Glossary

AC

AC stands for Alternating Current, as is a term used to describe the nature of the voltage/current flowing in a circuit. AC is commonly used for halogen lighting, and 230V AC - 240V AC is the supply in all New Zealand households that are connected to the national grid.

Anode

The positive terminal of a diode. For a through hole LED this is the longer leg and the smaller terminal within the LED.

Candela

The candela is the SI base unit of luminous intensity. That is, power emitted by a light source in a particular direction. An ordinary wax candle generates one candela.

Cathode

The negative terminal of a diode. For a through hole LED this is the flat side on the lens and the larger terminal within the LED.

CCT

Correlated Colour Temperature, CCT rating is an indication of how "warm" or "cool" the light source appears. Warm white LEDs are typically 2800 - 3500K, while cool white is 6000 - 7000K. A blue tint appears above 7000K. The colour temperature for an LED is usually specified as a range.

Chip

The LED Die within the package is sometimes referred to as a Chip. The power of an individual LED is commonly increased by way of adding multiple chips within a single package. For example, many 5050 SMD LEDs have 3 chips within the one package, and LED flood lights can have more than 100 chips.

CRI

CRI is the quality of light and is represented by a number from 1 (worse) to 100 (best). A CRI of 100 means the light has the same quality as sunlight, it is pleasant and all colours look natural. If the CRI is below 50 the light has an unpleasant feel and colours look unnatural (for example, skin appears less pink).

DC

DC stands for Direct Current, and is a term used to describe the nature of the voltage/current flowing in a circuit. DC is supplied from a Power Supply as it puts out a constant voltage, and is common in low voltage applications. Many LED products require a DC voltage (12V or 24V) such as LED Strip Lighting, LED Modules etc.

Die

LEDs are actually much smaller than the package they are sold in. They consist of a small amount of semiconductor material called a Die which is mounted in a package for the ease of handling, mounting and thermal conductivity. The LED die is sometimes referred to as a Chip.

Driver

A driver is an electronic device that outputs a constant current, required for directly driving high power LED chips such as the CREE XR-E series. The term Driver should not be confused with a Power Supply or Transformer, as it has a very different function. Common output values for a driver are 350mA, 700mA and 1A, however other values can be used within an LED product.

LED

LED stands for Light Emitting Diode and it is an electronic semiconductor component. If current flows through the diode, light is emitted with a wavelength that depends on the semiconductor material.

Lumens

A lumen is a unit of standard measurement used to describe how much light is contained in a certain area. The best way to compare the total brightness for LED products is to compare their lumen outputs.

Lux

Lux is lumen per square meter. The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. 1000 lumens, concentrated into an area of one square meter, lights up that square meter with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square meters, produces a dimmer illuminance of only 100 lux.

Power Supply

A power supply is often used to power low voltage LED products such as LED Strip Lighting, MR16 Bulbs etc. A power supply outputs a DC voltage which is required by many of these LED products and should not be confused with a Transformer or Driver.

SMD

SMD stands for Surface Mount Device, and is a term used throughout electronic design of circuit boards etc. Many electronic components today are soldered onto pads on the surface of the circuit board, rather than having wires that protrude through the board. Many higher performing LEDs today are SMD, and they come in many package sizes such as 3528, 5050 and larger high power packages. The numbers relate to the dimensions in 10s of millimetres, for example 3528 is 3.5mm by 2.8mm.

Transformer

The term transformer is commonly used by electricians as they are used to halogen lighting. A transformer outputs an AC voltage which is required by many household halogen bulbs. Because electricians have been used to halogen lighting for so long, they often incorrectly use the term transformer when describing a Power Supply as well, which outputs a DC voltage.