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Same IC, Different Temperature?

FCS found the interesting phenomenon during this week’s test.
 
1. There is unequal heat distribution on LED High-Bay’s housing

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M1 (Point 1 on the housing): 49.1°C
 
M2 (Point 2 on the housing): 43.8°C
 
M1 > M2 (more than 6°C)
 
But why there is unequal temperature on the housing. Let’s open the lamp and check.

2. “Quad-Core-Driver”
 
The sample is a 200W LED High-Bay. For lamp’s stable working, the engineer provided 4-ways power supply for the LEDs.

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It’s an economic solution for the driver for high power LED lamps. People combine small wattage LED driver for the application of high wattage LED lamps. e.g. 200W LED Lamp has 4x50W LED Drivers. However, this kinds of solution has its own weakness, as the coin has two sides, we have to find out their balance.
 
The temperatures are quite different between components by thermal imagery.
 
Put it closer.

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There are four ICs (Same Model, Same Supplier)
 
M1(IC-1):99.6°C
 
M2(IC-2):100.5°C
 
M3(IC-3):93.5°C
 
M4(IC-4):88.0°C
 
The temperature difference between ICs are more than 10°C, even some kinds of IC is able for working under more than 105°C, even still there is margins to the limitation. But lamp’s life will be effected and reduces if keep working in high temperature.

3 Think about the “Air” & “Glue”
 
And which is the reason to cause such kind of difference inside the lamp? Let’s check the structure.

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Following are conjectures by our studies:
 
-Driver’s location cause different temperature between ICs directly.
 
-There is chimney effect between the hole in the middle of the lamp and outside environment. Hot air comes out from the hold and make the ICs near the hold having higher temperature than others.
 
-The diver’s housing is connected with lamp’s body by strong glue. The glue may insulate driver’s components from high temperature.

We are 3rd party testing & inspection.
 
Whatsapp: +86 18616827523
 
Wechat: LNY0539
 
E-mail: info@skdindustry.com

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