LED Junction Temperature
LED junction temperature is the highest operating temperature of the actual semiconductor in an LED device. In operation, it is higher than case temperature and the temperature of the part’s exterior. The difference is equal to the amount of heat transferred from the junction to case multiplied by the junction-to-case thermal resistance.
RC (Resistance-Capacitance) driver is just a simple LED driver mode. It actually through RC buck rectifies a 220V AC power to a certain DC voltage. It is a rough and unstable, less demanding driver. RC driver is cheap but less efficient, it will lead to the LED decay quickly, even burned.
‘Isolated’ refers to a circuit separated from the AC line in order to prevent electric shock. Isolated power supply has a power output that is electrically independent of its power input. This type of power supply is safe but less efficient.
A non-isolated circuit is one not shielded from the AC power source, which makes electrocution possible. This type of design is mainly for double-insulated products, such as LED replacements for bulbs, in which the LED and the whole product are integrated and sealed in the non-conductive plastic, making the light fixture safe. Usually, the driver … Continue reading Non-isolated Driver
Constant Voltage Driver
Constant Current Driver
With constant-current drivers power (Usually 350mA, 700mA and 1A) LEDs require a fixed output current while the voltage output will vary depending on the load. The more LEDs are attached, the higher the output voltage will be, up to a maximum set by the driver. This type of driver is usually used when the load/number … Continue reading Constant Current Driver
LED Driver Efficiency
LED driver efficiency is the ratio of the power delivered from the driver divided by the power required to operate the driver. It describes how much of the power drawn by the power supply is lost in heat. A highly efficient driver dissipates less heat and allows for easier thermal management to stabilize the design … Continue reading LED Driver Efficiency
Thermal Resistance is an indication of how effectively a unit rids itself of heat. Thermal resistance for an LED is used to determine the difference in temp between the package (heat slug) and the die.
LED Lumen Depreciation
Transmittance refers to the ratio of the intensity of incident light to the intensity of transmitted light. It is a measurement of how much light passes through a substance. The higher the amount of light that passes through, the larger the transmittance.
Luminaire Failure Analysis
Solid-State Lighting refers to a type of lighting that uses semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas.
PCB (Printed Circuit Board)
LED Heat Sink
LED Luminaire Reliability
LED Light Colors
Light Distribution Curves
The curves provide information about the way light is distributed from the fixture and also how that light falls upon a surface.
LED Bonding Wire
Gold bonding wire is used in one of LED packaging processes, the wire bonding process, to provide electrical interconnection between the LED chip and lead frame.
Nowadays, due to the high price of gold wire, some LED manufactures are using copper wire or even low performance alloy wire as alternative. However, compared to gold wire, copper is significantly more prone to corrosion issues, besides,
Glare refers to the visual discomfort and visibility dropping which is due to the inappropriate brightness distribution, or to the extreme brightness contrast in space or time. The glare can be caused directly by the light source, or the light reflected from a surface.
A component of the LED driver, with function to offer high capacitance value on to the circuit board. Many people argue that the electrolytic capacitor is the bottleneck factor of LED lights.
Correlated Color Temperature(CCT)
A measure of the color of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (K). It characterizes how the white light looks. For instance, if the light goes more blueish, it would have a “cool” temperature, and if it’s more reddish, it would be “warm” in temperature.
Color Rendering Index (CRI)
A measure of the quality of color light. To help determine how well lights reproduce color, bulbs are given a CRI score between zero and 100. This score represents a comparison between the spectrum of colors the light produces and the spectrum naturally produced by the sun in the same color temperature. For example,