What Is the Use of the Small Circuit Board Inside the LED Lamps

Nowadays, LED lamps have become the mainstream of lighting, and few families use incandescent lamps. Its main advantage is that led lamps are more energy-saving. Under the same light efficiency, the electric energy consumed by LED lamps is more than 70% less than that of incandescent lamps. The service life of LED lamps is longer than that of incandescent lamps. People who have used incandescent lamps know that the tungsten wire in them will burn out after a short period of use. According to statistics, the average service life of incandescent lamps is about 1000 hours, that is, they can only be used for about 100 days, about 3 months. The service life of LED lamps can reach 100000 hours, that is, the theoretical service life can reach 10 years. Some people will say, how can it be so long? It breaks after a few months of use. This is only a theoretical value. The actual service life is related to the driving circuit design of LED beads. In order to save cost and simplify design, many manufacturers lead to unstable current and voltage of LED lamps, which reduces the service life of LED lamps.

Household lighting LED beads belong to low-voltage and small current devices. Their working voltage is generally about 3V and working current is about 20mA. Lighting LED lamp beads requires LED driving circuit, so a small circuit board in LED lamps is led lamp driving circuit board.

Functions of common LED lamp driving circuit board

1. Simple LED lamp driving circuit board with capacitive resistance step-down, rectification and filtering methods.

The circuit board in this way has the advantages of simple structure and cost saving, but the circuit is unreliable, high failure rate and short service life of LED lamps.

The following figure shows the circuit diagram of LED lamp with capacitance resistance step-down mode. 220V AC capacitance resistance step-down, and then DC voltage is obtained through rectification and filtering to directly drive LED lamp beads.

2. LED constant voltage drive board.

The following figure shows the LED constant voltage driving board. Its circuit principle is equivalent to a switching power supply. The constant voltage output by the switching power supply directly drives the LED bulb.

The principle of switching power supply is shown in the figure below. 220V AC is transformed into about 310V high-voltage DC through rectifier bridge, and then the switching tube is turned on / off at high speed through PWM modulation to form alternating current signal, output AC voltage through high-frequency transformer, and then rectifier and output DC.

3. LED constant current source driving board.

The constant current source driving effect of LED is the best. The brightness of LED lamp is uniform, not easy to be damaged and has a longer service life.

For example, the following figure shows the principle of constant current source driving LED lamp, which is designed by bp3122 constant current source driving chip, in which R1 is the current sampling resistance. Changing the resistance value of R1 can change the load current.

Summary: Lighting LED lamp beads requires LED driving circuits. Generally, LED driving circuits include constant voltage drive, constant current drive, PWM drive, etc., which is the role of LED lamp small circuit board.