Introduction to the working principle of AC LED light source

The working principle of the AC LED light source divides a stack of LED micro-die into five series using an interlaced matrix arrangement process. The AC LED die is composed of a rectifier bridge. The two ends of the rectifier bridge are respectively connected to the AC source, and the other ends are connected. A string of LED dies is connected, the positive half of the alternating current flows along the blue path, the three strings of LED illuminate, the negative half cycle flows along the green path, and three strings of LED dies are illuminated, and the LED dies on the four bridge arms are rotated. The light is emitted, and the LED crystal grains on the bridge arm emit light at the same time, and the middle LED strings are always illuminated due to sharing.

In 60 Hz AC, it will be lit at a frequency of 60 times per second. The DC obtained by the rectifier bridge is pulsating DC, and the LED's illumination is also flashing. The LED has the characteristics of power-off afterglow, and the afterglow can be kept for tens of microseconds. Because the human eye is inert to the flow point memory, the result is The eye's interpretation of the working mode of the LED + light source + afterglow is continuous illumination. LEDs work half the time, half of the time is resting, so heat is reduced by 40% to 20%. Therefore, the life of the AC LED is longer than that of the DC LED.

Mature products of AC LEDs such as AX3201 and AX3211 for AC110V and AX3221 and AX3231 for 220V. For AC110V power is 3.3W ~ 4W, working current is 40mA; AC220V power is 3.3W-4W, working current is 20mA. The LED die is bonded directly to the copper-aluminum substrate.

The typical application of AC LED is very simple. The positive temperature coefficient thermistor PTC and the current limiting resistors R1, R2 and R3 are connected to the two ends of the AC LED. The 110V or 220V AC can be connected to the lighting work.

When the LED is mass-produced, its impedance has a certain dispersion, and AC LED is also the same. In order to facilitate the high-volume application of downstream manufacturers, the LED light source manufacturer will perform the impedance division on the mass-produced products at the factory, when the customer is in use. The current limiting resistor of the corresponding resistance value can be checked according to the VF binning table provided by the LED light source manufacturer.

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