LED display driver and system architecture

LED display as a high-tech product has attracted great attention, the use of computer control, light, electricity into one intelligent full-color display has been applied in a wide range of fields. Its pixels use LED light-emitting diodes, and many light-emitting diodes are arranged in a dot-matrix manner to form an LED array, which in turn constitutes an LED screen. Through different LED driving methods, different effects of the image can be obtained. Therefore, the advantages and disadvantages of the LED driver chip, LED display quality plays an important role. LED driver chip can be divided into general-purpose chip and special chip.

General-purpose chips are generally used for low-end LED display products, such as indoor single and dual-color screen. The most commonly used general-purpose chip is 74HC595, with 8-bit latch, a series of parallel shift register and tri-state output function. The maximum output current per circuit is 35mA non-constant current.

As the LED is a current characteristic device, that is, under the premise of saturated conduction, its brightness changes with the size of the current, not with the change in voltage on both sides of the change. The most important feature of the special chip is to provide a constant current source output to ensure stable driving of LEDs and eliminate the flickering phenomenon of LEDs. With the characteristics of high output current and constant current, it is suitable for occasions requiring high current and high picture quality, such as outdoor full-color screen and indoor full-color screen.

LED display LED driver chip series products SMT5026. SMT5026 built-in CMOS shift register and latch function, you can convert the serial input data into parallel output data format.

Part II: LED display system architecture

(1) Display unit
This is the main part of the LED display screen, composed of light-emitting materials and drive circuitry. Indoor screen is a variety of specifications of the unit display board, outdoor screen is the unit box.

(2)Main controller
The role of the input RGB digital video signal buffer, grayscale conversion, re-organization, and produce a variety of control signals.

(3) switching power supply
The purpose is to change 220V AC power into various DC power to provide to various circuits.

(4)Transmission cable
The display information and various control signals generated by the main controller are transmitted to the screen body by twisted pair cables.

(5)Scanning Controller
The function of this circuit board is to buffer the information and generate various scanning signals as well as duty cycle grayscale control signals.

(6) special display card and multimedia card (video card)
LED full-color screen dedicated display card in addition to the basic functions of the computer display card, but also at the same time output digital RGB signals and line, field, fading and other signals to the main controller. Multimedia card in addition to the above functions can also be input analog Video signal into a digital RGB signal (i.e., video capture).

(7) other signal sources and their external devices
Including computers, televisions, Blu-ray, DVD, VCD, video cameras, etc..