltage) AC85 ~ 265V, then the light board LED string parallel way is very important. As the current power supply is generally non-isolated step-down power supply, in the requirements of a wide voltage, the output voltage should not exceed 72V, the input voltage range can reach 85 ~ 265V. In other words, the number of series does not exceed 23 strings.

The number of parallel not too much, otherwise the working current is too large, serious heat, recommended as 6 and / 8 and / 12 and. The total current does not exceed 240 milliamperes as well. There is also a wide voltage program, that is, first with the L6561 / 7527 voltage elevation to 400V, and then buck, the equivalent of two switching power supply, the cost of double, this program is not high cost, no market.

6. What is the relationship between the series-parallel connection of PED and the PFC power factor and wide voltage?

Currently there are three kinds of power supply PFC on the market: one is not with PFC dedicated circuit, the PFC is generally around 0.65; one is with a passive PFC circuit, light board well, PFC is generally around 0.92; also With an active active 7527/6561 circuit, the PFC can reach 0.99, but the cost of this solution is twice as expensive as the second option.

So the second program more. For passive PFC circuits: also known as paddle-type PFC circuits, the operating voltage range is half the peak of the AC input voltage. If the input is 180V, the peak is 180 * 1.414 = 254V, half of the peak voltage is 127V, minus the step-down pressure difference of 30V, the maximum output is 90V, so the number of LED lamp beads series up to 28 string.

Therefore, in order to get a relatively large power factor, the number of lamp beads can not be too much, otherwise, it can not meet the requirements of low voltage.

7.LED fluorescent lamp constant current accuracy of the number of the most appropriate?

Some of the power supply on the market of poor current accuracy, like the popular PT4107 / HV9910 / BP2808 / SMD802 program and other constant current program, the error of ± 8% or ± 10%, constant current error is too large. General requirements in ± 3% on it.

According to 3% of the error, 6-way parallel, the error of each road about ± 0.5%, if it is 12-way parallel, each road error of about ± 0.25%, the accuracy is enough. Accuracy is too high, the cost will be greatly increased. And the LED is concerned, 17 milliampere and 17.5 milliampere little effect.

8. Isolated / non-isolated

General isolation power supply such as made 15W, on the LED tube, the transformer size is very large, it is difficult to put in. Especially for the T6 / T8 lamp, almost impossible, so the isolation can only be done in general 15W, more than 15W very little, and the price is very expensive Therefore, the isolation of the price is not high, generally non-isolated accounted for more mainstream, the volume can be done smaller, the minimum can be high 8 mm, in fact, non-isolated security measures done, there is no problem.

9.LED fluorescent power efficiency

Output power (output LED voltage * output current / input power). This parameter is particularly important, if the low efficiency means that a large part of the input power into heat out; if installed in the lamp will produce a very high temperature, coupled with our LED a luminous efficiency than the Dissipation of heat, will be superimposed to produce higher temperatures.

And the life of all the electronic parts inside our power supply will be shortened with the rise in temperature. So that efficiency is the most fundamental factor in determining the power life, the efficiency can not be too low, otherwise consumed in the power of the heat is too large. Generally more than 80% on it, but the efficiency of the matching with the light board connection.

10.LED fluorescent lamp power supply size

Height is the main factor limiting, generally used for T6 tube / T8 size requirements can not be too high height ≤ 9 mm. T10 tube height ≤15 mm. Length can be long, easier to heat.