 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AN1149-4 Datasheet(PDF) 4 Page - Lumileds Lighting Company |
|
||||||||||||||||||||||||||||||
AN1149-4 Datasheet(HTML) 4 Page - Lumileds Lighting Company |
|
|
4 / 14 page  4 Thermal Modeling of LED Assemblies Thermal Resistance of LED Automotive Signal Lamps Thermal resistance is associated with the conduction of heat, just as electrical resistance is associated with the conduction of electricity. Defining resistance as the ratio of driving potential to the corresponding transfer rate, thermal resistance for conduction can be defined as shown in the equation below: _ Where: R θ = thermal resistance between two points ∆T = temperature difference between those two points q X = rate of heat transfer between those two points The thermal resistance of an LED signal lamp (junctiontoambient thermal resistance, or Rθ ja ) is made up of two primary components: the thermal resistance of the LED package (junctiontopin thermal resistance, or Rθ jp ) and the thermal resistance of the lamp housing (pin toambient thermal resistance, or Rθ pa ). These two components of thermal resistance are in a series configuration, therefore: Rθ jp + Rθ pa = Rθ ja (LED emitter) (lamp housing) (LED signal lamp) This is shown graphically in Figure 4.3. Assuming all the electrical power is dissipated in the form of heat (approximately 5to10% of the power is dissipated optically), the equation for junctiontopin thermal resistance (Rθ jp) of an LED can be written in the form of the equation below: Where: P = the total electrical power into the LED (I f * Vf) For LED lamp assemblies, the equation for junction toambient thermal resistance, Rθ ja, of an individual LED within the assembly can be written as: Where T j = ∆Tj + Ta . As can be seen from this equation, in order to determine Rθ ja of an LED within a lamp assembly, the rise in junction temperature, and the electrical power into the device must be determined. The electrical power into the LED under test can easily be determined by multiplying its forward current and forward voltage. The rise in junction temperature can be determined by measuring the change in forward voltage of the LED under test. Figure 4.3 Graphic representation of the components of thermal resistance. |
Similar Part No. - AN1149-4 |
|
Similar Description - AN1149-4 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
