Principle of LED control system

The LED control system (LED controller) is to control the switches of various positions in the LED lamp circuit through chip processing. 1. High-power LED control system for low-voltage products Low-voltage LED products generally have a design voltage of 12V-36V, and the number of LEDs in each circuit is 3-6 in series. Resistors are used to reduce voltage and limit current, and the current of each circuit is below 20mA. An LED product is composed of multiple circuits of LEDs. The advantages are low voltage, simple structure, and easy design; the disadvantage is that when the product scale is large, the current is large, and a low-voltage switching power supply is required. Due to the shortcomings of the product, it is impossible to transmit power over a long distance with low voltage, and it is limited to small products, such as signboards, small patterns, etc. According to this feature, the controller design specifications: 12V is controlled by 75A/30V MOS power tube, the output current is 8A/channel; 24-36V is controlled by 60A/50V MOS power tube, the output current is 5A/channel. The user can select the number of controllers according to the above specifications, and can choose NE20 low-voltage series controllers for jumping changes, and NE10 low-voltage series controllers for gradual changes. Note that the LED must be connected to the common anode (+) pole, the controller controls the cathode (-) pole, and the controller does not include a low-voltage power supply. 2. LED control system for high-voltage products. The design voltage of high-voltage LED products is AC/DC 220V. The number of LEDs in each loop is 36-48 in series, and the current of each loop is below 20mA. There are two current limiting methods, one is resistance Current limiting, this method consumes a lot of resistance power consumption, it is recommended to use a 1/4W metal mold resistor connected in series for every 4 LEDs to distribute heat evenly, this connection method is the most stable and reliable at present; the other is to connect resistors and capacitors in series Current limiting, most of the voltage drops on the capacitor in this connection method, and the resistance power consumption is small, so it can only be used in a stable constant light state. If the capacitor is flashed to store energy, the voltage will double instead, and the LED will be easily damaged. All LEDs that use the LED control card must use the resistance current limiting method. Generally, each LED circuit is one meter, the power is 5W, and the three-color power is 15W per meter. Commonly used gradient controllers NE112K control DC 1200W, NE103D AC load 4500W DC load 1500W, if there are many flashing units of the lamp, use NE112K, if you only need overall flashing, use NE103D. If you use the gradient method, pay attention to load matching. The luminous distribution characteristics of neon lights and LED screens are different, and different types of loads cannot be mixed in the same circuit. 3. Serial LED control system for low-voltage LED products The serial control system for low-voltage LED products is characterized by a large number of control channels, and the purpose of control is achieved by using serial signal transmission. Generally, the control of 512 units only needs 4 control lines. The row LED control card needs to be equipped with registers on the LED light source board, and the controller can choose the model NE040S controller. The maximum capacity of the control card reaches 4096KBit. If the LED screen with 512 units of load can achieve a maximum of 8192 frame images. .