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# 14 important parameters of LED chips part one

Feb 20, 2023

1. Forward working current If:

It refers to the forward current value of the light-emitting diode when it normally emits light. In actual use, you should choose IF below 0.6·IFm according to your needs.

2. Forward working voltage VF:

The operating voltage given in the parameter table is obtained under a given forward current. It is generally measured when IF=20mA. The forward working voltage VF of the light-emitting diode is 1.43V. When the outside temperature rises, VF will drop.

3. V-I characteristics:

The relationship between the voltage and current of the light-emitting diode. When the forward voltage is less than a certain value (called the threshold), the current is extremely small and no light is emitted. When the voltage exceeds a certain value, the forward current increases rapidly with the voltage, and light is emitted.

4. Luminous intensity IV:

The luminous intensity of a light-emitting diode usually refers to the luminous intensity in the direction of the normal line (for a cylindrical luminous tube, its axis). If the radiation intensity in this direction is (1/683) W/sr, it emits 1 candela (symbol is cd). Due to the low intensity of general LED light-emitting diodes, the luminous intensity is usually used as the unit of candlelight (candela, mcd).

5. The light-emitting angle of the LED:

-90°- +90°

6. Spectral half-width Δλ:

It represents the spectral purity of the luminous tube.

7. Half-value angle θ1/2 and viewing angle:

θ1/2 refers to the angle between the direction where the luminous intensity value is half of the axial intensity value and the luminous axis (normal direction).

8. Full form:

The angle calculated according to the solid angle of the seven segment LED light is also called the plane angle.