The analysis of several problems of LED fluorescent lamp power often appear

1, why must be constant:

Properties of LED semiconductor decided its are affected by environment. For example, elevated temperature variation, LED current is increased, the increase of the voltage, LED current will increase. Long term exceeds the rated current, will shorten the service life of the LED. While LED is in constant temperature and voltage variations and other environmental factors, to ensure that the working current of the same.

2, LED fluorescent lamp power supply and light plate:

Some customers to design the lamp panel, then find the power, find it difficult to have adequate power supply, voltage or current is too large, too small (such as I>; 350mA, V<; 40V); or the current is too small, the voltage is too high (such as I<; 40mA, V>; 180V), the result is a serious fever, low efficiency, or the input voltage range is not enough. In fact, choose one of the most excellent string and connection mode, and on each LED voltage and current are the same, but the power's effect is to play the best performance. The best way is to communication and power supply manufacturers, tailored.

3 LED:

Rated current of 20 mA LED, some factories started to use as much as 20 mA, in fact, the current work of heating is very serious, after repeated experiments, designed as 17 Ma is an ideal. The total current =17*N N circuit parallel;

 4, LED:

The recommended operating voltage LED is 3.0-3.5V, after testing, most of the work on the 3.125V, so the 3.125V formula is reasonable. The total voltage =3.125*M M lamp series

5 LED light plate:

The range of AC85-265V to make LED fluorescent lamp in the wider input voltage, the lamp panel series parallel LED mode is very important. Due to the current power supply for non isolated buck power, at the request of wide voltage, the output voltage does not exceed 72V, the input voltage range can reach 85-265V. That is to say, the series number of not more than 23 series. Parallel number is not too much, otherwise the working current is too large, serious fever, recommended for 6 and /8 and /12 and. The total current does not exceed 240 Ma as well. There is a wide voltage scheme, is to use L6561/7527 to voltage up to 400V, and then buck, equal to two of a switching power supply, cost twice as expensive, the price is not high, there is no market.

 6, LED:

At present, the power PFC on the market there are three situations: one is without PFC special circuit, the PFC in general about 0.65; one with passive PFC circuit board, light horse prepared well, PFC in general about 0.92; also used one is the use of an active 7527/6561 circuit to do, PFC can reach 0.99, but the project cost more than twice as expensive as second kinds of scheme. So the second schemes are more. For passive PFC circuit: also called the valley fill circuit of PFC, half of the AC input voltage peak is the operating voltage range. If the input is 180V, the peak value is 180*1.414=254V, half peak voltage is 127V, minus the step-down pressure 30V, the maximum output is 90V, so the LED lamp series number 28 on. Therefore, to get the power factor is relatively large, series number can not be improved too much, otherwise, it is not up to the requirements of low voltage.

7, the precision of constant current:

Market some power supply constant current accuracy is poor, like the popular PT4107/HV9910/BP2808/SMD802 scheme of constant flow scheme, the error is within ± 8% and ± 10%, error constant too large. General requirements can be within ± 3%. According to the 3% errors, 6 parallel, error of each road about ± 0.5%, if 12 parallel, error of each road about ± 0.25%, the accuracy is enough. Precision is high, the cost will increase greatly. But for LED, 17 Ma and 17.5 Ma has little effect.

8, isolation / non isolation:

The general power supply such as a 15W, in the LED tube, the volume is large, it is difficult to put in. Especially for T6/T8 lamp, almost impossible, so in general can only be isolated to 15W, rarely more than 15W, and the price is very expensive. So, isolation of the price is not high, the general non isolated mainstream more, the volume can be made smaller, the minimum can be 8 mm high, in fact, security measures of non isolated well, there is no problem.

9, power supply efficiency:

Output power (voltage output LED current output / input power). This parameter is very important, if the low efficiency means that a large part of the input power is converted into heat emitted; if it is installed in the lamp will be produced in a high temperature, a light efficiency of our LED plus than the heat, will overlay produces higher temperature and power supply. All of our electronic component life will decrease with the temperature rising. So the efficiency is the most fundamental factor power life, efficiency is too low, otherwise the consumption in power on the heat is too large. In general more than 80% can, however, efficiency and light plate matching connection related.

10, size:

Height is the main factor limiting, generally used for T6 tube /T8 size requirements can not be too high than 9 mm in height. T10 LED Tube.