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What factors LED lamp power supply design should pay attention to?

 At present,The LED fluorescent lamplightingThe market is active,LED drive power supplyMainly divided into three types: the first is to developThe LED chiporLED lightsConveniently downstream factories, permeability;The second type is the original do is general lighting factory;The third class is a completely new factories, they used to do the power supply or other products or new business.

LEDFluorescent lamp power supply

      The LED fluorescent lamp power supply is a very important part in the LED fluorescent lamp, if choose undeserved, LED fluorescent lamp play out his proper performance, and even may not be able to normal lighting use.Here are the LED fluorescent lamp lighting power supply made some small Suggestions, reference for your reference.

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

       LED semiconductor features determine its are greatly influenced by the environment, such as temperature, LED the current will increase;The increase of the voltage, the LED current will increase.More than rated current job for a long time, can greatly shorten the service life of the LED.And the LED constant current is in the environmental factors such as temperature and voltage changes, to ensure the working current constant.

2. How do the LED fluorescent lamp power to matching with light?

        Some customers design lamp panel first, then find the power supply, find it difficult to have a suitable power supply, voltage or current is too big, too small (such as I > 350 ma, V < 40 V);Voltage or current is too small, too high (such as I < 40 ma, V > 180 V), the result is a serious fever, low efficiency, or the input voltage range is not enough.

        In fact, choose one of the most excellent way of string and add on each LED voltage current is the same, the effect of the power supply, can play the best performance.Is the best way to communicate with power supply manufacturer, tailored.

3. How much is the working current of the LED fluorescent lamp power supply is the most appropriate?

        Generally the rated working current of the LED 20 milliampere, some factories use from the start, 20 milliampere design, in fact this electrical work shed fever is very serious, through the contrast test for many times, designed to 17 ~ 19 milliampere is ideal, the recommended design for 18 milliampere.

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

        LED the recommended working voltage is 3.0 3.5 V, after the test, most of the work in 3.125 V, so the calculated at 3.125 V type is quite reasonable.M a lamp bead series, the total voltage = 3.125 * M.

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

        To make the LED fluorescent lamp work in the input voltage range is wide range (full voltage) AC85 ~ 265 v, the LED lamp board series parallel way is very important.Because of the power supply is not commonly isolated buck type power supply, the requirement of wide voltage, output voltage not over 72 v, the input voltage range is 85 ~ 265 v can reach.That is to say, the serial number of not more than 23 string.

        Parallel number not too much, otherwise the working current is too large, fever, recommended for 12 and 6 and 8 and / /.The total current is not more than 240 milliampere as well.Solution, there is a wide voltage is the voltage with L6561/7527 first push up to 400 v, and then step down, the equivalent of two switching power supply, cost is twice as expensive, the performance-to-price ratio is not high, no market.

6. LED series parallel with PFC power factor and wide voltage relationship is what kind of?

        Currently on the market power PFC has three conditions: one is without special PFC circuit, the PFC general at around 0.65;One kind is with passive PFC circuit, light board horse well prepared, PFC general at around 0.92;And with a is made of active active 7527/6561 circuit, PFC can reach 0.99, but the cost of this solution more expensive than the second scheme.

So the second solution is more.For passive PFC circuit, also called valley type PFC circuit, the working voltage range is half the peak of the ac input voltage.If input is 180 v, the peak is 180 * 1.414 = 254 v, half the peak voltage is 127 v, subtracting the step-down type differential pressure 30 v, its maximum output is 90 v, soLED lights,The maximum number of tandem 28 series.

To get bigger of the power factor, therefore, lamp bead series number cannot too much, otherwise, to reach the requirements of low voltage.

7. The LED fluorescent lamp power constant current amount of accuracy to be the most appropriate?

       Some poor precision of constant current power supply in the market as the market popular PT4107 / HV9910 / BP2808 / SMD802 solutions of constant current, error of 8% plus or minus or plus or minus 10%, constant current error is too big.General requirements in the plus or minus 3%.

      According to the error of 3%, 6 road in parallel, each way of error of plus or minus 0.5%, about if parallel is 12 road, every road of error of plus or minus 0.25%, about the precision is enough.Precision is high, the cost will increase greatly.And for the LED, 17 milliampere and 17.5 milliampere.

8. Isolation/not isolation

      General isolation power supply such as make it 15 w, is placed within the LED lamp, its transformer volume is very big, it is difficult to put in.Especially for T6 / T8 tubes, almost impossible, so normally only do 15 w, the isolation of little more than 15 w, and the price is very expensive.So segregation ratio is not high, generally is the isolation of the mainstream is more, the volume can be made smaller and the smallest can do 8 mm high, in fact, the isolation security measures ready, there is no problem.

9. The LED fluorescent lamp power efficiency

      Power output (output leds * output current/voltage input power).If this parameter is especially important, low efficiency means that a good portion of the input power is converted into heat;If it is installed inside the tubes will generate a very high temperature, plus we have LED a photosynthetic efficiency than send out quantity of heat, can produce higher temperature superposition.

And all electronic parts within our power supply will increase with increasing temperature and shorten service life.So efficiency is the most fundamental factor decision power life, efficiency cannot be too low, otherwise consume too much heat on the power supply.In more than 80% commonly, however, the efficiency related to the lamp plate matching connection.

10. The LED fluorescent lamp power size

      Height is the main factor limiting, commonly used in the size of the T6 tube/T8 high height are requested not to 9 mm or less.The height of the T10 tube 15 mm or less.Length can be longer, more easy to heat dissipation.

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