What are the general LED terminology?

Date:2022-3-9 Category:Industry News

The following are common LED terminology:

Forward operating current IF: It refers to the forward current value when the light emitting diode emits light normally. In actual use, IF should be chosen to be below 0.6ifm.

Forward operating voltage VF: The operating voltage given in the parameter table is obtained with a given forward current. Typically measured at IF = 20mA. The light emitting diode forward operating voltage VF is in the range of 1.4-3v. When the outside temperature increases, VF will drop.

V-I characteristics: The relationship between the voltage and current of the light emitting diode. After the forward voltage is less than a certain value, the forward current increases rapidly with the voltage and emits light.

Luminous intensity IV: The emitted intensity of a light-emitting diode usually refers to the luminous intensity in the direction of a normal line (for the axis of a cylindrical light-emitting tube). If the radiation intensity in this direction is (1/683) W/sr, then 1 candela is emitted (sign bit cd). Since the general LED has low intensity of light emission, the luminous intensity is often measured by candela (mcd).
The light emitting angle of the LED: -90° - +90°.

Spectral half width △in: It represents the spectral purity of the luminous tube.
Half-value angle 1/2 and viewing angle: 1/2 refers to the angle between the direction in which the luminous intensity value is half of the axial strength value and the luminous axis (normal direction).

Full shape: The angle converted from the LED light solid angle. Also called the plane angle.

Perspective: The maximum angle at which the LED emits light. According to the different perspectives, the application is also different, also called light intensity angle.

Half shape: angle between normal 0° and maximum luminous intensity value/2. Strictly speaking, it is the angle between the maximum luminous intensity value and the maximum luminous intensity value/2. The LED packaging technology causes the maximum light emission angle not to be a normal 0° light intensity value, and introduces a deviation angle, which refers to the angle between the maximum luminous intensity corresponding angle and the normal 0° angle.

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

Maximum reverse current VRm: the maximum reverse voltage allowed, beyond which the light emitting diode may be damaged by breakdown.

Work environment topm: The ambient temperature range in which the LED can operate normally. Below or above this temperature range, the light emitting diode will not work properly and the efficiency will be greatly reduced.

Permissible power consumption Pm: The maximum value allowed to be added to the positive dc voltage across the LED and the current flowing through it. Above this value, the LED is hot and damaged.
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