The concept of common anode and common cathode:
Connect the anode (positive electrode) of each bead of the unit module to supply current uniformly from RGB, and supply current from PCB to bead.
The anode (positive terminal) of the bead of each line of the unit module is connected, and R, G and B are powered respectively. The voltage and current are correctly distributed to the red, green and blue beads, and the current reaches the negative IC terminal through the lamp bead.
The power supply direction is different:
The current of common anode LED display screen flows from the PCB board to the lamp bead, and the RGB lamp bead is powered uniformly, which increases the positive voltage drop of the circuit;
The common cathode LED display current first goes through the lamp bead and then to the IC negative pole, the positive voltage is reduced, the conduction internal resistance is small.
The supply voltage is different:
The common anode LED display usually provides unified power supply to red, green and blue lamp beads with a voltage higher than 3.8V, and the power loss is large;
The common cathode LED display is divided into precise power supply according to the actual voltage required by the red, green and blue chips, with less power loss and correspondingly lower heat generated during the work of LED display.
The effect of energy saving and cooling is different:
Based on precise control voltage, common cathode technology can reduce the power consumption of the system by reducing the supply voltage of the red LED, which can be directly connected without adding line scanning devices to realize the separate power supply of the LED, without excess heat and energy consumption, synchronously reduce the temperature of the screen body, effectively reduce the damage probability of the LED, and theoretically better deal with problems such as poor picture quality and energy saving. The image is more delicate and rich in color, thus improving the stability, reliability and visual experience of the entire display system.
If a total power supply of 5V is used by common anode, and a total power supply of 2.8V is used by common cathode for red LED, other conditions remain unchanged, and the red LED current accounts for 40% of the total current, then the savings of 40%*(5-2.8)/5=17.6%. If the red LED current accounts for 50% of the total current, the savings is 50%*(5-2.8)/5=22%. That is to say, the energy saving level of common cathode is about 17.6%~22%.