Datasheet
DLP4500
DLPS028A –APRIL 2013–REVISED MAY 2013
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Micromirror Array Temperature Calculation
Micromirror array temperature cannot be measured directly. Therefore, it must be computed analytically from:
Thermal test point location (See Test Point #1 in Figure 16 for FQE and Test Point #2 in Figure 17 for FQD)
Package thermal resistance
Electrical power dissipation
Illumination heat load
The relationship between the micromirror array and the reference ceramic temperature, Thermocouple Location
(Test Point #1 in Figure 16 for FQE and Test Point #2 in Figure 17 for FQD), is provided by the following
equations:
T
Array
= T
Ceramic
+ (Q
Array
× R
Array-To-Ceramic
)
Q
Array
= Q
Elec
+ Q
Illum
Q
Illum
= C
L2W
× SL
where the following elements are defined as:
T
Array
= computed micromirror array temperature (°C)
T
Ceramic
= ceramic case temperature (°C) (Test Point location)
Q
Array
= Total DMD array power (electrical + absorbed) (W)
R
Array-to-Ceramic
= thermal resistance of DMD package from array to TC3 (°C/W)
Q
Elec
= nominal electrical power (W)
Q
Illum
= absorbed illumination heat (W)
C
L2W
= Lumens-to-watts constant, estimated at 0.00293 watt/lumen, based on array characteristics. It
assumes a spectral efficiency of 300 lumens/watt for the projected light, illumination distribution of 83.7% on
the active array, and 16.3% on the array border and window aperture.
SL = measured screen lumens (lumens)
These equations are based on traditional 1-chip DLP system with a total projection efficiency from the DMD to
the screen of 87%. An example calculation for package FQE is provided below. DMD electrical power dissipation
varies and is dependent on the voltage, data rates, and operating frequencies. The nominal electrical power
dissipation used in this calculation is 0.25 watts. Screen lumens is 200 lumens. The ceramic case temperature at
Test Point #1 is 55°C. Using these values in the above equations, the following values are computed:
Q
Array
= Q
Elec
+ C
L2W
× SL = 0.25 W + (0.00293 W/Lumen × 200 Lumen) = 0.836 W
T
Array
= T
Ceramic
+ (Q
Array
x R
Array-To-Ceramic
) = 55 °C + (0.836 W × 2°C/W) = 56.67°C
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REVISION HISTORY
Changes from Original (April 2013) to Revision A Page
• Changed the device From: Preview To: Production ............................................................................................................. 1
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