Discussion on ten key factors of LED fluorescent lamp power supply design

Currently, LED fluorescent lighting market is more active, LED power supply manufacturers are mainly divided into 3 types:

The first category is the development of LED chips or LED lights to do the factory, homeopathy to downstream penetration, LED power supply circuit knowledge and LED fluorescent lamp power supply knowledge is not much;

The second category is to do the original general lighting factory, we have entered a new product areas, LED power supply circuit knowledge to understand a little, but not much;

The third category is completely new factory, they used to do power or other products or new business, some understanding of LED power, and some are not very understanding.

LED fluorescent lamp power supply is a very important part of the LED fluorescent lamp, if not properly selected, LED fluorescent lamp can not play its due performance, and even may not be able to use the normal lighting. Below I LED fluorescent lighting to do some small suggestions for your reference.

1, LED fluorescent lamp power supply must be constant?

The characteristic of LED semiconductor decides its be affected greatly by the environment, for instance the temperature rises, the current of LED will increase; the voltage increases, the current of LED also can increase. Longer than the rated current, will greatly shorten the service life of LED. The LED constant current is in the temperature and voltage and other environmental factors, to ensure that the working current unchanged.

2, LED fluorescent lamp power can be matched with the lamp board?

Some customers to design the lamp board, then find the power, find it difficult to have the right or power, the current is too large, the voltage is 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 serious fever, the efficiency is low, and the input voltage range is not. In fact, the choice of one of the best series parallel connection, the voltage and current on each LED is the same, and the effect of the power supply can play the best performance. The best way is to communicate with the power supplier, tailored.

3, LED fluorescent lamp power supply current is the most appropriate?

General LED rated current is 20 mA, some factories began to use as much as 20 mA, design, in this current work under heating is very serious, after repeated tests, the design of 17 ~ 19 Ma is ideal, the recommended design is 18 ma.

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 the 3.125V, so the 3.125V formula is more reasonable. The total voltage =3.125*M M lamp series

5, LED lamp board series parallel and wide voltage to how wide?

In order to make the LED fluorescent lamp work in a wide range of input voltage range (full voltage) AC85 ~ 265V, then the LED series is very important. Due to the current power supply is generally non isolated buck power supply, when the demand for a wide voltage, the output voltage does not exceed 72V, the input voltage range is up to 85 ~ 265V. In other words, no more than 23 string series. The number of parallel do not too much, otherwise the working current is too large, severe fever, recommended for 6 and /8 and /12 and. The total current is not more than 240 ma. There is also a wide voltage program, is the first to use L6561/7527 to raise the voltage to 400V, and then buck, equivalent to two switching power supply, the cost of double the cost of this program is not high, there is no market.

6, LED series parallel and PFC power factor and the relationship between the wide voltage is what kind of?

The current PFC power supply on the market there are three types: one is PFC without a dedicated circuit, the PFC is generally around 0.65; one with passive PFC circuit board, the light horse prepared well, PFC is generally around 0.92; also used one is the use of an active 7527/6561 circuit. PFC can reach 0.99, but this program costs more than twice as expensive as second schemes. So more than second programs. For a passive PFC circuit, also known as a valley filled PFC circuit, the operating voltage range is half the peak of the AC input voltage. 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 LED lamp series number 28 series. Therefore, in order to get the power factor is relatively large, the series number can not be too much light, otherwise, it is not up to the requirements of low voltage.

7, LED fluorescent lamp power supply constant current accuracy is the most appropriate?

On the market, some power supply constant current accuracy is too poor, like the popular PT4107/HV9910/BP2808/SMD802 programs on the market, such as the constant flow of the program, the error of 8% + or + + +, the constant current error is too large. General requirements in + 3% on it. According to the error of 3%, parallel to the road, the error of each road is about + 0.5%, if it is in parallel with the road, the error of each road is about + 0.25%, the accuracy of the is enough. Accuracy is too high, the cost will be greatly increased. And for LED, 17 Ma and 17.5 Ma little effect.

8, isolation / non isolation

General isolation power such as made of 15W, placed in the LED lamp, the transformer volume is very large, it is difficult to put into. In particular, the T6/T8 lamp, almost impossible, so the general isolation can only do 15W, more than 15W, and the price is very expensive. So, isolation of the price is not high, generally non mainstream more isolated, the volume can be made smaller, the minimum can be 8 mm high, in fact, the security measures of non isolated well, there is no problem.

9, LED fluorescent lamp power efficiency

Output power (output)