The dynamic response of the LED drive chip is a very important parameter which directly affects the LED display effect, such as brightness consistency, fluency, etc. A good chip should achieve maximum brightness uniformity. The width of OE will affect the chip. Its enable signal can control brightness over the entire screen, as well as display blanking, which can be controlled by adjusting its duty cycle. When the enable signal is abnormal, the whole screen will appear unlit, dark or trailing.
At present, the industry’s requirements for LED displays are getting higher and higher, mainly for the richness of colors, the consistency of brightness, etc., which puts more stringent requirements on chip manufacturers to achieve gray scale. With continuous improvement, the color can be more and more abundant. According to the short board theory of the barrel, the minimum pulse width and reaction time of OE determine the number of gray levels. The reduction in the OE width is an important indicator of the increasing in chip response rate. In order to shorten the OE pulse width of the drive chip, many chip designers are more willing to sacrifice linearity, which is the relationship between input data and output brightness. Generally, the chip ignores the linearity. At the same time, the definition of the shortest OE pulse width is different for each manufacturer. Many chip manufacturers define the time that the output can react as the shortest OE pulse width. The macro performance is that they find the critical point of OE enable (that is, the OE width between normal and screen flash)when the display shows normal, so that linearity will not be taken into consideration, as long as the LED display work well. Then they define the OE width at the moment as the minimum width.
The OE width is the corresponding indicator of the output current from the port: It is generally around 250ns in the industry. The drive chip in this width can generally meet the requirements of static screen and quarter scan screen. However, with the cost control of display manufacturers and the improvement of the manufacturing process of LED light dot, the brightness requirements can be more and more satisfied. The display screen will also develop toward the high scanning mode, tending to one eighth, one-sixteenth scanning mode, or higher. This reduces the number of drive ICs and reduces the area of the PCB. This also puts forward new requirements for the drive IC. It needs to achieve the improvement of the constant current accuracy (and the brightness consistency of the display screen) under the premise of rapid response.
CYT5024 has been specially designed to avoid the problem of OE and brightness linearity. It strives to achieve maximum linearity under the condition of ensuring up to 48 ns OE width. In the application of multi-state scanning, various indicators such as display fluency and the richness of color are excellent.