What does PCB mean in lighting?
Nowadays, LED lamps have become the mainstream of lighting, and there are very few households using incandescent lamps. Its main advantage is that LED lamps are more energy-efficient. Under the same luminous efficiency, LED lamps consume more than 70% less electricity than incandescent lamps. The lifespan of LED lamps is longer than that of incandescent lamps. Anyone who has used incandescent lamps knows that the tungsten filaments inside will burn out after a short period of time. According to statistics, the average lifespan of incandescent lamps is about 1,000 hours, that is, on average every day. For 10 hours, it can only be used for about 100 days, which is more than 3 months. The service life of LED lights can reach 100,000 hours, that is, the theoretical service life can reach 10 years. Some people would say, how can it be so long? It will be broken after a few months of use. This is only a theoretical value. The actual life is related to the design of the LED lamp bead drive circuit. Many manufacturers save costs and simplify the design, which leads to the instability of the current and voltage of the LED lamp, which reduces the life of the LED lamp.
Household lighting LED lamp beads are low-voltage and small-current devices, their working voltage is generally about 3V, and the working current is about 20mA. The LED lamp bead needs an LED driver circuit to light up the LED lamp beads, so a small circuit board in the LED lamp is the LED lamp driver circuit board.
Common LED lamp drive circuit board functions
1. Simple LED lamp driving circuit board with capacitive resistance step-down, rectification and filtering methods.
The circuit board in this way has a simple structure and saves costs, but the circuit is unreliable, the failure rate is high, and the life of the LED lamp is short.
The figure below is the circuit diagram of the capacitive resistance step-down method of the 1 layer LED Based Night Lamp. The 220V AC capacitor is used to step down the voltage, and then the DC voltage is obtained through rectification and filtering to directly drive the LED lamp beads.
2. LED constant voltage driver board.
The following picture shows the LED constant voltage driver board of 8 Layer Button Motor Controller Circuits. Its circuit principle is equivalent to a switching power supply, which directly drives the LED lamp beads through the constant voltage output by the switching power supply.
The principle of the switching power supply is shown in the figure below. The 220V alternating current of 12 Layer Touch Activated Switch Circuits is converted into about 310V high-voltage direct current through the rectifier bridge, and then the switch tube is turned on/off at a high speed through PWM modulation, forming an alternating current signal that passes through a high voltage. The frequency transformer outputs AC voltage, and then rectifies and outputs DC power.
3. LED constant current source driver board.
The effect of driving the LED with a constant current source is the best. The brightness of the LED lamp is uniform and not easy to damage, and the service life is longer.
For example, the figure below shows the principle of the industrial control PCB constant current source driving LED lights. The BP3122 constant current source driver chip is used for design, where R1 is a current sampling resistor. Changing the resistance of R1 can change the load current.
Summary: LED lamp beads need LED drive circuit, general LED drive circuit has constant voltage drive, constant current drive, PWM drive, etc. This is the function of the small LED light circuit board.
