12V-LED and distributed constant current technology

introduction

In the past few years, we have advocated "first constant pressure, then constant current", which will be the mainstream of the LED lighting market. After two years of development, it has been rigorously defined as the "distributed constant current" technology. Although major companies, many experts and scholars are committed to the "LED lighting power supply" research, we still see the switching power supply! To this end, it is concluded that constant current power supply will not be the focus of future development. We can't clearly know how customers want to apply LEDs. How many LEDs are needed in series? How many parallel designs are needed? Hundreds of companies have a hundred needs, which cannot be the right direction.

Throughout the development of historical lighting, it is limited to several nominal powers. The larger the market size, the smaller the specifications are needed, which is conducive to maximizing scale, cost and benefit. Today it is assumed that we have designed LED constant current sources with many specifications. It is not necessarily a good thing, and it is not necessarily closer to the market. On the contrary, the more the power supply specification is designed, the more it will deviate from the market. In fact, it does not understand the future development ideas, a route that is not in the right direction.

We believe that the previous companies in the design of LED packaging, mostly consider the LED package itself, combined with less consideration of application design, which will be the form of future lighting package. LED lighting manufacturers are striving to develop power supplies to adapt to LED package forms, too many packaging forms and numerous design concepts, so that our power supply design is impossible. In turn, the LED light source directly adapts to the switching power supply, and everything becomes simple, because the switching power supply has become very standardized and stable after several decades of development and technology precipitation.

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

1. 12V LED importance

We always think that it is: first constant pressure, then constant current. It is recommended that the voltage nominal value package LED, namely: 12V, 24V, 36V, 48V nominal voltage value, because these voltages are the nominal value of the universal power supply. In development, it was found that as long as the focus packaged 12V LED can be applied to all nominal voltages, the latter voltages are multiples of 12V. The single LED package is 12V, the string 2 design is 24V, the 3 is 36V, and the 4 is 48V. Visible the importance of 12V LED.

To make the LED package 12V is not as simple as imagined, the chip is directly connected in series, and the three are less than 10V driving voltage, so the driving power supply is not efficient. A simple 4 series connection exceeds the nominal value of 12V, causing the drive voltage to deviate from the voltage nominal value. There are still some methods, which need to re-cut the LED chip, properly select the appropriate current density, and make the LED package 12V become a reality.

2. Distributed constant current technology

The distributed constant current is: an independent constant current source is established at each parallel branch point, thereby managing, maintaining, controlling the branch and the overall line stability. It can be regarded as a complete line structure in use, and the practical application is constant current control distributed in each node of the line and can communicate with each other. Distributed constant current design LED products have very high product stability. At present, LED products claim to have a large gap with the actual service life. In the case of limited accumulation of drive line design technology, the life of the product is estimated to be far from the actual use. Drive line stability directly affects the overall stability of the product, and distributed constant current has a unique advantage.

Keeping the branch and the overall current stable, it is also convenient to control the management branch and the overall line work, which is the scope of distributed constant current technology. Driving the LED requires a 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, 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 power supply life is a method, there is still a gap between the long-term practical technology accumulation of traditional switching power supplies! In the current street lamp design, the switching constant current module is often used. Compared with the low-dropout constant current IC, the switching constant current efficiency, constant current accuracy, EMI, cost, and reliability are not as good as the low-dropout linear constant current driver. There is absolutely no need for complex constant current modules.

Distributed constant current technology is a series connection, low dropout linear constant current driver on a node that needs constant current. Low dropout is important and is related to product drive efficiency. There are many kinds of constant current driving, in which low-drop differential linear constant current can realize all LED application design, that is, stable and simple, combined with switching power supply, has a perfect constant current driving architecture. Linear constant current drive efficiency is highest in low dropout environments.

The constant current source placement point is flexible. In all parallel branches, no other branch work is affected by the branch current change. Both want to choose LEDs to get load impedance matching, distributed constant current can be designed to be more perfect, the requirements are not very high and can be dispensed with. In order to improve the stability of the lighting products, the current of each branch and the overall line is kept stable.

The constant current source is placed. At each parallel branch node, it can also be an integral constant current point design. The constant current source serial branch can play a good role in a certain position. Generally, the number of constant current drive channels is difficult to match with the design, and the distributed constant current has a high degree of design flexibility.

The biggest feature of distributed constant current technology is that the AC power supply part continues to use the traditional switching power supply, 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 power supply life is a method, there is still a gap between the long-term practical technology accumulation of traditional switching power supplies! In the current street lamp design, the switching constant current module is often used. Compared with the low-dropout constant current IC, the switching constant current efficiency, constant current accuracy, EMI, cost, and reliability are not as good as the low-dropout linear constant current driver. There is absolutely no need for complex constant current modules.

Distributed constant current technology is a series connection, low dropout linear constant current driver on a node that needs constant current. Low dropout is important and is related to product drive efficiency. There are many kinds of constant current driving, in which low-drop differential linear constant current can realize all LED application design, that is, stable and simple, combined with switching power supply, has a perfect constant current driving architecture. Linear constant current drive efficiency is highest in low dropout environments.

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