LED Display Driver IC

LED display driver IC is such a key component, it is like the central nervous system of the human brain, and it is in charge of the body's physical actions and the mental thinking of the brain. The performance of the driver IC determines the effect of the led display screen, especially the use of modern large-scale activities and high-end venues, making people more stringent requirements for LED display driver IC.

The role of the driver IC: Receiving display data (from the receiving card or video processor and other information sources) in accordance with the protocol, producing PWM and current time changes, output PWM current which has relation with LED display brightness, grayscale, refresh rate, etc parameters. to light LED displays. Driver ICs, logic ICs, and peripheral ICs composed of MOS switches work together to display the functions of the LED display and determine the display effect it presents.

The classification of the driver IC: led display driver chip can be divided into two kinds of general-purpose chips and special chips.

The so-called general-purpose chip, the chip itself is not designed specifically for the LED, but some logic chips with a led display part of the logic function.

The special chip refers to the driver chip designed specifically for the LED display according to the LED light emitting characteristics. LED is a current characteristic device, that is, under the premise of saturation conduction, its brightness changes with the change of the current, rather than by adjusting the voltage across it. Therefore, one of the biggest characteristics of a special chip is to provide a constant current source. The constant current source can ensure the stable driving of the LED and eliminate the flickering phenomenon of the LED, which is a prerequisite for the LED display to display a high-quality picture. Some special chips also add special features for different industry requirements such as LED error detection, current gain control, and current correction.

Because led is a current characteristics device, that is, under the premise of saturation conduction, its brightness changes with the change of the current size, not with the change of the voltage across it. Therefore, one of the biggest features of a dedicated chip is to provide a constant current source. The constant current source ensures stable LED driving and eliminates LED flicker.

The problems with LED display driver chips:

1: Application cost

A mainstream 16-bit steady state current LED display driver chip can only drive 16 LED devices. A LED display with a resolution of 1024 x 768 must use multiple drive chips to achieve the desired effect, which results in higher material costs. If the driving chip itself adopts a scanning method, then a mainstream driving chip can drive multiple LED devices at a time, which will reduce the application cost.

2: power consumption and heart problems

Due to the large output current, the power consumption and heat generation of LED display chips have always been the first factor that hinders the development of the driver IC. This problem will become more prominent in the future of handheld LED display drive methods that may occur. With the advancement of the price of LED electronic display screen manufacturing process and the reduction of driving current, problems will be solved gradually.

3: Currently, mainstream chips are mainly divided into 3 levels. The first level is a chip with a gray-scale mechanism. This type of chip has a PWM function inside it. It can generate gray levels based on input data, and it is easier to form deep gray levels and display high-quality images. The second layer is a chip with output open-circuit detection (LOD), temperature over-temperature protection (TSD), and brightness adjustment functions. These chips are more suitable for specific occasions due to additional functions. For example, they are required for variable information boards. With LED detection error. The third level is a constant current source chip without any additional functions. This type of chip only provides a constant current source for the LED and ensures good screen display quality.

Among the LED display performance indexes, image refresh rate and gray scale indexes are some of the most important indexes. This requires high consistency in the flow between channels of the LED display driver IC, high-speed communication interface rate and constant response speed. In the past, the relationship between refresh rate, grayscale, and utilization has changed. By sacrificing one of them to ensure that one or two indicators can perform better. Therefore, it is difficult for many LED display screens to achieve both in practice. Either the refresh is not enough, which tells the camera that black lines are prone to appear in the camera shooting, or the grayscale is not enough and the color is inconsistent. With the development of technology driving the development of IC R&D level, these problems can now be solved. In the application of LED full-color display, in order to ensure long-term eye comfort for users, low brightness and high gray have become a particularly important standard for testing the performance of driver ICs.

The trend of driver IC:

1.Energy saving:

As a green energy source, energy saving is the eternal pursuit of LED displays and an important criterion for considering the performance of driver ICs. The energy saving of the driver IC mainly includes two aspects. One is to effectively reduce the constant current inflection point voltage, thereby reducing the traditional 5V power supply to below 3.8V operation; the second is to reduce the operating voltage and operating current of the driver IC by optimizing the IC algorithm and design. At present, some manufacturers have launched constant current driver ICs with a low 0.2V turning voltage and a 15% improvement in LED utilization. The use of a power supply voltage 16% lower than conventional products reduces heat generation and greatly improves the energy efficiency of LED displays.

2. Integration:

With the downward trend of the pixel pitch of the LED transparent screen, the packaged devices to be mounted on a unit area have increased by a geometric multiple, which greatly increases the component density of the module drive surface and increases the difficulty of circuit design. At the same time, such a crowded arrangement of components can easily cause problems such as poor soldering, and also reduce the reliability of the module. With fewer driver ICs and larger PCB wiring area, the demand from the application side forces the driver IC to embark on a highly integrated technical route.