Since the LED electronic display has been hailed as the fourth screen of the city, it seems that the cities with developed economies are surrounded by LED electronic displays overnight, so the popularity of LED electronic displays can be popular all over the world overnight! It is said that he has the world's third most advanced light source technology! So in the course of which the LED display LED display ability to drive or what the problem is not solved it?
LED driver chips can be divided into general-purpose chips and dedicated chips. General-purpose chips are generally used for low-end products of LED displays, such as single and dual-color screens in indoors. The most commonly used general-purpose chip is the 74HC595, which has an 8-bit latch, a serial-to-parallel shift register, and a three-state output function. Each channel can output a maximum of 35 mA (not constant current). General IC manufacturers can produce such chips.
Since the LED is a current-characteristic device, that is, under the premise of saturation conduction, its brightness changes with the magnitude of the current, and does not change with the voltage across it. Therefore, one of the biggest features of the dedicated core 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. The following will focus on the dedicated driver chip for LED displays.
Problem
1 power consumption and heating problems
Due to the large output current, the power consumption and heat generation of the LED display chip have always been the first factor hindering the development of the driver chip. This problem will become more prominent in the way that handheld LED displays may appear in the future. As the level of LED device manufacturing processes advances and the drive current decreases, the problem is gradually resolved.
2 Application cost issues
A mainstream 16-bit steady-state current LED display driver chip can only drive 16 LED devices. A LED display with a resolution of 1 024×768 must use multiple driver chips to achieve the desired results, which makes the material cost relatively high. If the driver chip itself is scanned, then a mainstream driver chip can drive multiple LED devices at a time, which will reduce the application cost.
3 Summary
Judging from the product structure of these LED driver chip manufacturers, the current mainstream chips are mainly divided into three grades. The first grade is a chip with a gray scale mechanism. This type of chip has a PWM function inside, which can generate gray scale according to the input data, and is more likely to form deep gray scales and display high quality images. The second grade is a chip with output open-circuit detection (LOD), temperature over-temperature protection (TSD), and brightness adjustment. These chips are more suitable for specific applications due to additional functions, such as for variable information boards. It has the ability to detect LEDs. The third file is a constant current source chip without any additional functions. This type of chip only provides a constant current source for the LED, ensuring good display quality of the screen.
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