The most widely used lighting fixtures in commercial offices today are LED fluorescent tubes. Whether an LED fluorescent tube can work perfectly depends on the quality of its own lamps and the appropriate driving power supply. If the power is not selected properly, the LED fluorescent tube may not work properly. At present, the LED fluorescent lamp lighting market is relatively active, and LED drive power manufacturers are mainly divided into 3 types:

The first type is the factory that develops LED chips or LED lights, which penetrates into the downstream;

The second type is the factory that was originally used for general lighting;

The third category is completely new factories, they used to do power or other products or start a new business.

Now Baite Lighting introduces the ten characteristics of some LED fluorescent tube power supplies.

1. Why must the LED fluorescent lamp power supply be constant current?

The characteristics of LED semiconductors determine that they are greatly affected by the environment. For example, the temperature of the LED will increase the current of the LED; the increase of the voltage will increase the current of the LED.

Working longer than the rated current for a long time will greatly shorten the service life of the LED. The constant current of LED is to ensure that its working current does not change when environmental factors such as temperature and voltage change.

2, how can the LED fluorescent lamp power supply match the lamp?

Some customers design the lamp board first, and then find the power supply, and find it difficult to have a suitable power supply, either the current is too large and the voltage is too small (such as I> 350mA, V <40V); 40mA, V> 180V), the result is severe fever, low efficiency, or insufficient input voltage range.

In fact, choose the best serial and parallel connection method, the voltage and current applied to each LED are the same, but the effect of the power supply can play the best performance. The best way is to communicate with the power supply manufacturer first, tailor-made.

3. What is the most suitable working current for the LED fluorescent lamp power supply?

Generally, the rated operating current of LED is 20 milliamps. Some factories run out of it at the beginning. The design is 20 milliamps. In fact, the working heat is very serious at this current. After many comparative tests, the design is 17-19 milliamps. Ideally, the recommended design is 18 mA.

4.What is the working voltage of the LED fluorescent lamp power supply?

The recommended working voltage for general LEDs is 3.0-3.5V. After testing, most of them work at 3.125V, so the calculation formula based on 3.125V is more reasonable. The total voltage of M lamp beads connected in series = 3.125 * M.

5, how wide is the series and parallel and wide voltage of the LED lamp board?

In order to make the LED fluorescent lamp work in a wide input voltage range (full voltage) AC85 ～ 265V, the LED series and parallel mode of the lamp board is very important.

As the current power supply is generally a non-isolated step-down power supply, when a wide voltage is required, the output voltage should not exceed 72V, and the input voltage range can reach 85 ~ 265V. That is, the number of concatenations does not exceed 23 strings.

Do not connect too many in parallel, otherwise the working current is too large and the fever is serious. It is recommended to be 6 and / 8 and / 12. The total current does not exceed 240 mA.

There is also a wide voltage solution, which is to first increase the voltage to 400V with L6561 / 7527, and then step down, which is equivalent to two switching power supplies, which is twice as expensive. This solution is not cost-effective and there is no market.

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

There are three cases of power supply PFC on the market:

One is without PFC dedicated circuit, its PFC is generally around 0.65; one is with passive PFC circuit, the lamp board is well prepared, and the PFC is generally around 0.92; the other is active active 7527 / 6561 circuit, PFC can reach 0.99, but the cost of this solution is twice as expensive.

So the second option is more. For passive PFC circuits: also known as valley-filled PFC circuits, the operating voltage range is half the peak value of the AC input voltage. If the input is 180V, its peak value is 180 * 1.414 = 254V, half of the peak voltage is 127V, and minus the step-down voltage drop of 30V, the maximum output is 90V, so the maximum number of LED lamp beads in series is 28 strings.

Therefore, in order to obtain a relatively large power factor, the number of lamp beads connected in series should not be too much, otherwise, the requirements of low voltage cannot be achieved.

7. What is the most suitable constant current accuracy of LED fluorescent lamp power supply?

The constant current accuracy of some power supplies on the market is too poor. Constant current solutions such as the popular PT4107 / HV9910 / BP2808 / SMD802 solutions on the market have an error of ± 8% or ± 10%, and the constant current error is too large. Generally, it is sufficient to be within ± 3%. According to an error of 3%, 6 channels are connected in parallel, and the error of each channel is about ± 0.5%. If 12 channels are connected in parallel, the error of each channel is about ± 0.25%, which is enough accuracy. If the accuracy is too high, the cost will increase significantly. And for LEDs, 17 mA and 17.5 mA have little effect.

8.Isolated / non-isolated

Generally, if the isolated power supply is made into 15W and placed in the LED tube, the transformer is very large and it is difficult to put it in. Especially for the T6 / T8 tube, it is almost impossible, so the isolation can generally only achieve 15W, rarely more than 15W, and the price is very expensive. Therefore, the cost-effectiveness of isolation is not high. Generally, non-isolation has more mainstream, and the volume can be made smaller, and the minimum can be 8 mm high. In fact, non-isolated security measures are in place, and there is no problem.

9. LED fluorescent lamp power efficiency

Output power (voltage of output LED * output current / input power). This parameter is particularly important. If the efficiency is low, it means that a large part of the input power is converted into heat. If it is installed in the lamp, it will generate a high temperature. In addition, our LED has a light efficiency ratio. Dissipating heat will add up to higher temperatures.

The life of all the electronic parts inside our power supply will shorten as the temperature rises. Therefore, efficiency is the most fundamental factor that determines the life of the power supply, and the efficiency cannot be too low, otherwise the heat consumed on the power supply is too large.

Generally more than 80% is sufficient, but the efficiency is related to the matching connection of the lamp board.

10, LED fluorescent lamp power supply size

Height is the main factor of limitation. Generally, the size for T6 tube / T8 requires that the height should not be too high ≤ 9 mm. The height of the T10 tube is ≤15 mm. The length can be longer, making it easier to dissipate heat.

The above are the ten basic characteristics of LED fluorescent tube power supply. When purchasing LED fluorescent tube power supply, you can choose the most suitable driving power supply according to the characteristics mentioned above. As a professional LED lighting manufacturer in Shenzhen, Baite Lighting is a regular power supply produced by the brand manufacturer. Please rest assured to buy.