Abstract: The role of the driver IC in the full-color LED display is to receive the internal production time PWM protocol to display the data (receive the video card or processor information from the source). The current output brightness level refresh and other related PMW currents can light up the LED. The display driver IC, logic IC and display peripheral supporting IC work together on the LED display and determine its current display state.
(The article is reproduced from: Sumacro)
Many ICs can be seen on the PCB board on the back of the LED display. What impact and effect will these LED display driver ICs have? This article will introduce you to the role played by ED display driver ICs as well as energy saving and integration trends.
The role of the driver IC in the full-color LED display is to receive the internal production time PWM protocol to display the data (receive the video card or processor information from the source).
The current output brightness level refresh and other related PMW currents can light up the LED. The display driver IC, logic IC and display peripheral supporting IC work together on the LED display and determine its current display state.
LED driver chip category: general and special
The general-purpose chip itself is not specifically designed for LED, but some logic chips have the logic function of the LED display part.
The dedicated chip is a chip specially designed for LED display driving according to the LED light emitting characteristics. LED devices with current characteristics, that is to say, under the premise of saturation conduction, the brightness will change with the change of current, not by adjusting the voltage across it. Therefore, one of the characteristics of the dedicated chip is to provide a constant current. Constant current can ensure the stability of LED drive, eliminating the flicker of LED, is the premise of high-quality LED display. Some special chips for different industries also add some special functions, such as current correction function with LED error detection and current gain control.
Driver IC development
In the 1990s, LED displays were applied on the basis of monochrome, using constant voltage driver ICs. In 1997, China experienced the first-generation LED display dedicated driver IC9701, with a gray scale ranging from 16 to 8192, achieving the WYSIWYG effect. Subsequently, the light-emitting characteristics of LED constant current drive became the choice of full-color LED display drive, and the 16-channel 8-channel drive with higher integration replaced the drive. In the late 1990s, companies such as Toshiba of Japan, TI of the United States, and Riyuecheng of China successively launched 16-channel constant-current LED driver chips. By the beginning of the 21st century, Taiwanese companies also began production and use of driver chips. Now, in order to solve the PCB wiring problem of small-pitch LED display, Riyuecheng has launched a highly integrated 32-scan 48-channel constant current LED driver chip.
Driver IC performance
Among the LED display performance indicators, the image refresh rate and gray scale expression are one of the most important indicators. This requires high consistency of the current between the channels of the LED display driver IC, a high-speed communication interface rate, and a constant response speed. In the past, the relationship between refresh rate, gray scale, and utilization rate has changed. By sacrificing one of these items, one or two of the indicators can perform better. Therefore, in practice, many LED display screens are difficult to achieve both. Either the refresh is not enough, high-speed camera equipment is prone to black lines, or the grayscale is not enough, and the colors are not consistent. With the development of technology driving the development of IC research and development, these problems can now be solved. In the application of LED full-color display, in order to ensure the user's eye comfort for a long time, low brightness and high ash content have become a particularly important standard for testing the performance of driver ICs.
Driver IC trends
1. Energy saving
Green energy saving is the eternal pursuit of LED display screens, and it is also considered to be an important criterion for driving IC performance discrimination. Drive IC energy saving includes two aspects, one is to reduce the constant voltage of the inflection point; the second is to reduce the operating voltage and operating current through optimization algorithms and IC design. The first Idle Stop (dynamic low power consumption) energy-saving technology created by Riyuecheng makes power consumption lower, screen temperature lower, and black screen standby more power-saving, especially suitable for 7 * 24 hours of uninterrupted work of LED display screens.
2. High integration
With the rapid decrease in pixel pitch of LED display screens, the installed packaged devices have grown exponentially, greatly increasing the component density of the modules. For example, in a small-pitch P1.9 LED, 15 scans 160 * 180, 90 modules require 45 rows of constant current driver ICs, 2138. So many available devices make the PCB wiring space extremely crowded, which increases the difficulty of circuit design. At the same time, such cumbersome component layout can easily lead to poor soldering and other problems, and will reduce the reliability of the module. The smaller the number of driver ICs, the larger the PCB layout area. Therefore, the application requirements for driver ICs must be pushed onto the highly integrated technology roadmap. In recent years, Riyuecheng has been devoting itself to the research and development of highly integrated ICs, which has reduced the overall IC usage by 71% compared with traditional ones. It has also reduced the area of the IC itself, reduced the PCB footprint, and brought less Effect.