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, when the temperature increases, the current of the LED will increase; when the voltage increases, the current of the LED will also increase. Exceeding the rated current for a long time will greatly shorten the service life of the LED. The LED constant current is to ensure that its operating current remains unchanged when environmental factors such as temperature and voltage change.
2. How can the LED fluorescent lamp power supply match the lamp board?
Some customers design the light board first, and then find the power supply, and find that it is 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); or the current is too small and the voltage is too high (such as I< 40mA, V>180V), the result is serious heat generation, low efficiency, or insufficient input voltage range. In fact, if you choose an optimal series-parallel connection method, the voltage and current applied to each LED are the same, and the effect of the power supply can exert the best performance. The best way is to communicate with the power supply manufacturer first and customize it.
3. What is the most suitable working current of the LED fluorescent lamp power supply?
Generally, the rated working current of LED is 20 mA. Some factories use it up at the beginning. The design is 20 mA. In fact, the working heat is very serious under this current. After many comparison tests, the design is 17-19 mA. Ideally, the recommended design is 18 mA.
4. What is the working voltage of the LED fluorescent lamp power supply?
Generally, the recommended working voltage of LED is 3.0-3.5V. After testing, most of them work at 3.125V, so the calculation formula of 3.125V is more reasonable. The total voltage of M lamp beads in series = 3.125*M
5. How wide should the series-parallel and wide voltage of the LED light panel be?
To make the LED fluorescent lamp work in a wide range of input voltage range (full voltage) AC85 ~ 265V, the LED series and parallel mode of the lamp board is very important. Since 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 to say, the number of concatenations does not exceed 23 strings. The number of parallel connections should not be too many, otherwise the working current will be too large and the heat will be serious. It is recommended to be 6 parallels/8 parallels/12 parallels. The total current does not exceed 240 mA as well. There is also a wide voltage solution, which is to use L6561/7527 to raise the voltage to 400V first, and then step down, which is equivalent to two switching power supplies, and the cost is twice as expensive. This solution is not cost-effective and has no market.
6. What is the relationship between the series and parallel connection of LEDs, PFC power factor and wide voltage?
At present, there are three types of power supply PFC on the market: one is without PFC dedicated circuit, and its PFC is generally around 0.65; the other is with passive PFC circuit, the lamp board is well prepared, and the PFC is generally around 0.92; One is made with active-active 7527/6561 circuit, PFC can reach 0.99, but the cost of this scheme is twice as expensive as the second scheme. So the second option is more. For passive PFC circuit: also known as valley-filling PFC circuit, its operating voltage range is half of 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 buck 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 in series should not be too many, otherwise, the requirements of low voltage will not be met.
7. What is the most suitable constant current precision of LED fluorescent lamp power supply?
The constant current accuracy of some power supplies on the market is too poor. For constant current solutions such as the popular PT4107/HV9910/BP2808/SMD802 solutions, the error reaches ±8% or ±10%, and the constant current error is too large. The general requirement is ±3%. According to the error of 3%, 6 channels in parallel, the error of each channel is about ±0.5%, if it is 12 channels in parallel, the error of each channel is about ±0.25%, the accuracy is enough. If the accuracy is too high, the cost will increase greatly. And for LEDs, 17 mA and 17.5 mA have little effect.
8. Isolation/non-isolation
Generally, if the isolated power supply is made of 15W and placed in the LED lamp, the transformer is very large and difficult to put in. Especially for T6/T8 lamps, it is almost impossible, so the isolation can generally only achieve 15W, and there are very few more than 15W, and the price is very expensive. Therefore, the cost-effectiveness of isolation is not high. Generally, non-isolation is more mainstream, and the volume can be made smaller, and the minimum height can be 8 mm. In fact, there is no problem with non-isolation safety measures.
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 and dissipated; if it is installed in the lamp tube, it will generate a very high temperature, plus a light efficiency ratio of our LED. Heat is dissipated, which superimposes a higher temperature. And all the electronic parts inside our power supplies have their lifespans shortened as the temperature rises. Therefore, efficiency is the most fundamental factor in determining the life of the power supply. The efficiency cannot be too low, otherwise the heat consumed by the power supply will be too large. Generally, more than 80% is enough. However, the efficiency is related to the matching connection method of the lamp board.
10. LED fluorescent lamp power supply size
Height is the main factor of limitation. Generally, the size of T6 tube/T8 requires that the height should not be too high or less than 9 mm. The height of T10 tube is ≤15mm. The length can be longer, which is easier to dissipate heat.
Benwei Lighting is an LED Tube, LED flood light, LED Panel Light, LED High Bay, LED manufacturer with 12 years of experience. If you want to purchase a high-quality LED flood light or have a more in-depth understanding of the application of LED flood lights, please contact send us inquiry， our web: https://www.benweilight.com/.
