understanding led’s 1
DESCRIPTION
Basic Terms used in picking the correct LEDTRANSCRIPT
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Picking the Correct LED Picking the Correct LED for your designfor your design
by: Philip Levickby: Philip Levick
March 17March 17thth, 2009, 2009
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Overview
Applications for LED’s
Advantages of LED’s
Basic physics behind LED’s
Important terms when picking LED’s
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Applications for LED’sApplications for LED’sSigns
Transportation
Personal Electronics
Lighting
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Advantages to LED’sAdvantages to LED’sPower SavingsPower Savings
Lower HeatLower Heat Incandescent ≈ 17Incandescent ≈ 17m/Wm/W LED ≈ 100LED ≈ 100m/Wm/W
LifeLife Incandescent ≈ 1000hrs.Incandescent ≈ 1000hrs. LED ≈ 50,000hrs.LED ≈ 50,000hrs.
Small form factorSmall form factor
DurabilityDurability
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Basic Physics behind LED’sBasic Physics behind LED’s
Semiconductor materials are picked
Electrons and Holes are excited by a forward Current
Electrons and holes are combined Excess energy is emitted as photons
The distance the electron falls determines the wavelength
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Basic Physics behind LED’sBasic Physics behind LED’s
Hole Electron
P-Type N-Type
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
What are the different parts of What are the different parts of the LED?the LED?
Anode
Lead
Frame
Semiconductor
Epoxy Case
Cathode
Wire Bond
Reflector
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Important Definitions
Luminous Flux Measure of power perceived by the eye
Units = lumens (lm) = cd * 1 steradian Steradian
Spherical Area
Luminous Intensity The measure of wavelength emitted power by
a light source in the visible spectrumUnits = candela (cd)
Viewing Angle Angle at which the light is 50% intensity
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Definitions in motion
Viewing Angle = Max Luminous Intensity (cd) * 50%
Luminous intensity = Point source of lightLuminous Flux = Sensitivity to the human eye
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Power Angle
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
How do I choose the LED color?How do I choose the LED color?
Chromaticity diagram
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Chromaticity for a white LED
Chromaticity diagram for white LED
Coordinates for color ranking
b1
b2
a0
c0
X=0.3
Y=0.3
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Summary
Applications for LED’s
Advantages of LED’s
Basic physics of the LED
Important terms when picking LED’s
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
References
LEDlight.com
Nichia.com
Wikipedia.com
Howstuffworks.com
Led.linear1.org
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Questions
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
Backup
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
What color is my LED?What color is my LED?
04/10/2304/10/23 Phil Levick - Understanding LED'sPhil Levick - Understanding LED's
b1
b2
a0
c0
X=0.3
Y=0.3