Outdoor LED electronic display current drive design principle details

Time:2018-12-04 Views:123

As the largest outdoor application product, LED electronic display is indispensable for large entertainment, sports events, square screens and other places. From simple single-color and two-color text display to today‘s high-definition full-color display, the technology of LED electronic display has been improving, 80% of the global LED electronic display is produced in China.The quality assurance of the display screen is inseparable from the stable current design.

Origin of 16-bit shift constant current IC: two-color screen is mainly to display text, SCM scanning is more convenient, due to the increase in the number of LED, in order to save O/I resources, 74HC595 shift scanning.In order to be more suitable for LED application, the constant current setting function is integrated on this basis, and the current driving capacity is increased. In addition, 16-bit devices are packaged to meet the requirements and cost requirements, which are widely used in full color screens.

The current driving capacity keeps decreasing. Previously, TLC5940 was as high as 120mA for single-channel driving current. Later, the current driving capacity of TB62726, ST2221 and MBI5026 was reduced to 80-90ma.Currently, 45mA current driving capacity is basically used, such as MBI5024 and CYT62726.The current driving ability is reduced mainly because LED devices have higher and higher luminous intensity. In order to improve the image quality, more and more static screen designs are adopted, and the driving current ability is reduced.From the perspective of IC cost, the chip size can be reduced, thus reducing the cost. For this reason, 25mA static screen driver chip CYT62727 is designed.

At present there are 80% of the global sourcing LED screen from mainland China, generally used 16-channel constant current devices design, in the short term will continue to continue, at least the next five years will not disappear, mainly supporting control technology is mature, the product has been serialized, unless the system control technology and chip driver design has a huge leap, further reduce the cost, otherwise the situation will not change.In recent years, many companies have continuously launched new structures, which will be recognized by the market in the future.The biggest problem is through the control technology, if you change the LED color consistency.

There are still many technical deficiencies in China, the government‘s strong support for shenzhen LED display enterprises, so that many indoor LED display manufacturers are actively engaged in the ranks of technology research and development, at present, each LED display manufacturers have applied for their own research and development patents;The application of some LED chips in the market in China indicates that the technology of LED industry in China is progressing and showing a thriving scene.