# Important parameters of LED chips

- Mar 20, 2019-

1. Forward working current If:

It refers to the forward current value when the light-emitting diode is normally illuminated. In actual use, the IF should be selected below 0.6·IFm as needed.

2. Forward working voltage VF:

The operating voltages given in the parameter table are obtained at a given forward current. It is generally measured at IF = 20 mA. The forward working voltage VF of the light-emitting diode is 1.4 to 3V. As the outside temperature rises, the VF will drop.

3.V-I features:

The relationship between the voltage and current of the light-emitting diode is such that when the forward voltage is less than a certain value (called a threshold), the current is extremely small and does not emit light. When the voltage exceeds a certain value, the forward current rapidly increases with the voltage and illuminates.

4. Luminous intensity IV:

The luminous intensity of the light-emitting diode generally refers to the luminous intensity in the direction of the normal line (for the axis of the cylindrical light-emitting tube). If the radiation intensity in this direction is (1/683) W/sr, then the light can be 1 candela (symbol cd). Since the intensity of the LED of a general LED is small, the intensity of the illumination is usually a candle (candela, mcd).

5. LED illumination angle:

-90°- +90°

6. Spectral half width Δλ:

It represents the spectral purity of the arc tube.

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

θ 1/2 means an angle between the direction in which the luminous intensity value is half of the axial intensity value and the axial direction of the light emission (normal direction).

8. Full shape:

The angle converted from the solid angle of the LED illumination is also called the plane angle.

9. Perspective:

Refers to the maximum angle of LED illumination, depending on the viewing angle, the application is also different, also called the light intensity angle.

10. Half shape:

The angle between the normal 0° and the maximum luminous intensity value/2. Strictly speaking, it is the angle corresponding to the maximum luminous intensity value and the maximum luminous intensity value of /2. The LED packaging technology results in the maximum illumination angle not being the normal 0° intensity value, and the introduction of the deviation angle refers to the angle between the angle corresponding to the maximum illumination intensity and the normal 0°.

11. Maximum forward DC current IFm:

The maximum forward DC current allowed to be applied. Exceeding this value can damage the diode.

12. Maximum reverse voltage VRm:

The maximum reverse voltage allowed to be applied is the breakdown voltage. Above this value, the light-emitting diode may be damaged by breakdown.

13. Working environment topm:

The ambient temperature range in which the LED can operate normally. Below or above this temperature range, the LED will not work properly and the efficiency will be greatly reduced.

14. Allow power consumption Pm:

The maximum value of the product of the forward DC voltage applied across the LED and the current flowing through it. Above this value, the LED is hot and damaged.