LED basics: classification and driving of LED products

With the advancement of semiconductor lighting technology and the expansion of applications, there are many classifications of LED products, such as LED according to the color of the light-emitting tube, the light-emitting surface of the light-emitting tube, the structure of the light-emitting tube, the luminous intensity, the working current, the chip material and the function, etc. Unused classification method. In today's article, the first LED network () Xiaobian simply introduces six classification methods for beginners to learn and understand.

(1) Classification according to the color of the luminous tube

According to the color of the luminous tube, it can be divided into red, orange, green (also subdivided into yellow-green, standard green and pure green), blue light and so on. In addition, some LEDs contain chips of two or three colors.

Luminous tubes emit different colors

The light-emitting diodes of the above various colors can be classified into four types of colored transparent, colorless transparent, colored scattering and colorless scattering according to whether the light-emitting diode is doped with or without a scattering agent, colored or colorless. The scattering type LED is suitable for use as an indicator light.

More classification of LED products

(2) Classification according to the characteristics of the light-emitting surface of the luminous tube

According to the characteristics of the light-emitting surface of the light-emitting tube, a round lamp, a square lamp, a rectangular shape, a surface light-emitting tube, a lateral tube, a surface-mounted micro tube, and the like are used. The circular lamps are divided into φ2mm, φ4.4mm, φ5mm, φ8mm, φ10mm, and φ20mm according to the diameter. In foreign countries, a φ3 mm light-emitting diode is generally referred to as T-1; φ5 mm is referred to as T-1 (3/4); and φ4.4 mm is referred to as T-1 (1/4).

The angular distribution of the circular luminous intensity can be estimated from the half value angle size.

There are three types from the angular distribution of luminous intensity:

(1) High directivity. It is usually a pointed epoxy package or a metal reflective cavity package with no scattering agent. The half-value angle is 5°-20° or less, and it has high directivity. It can be used as a local illumination source or combined with a light detector to form an automatic detection system.

(2) Standard type. Usually used as indicator light, its half-value angle is 20°-45°.

(3) Scattering type. This is an indicator light with a large viewing angle, the half value angle is 45°-90° or more, and the amount of the scattering agent is large.

(3) Classification according to the structure of the light-emitting diode

According to the structure of the light-emitting diode, there are structures such as a full epoxy encapsulation, a metal base epoxy package, a ceramic base epoxy package, and a glass package.

(4) Classification according to luminous intensity and working current

LEDs with ordinary brightness according to luminous intensity and operating current (lighting intensity 10mcd); high-intensity light-emitting diodes with luminous intensity between 10 and 100mcd. Generally, the operating current of LEDs is between ten mA and tens of mA, while the operating current of low-current LEDs is below 2 mA (the brightness is the same as that of ordinary LEDs).

(5) Classification according to power

There are low-power LEDs (0.04-0.08W), medium-power LEDs (0.1-0.5W), and high-power LEDs (1-500W). With the continuous development of technology, the power of LEDs is getting bigger and bigger.

(6) Classification according to package form

One is SMD (patch) and DIP (inline).

The author explains: For the classification of LEDs, everyone has a sense, the real distinction is to see the real thing and the actual application to distinguish.

LED drivers are usually divided into three types

If the LED product is like a person, then LED is the soul of the LED product, the drive circuit is the body of the entire LED product, playing a vital role in the quality of the LED product. Since the driver is so important, what is the LED driver? Drives are divided into several types? With these questions, let us learn the following.

Simply put, the LED driver is a circuit that provides normal working conditions (including voltage, current, etc.) for the LED. It is also an indispensable condition for the LED to work. A good driver circuit can also protect the LED at any time. After all, the LED is the whole. The core of the product.

LED drivers are usually divided into three types:

(1) Restriction current drive

formula

Resistance current limiting circuit diagram

Simply connect the resistors in series with the LEDs. By adjusting the resistance of the resistors, the drive current of the LEDs can be changed.

(two) constant current drive

High-power LED constant current drive scheme

Keep the LED current constant, let the LED work under constant current conditions. In order to improve the efficiency and stability of LED illumination and reduce the brightness of LED, constant current drive is the best choice. High power LED Both use constant current drive.

(3) Constant voltage drive

LED constant voltage drive

Keep the voltage across the LED constant, because the voltage of each color LED is not the same, so the LED is rarely driven by constant voltage.