12V packaged LED and distributed constant current technology

By packaging LEDs into 12V, the problems of difficult power supply design , short power supply life, and high price are completely solved . The most stable, most cost-effective and economical product architecture is designed by using "distributed constant current". Combined with 12V packaging, the nominal power supply value will be unified. The power supply design is adapted to the LED specifications, and the LED packaging is adapted to the nominal power supply voltage.

We believe that previous companies mostly considered the LED package itself when designing LED packages, and paid less attention to the application design, which will be the future lighting package form. LED lamp manufacturers strive to develop power supplies to adapt to LED package forms. Too many package forms and numerous design concepts make it difficult for us to design power supplies. On the contrary, LED light sources directly adapt to switching power supplies , and everything becomes simple, because switching power supplies have become very standardized and very stable after decades of development and technological precipitation.

The main research focus of LED lighting products is on the secondary DC part, distributed constant current architecture, and solving the LED packaging technology that adapts to lighting. This is the focus of our discussion today.

1. Importance of 12V LED

We have always believed that: constant voltage first, then constant current. We advocate packaging LEDs with nominal voltage values, i.e., 12V, 24V, 36V, and 48V nominal voltage values, because these voltages are universal power supply nominal values. During development, we found that as long as we focus on packaging 12V LEDs, they can be used in all nominal voltages, because the following voltages are multiples of 12V. A single LED is packaged as 12V, and a string of 2 LEDs is designed to be 24V, 3 LEDs is 36V, and 4 LEDs is 48V. This shows the importance of 12V LEDs.

It is not as simple as imagined to package LEDs at 12V. If the chips are directly connected in series, the driving voltage of 3 chips is less than 10V, which is not efficient. Simply connecting 4 chips in series exceeds the nominal value of 12V, causing the driving voltage to deviate from the nominal voltage value. There is still a way, which requires re -cutting the LED chips and appropriately selecting the appropriate current density to make the LED package 12V a reality.

2. Distributed constant current technology

Distributed constant current means: an independent constant current source is set up at each parallel branch point to manage, maintain and control the stability of the branch and the overall line. In use, it can be regarded as a complete line structure, and the actual application is the constant current control distributed at each node of the line and can communicate with each other. Distributed constant current design LED products have very high product stability. At present, there is a large gap between the claimed and actual service life of LED products. With limited accumulation of drive line design technology, the evaluation of product life is far from actual use. The stability of the drive line directly affects the overall stability of the product, and distributed constant current has unique advantages.

Keeping the branch and the whole current stable and being able to conveniently control and manage the branch and the whole line work are the scope of the distributed constant current technology. Driving LED requires constant current, but the magnitude of the current depends on the application environment. The intelligent development of LED lighting is the key, and the distributed constant current technology fully reserves the intelligent interface .

The biggest feature of distributed constant current technology is that the AC power supply part continues to use the traditional switching power supply and constant voltage power supply mode. The accumulation of switching power supply technology will create quality conditions for LED power supply design. Although accelerating aging to estimate the life of the power supply is a way, there is still some gap with the long-term practical technology accumulation of traditional switching power supplies! In the current street lamp design , switching constant current modules are mostly used. Compared with low-voltage difference constant current ICs , switching constant current efficiency, constant current accuracy, EMI , cost, and reliability are not as good as low-voltage difference linear constant current drive. There is no need for complex constant current modules.

The constant current source can be placed flexibly in all parallel branches, and the change of branch current will not affect the operation of other branches. Everyone hopes to select LEDs to match the load impedance. Distributed constant current can be designed to be more perfect, and the selection can be exempted if the requirements are not very high. Only by keeping the current of each branch and the overall line stable can the stability of the lighting product be improved.

Distributed constant current technology is to connect low voltage difference linear constant current drivers in series at nodes that require constant current. Low voltage difference is very important and is related to product driving efficiency. There are many ways to achieve constant current drive, among which low voltage difference linear constant current can realize all LED application designs, which is stable and simple. Combined with switching power supply, it has a perfect constant current drive architecture. In a low voltage difference environment, linear constant current drive has the highest efficiency.

The constant current source is placed at each parallel branch node, or it can be an overall constant current point design. The constant current source can play a good role at a certain position in the series branch. Generally, the number of constant current drive channels is difficult to match with the design, and distributed constant current will have a high degree of design flexibility.

In the design of LED lighting circuit, AC power supply needs feedback circuit, matching the output LED drive number and driving efficiency rationality. In the distributed constant current drive source, each drive source can directly complete the optocoupler feedback task. The drive circuit has 0 devices around it, which is our goal. The 0 devices around it will not bring about the accumulation of design device parameter errors, and the constant current accuracy caused by the accumulation of peripheral device errors will rise to 0.

3. Conclusion

With the rapid development of LED technology, LED will become one of the main lighting sources, unify the driving design ideas, clarify the design ideas, use more optimized design methods and breakthrough architecture development to make due contributions to the development of LED lighting technology! This article will use this opportunity to explain the application principle, prospects and significance of packaged 12V LED combined with distributed constant current, hoping that this industry will have greater breakthroughs.