LED has a strong application flexibility, do not understand the drive power of course, will be different. If handled properly, will seriously affect the LED life and lighting conditions, the following to introduce LED drive power in the different applications of the difference, look to know!
1. Introduction to distributed constant current drive principle
In the past, incandescent and energy-saving lamps market, large companies formed by the limited specifications of the mainstream lamps, LED is difficult to continue to comply with. LED has its application flexibility, in the future design will bring more power specifications.
The principle of distributed constant current is that an independent constant current source is established in each parallel branch point to manage, maintain and control the stability of slip and slip, slip road and integral line. Distributed constant current circuit in the use can be regarded as a complete line structure, and the actual application is distributed in the line of each node, is a constant current control and can communicate with each other circuit structure.
At present, LED products claim to have a greater gap with the actual service life. While the stability of the drive line will directly affect the overall stability of the product.
Distributed high-current technology has a high reliability because the AC power supply part continues to follow the traditional switching power supply, using constant voltage power supply mode. Switching power supply technology will give LED power supply design to create quality conditions. In the same power supply specifications, no longer need to develop new power models, power can be backward compatible, greatly reducing the power specifications, improve power uniformity.
2. Soft and hard combination of precision control ideas
In the daily drive power supply design, the surrounding device cumulative error is very difficult to deal with, resulting in drive power parameters from the design of the original difference is far. Constant current drive requires current detection, the usual practice is in the slip in series millipolar resistance to obtain feedback information, to achieve high efficiency, the smaller the resistance value, too small resistance to the production, test inconvenience , The general instrument can not verify the correct value, the production process will also affect the accuracy, the resistance method to set the current is fixed, the adjustment is not convenient.
Soft and hardware combination will open the LED application technology leap. LED constant current accuracy of the value of software, can greatly enhance the flexibility of LED applications. Through the computer operating software, with intuitive digital write to complete the circuit current setting.
Drive the line around the zero device, which is our goal. Peripheral zero devices will not bring the design parameters of the cumulative error, which greatly improve the accuracy of constant current.
China's IC manufacturing process can not meet the current LED drive accuracy requirements, but we can use new technology, new methods to achieve the world's top constant current accuracy level. Driving precision control is one of the methods.
In the precise control of the drive, first of all depends on what the design purpose is in accordance with the highest luminous efficiency, or in accordance with the consistency of the design of the lamp if the drive current is limited, in fact, is very easy to do. Such as the drive current is stable and accurate, or with the temperature changes are protected. Customer requirements of the parameters can meet the requirements, such as product consistency, efficiency and so on.
For these requirements of the customer, we need to work hard on the design drive. In the final analysis, or how to control the accuracy, and ultimately in accordance with our design intent to adjust the current, improve product stability.
Value to achieve. You can choose to have built-in nonvolatile E2PROM. Believe that any register can complete its task, according to the application needs and process conditions permit, determine the type of memory selection.
The division and design of the current order may vary from market to market. Due to manufacturing process causes the output current is always error, after the software will be improved.
Long drive the driver IC at the factory, according to the different needs of customers, to provide different current output value, eliminating the bulk calibration process. Small amount of customers can also use the computer software to rewrite the current value.
3. To improve the efficiency of the design of the new method
AC power-driven LED in a single series of branches is feasible, but the single-series LED driver is only a small part of the application, most of the applications in parallel. In the case of parallel LED drive, the overall constant current design of the branch LED does not necessarily work in the constant current state, the entire product LED current is mutual influence.
In high current designers, such as LED street lamp design, the designer will not direct the multi-channel LED in parallel, because this danger will occur immediately. The usual practice is to first constant voltage and then DC constant current, through these two levels of design completed. We know that the DC drive efficiency is in a reasonable voltage and load conditions, then how to ensure that the number of load LED or LED with temperature changes are within a reasonable range? How flexible to allow customers to change the number of LED drivers? To solve the above problems need to design AC DC constant current feedback mechanism, but so far do not have the technical conditions.
With another approach: only with a distributed constant current driver, can provide optocoupler drive capability, one branch can be used as a representative of all branches. Distributed constant current branch can communicate with each other to achieve adaptive linkage mechanism, while compatible with control, data read and write interface functions. In addition, the surrounding design of the device, the power output voltage and load impedance matching, in order to achieve constant current source and light source integration.