Datasheet
DLP5500
DLPS013E –APRIL 2010–REVISED SEPTEMBER 2013
www.ti.com
Micromirror Array Temperature Calculation for Uniform Illumination
Micromirror array temperature cannot be measured directly; therefore it must be computed analytically from
measurement points ( Figure 13), the package thermal resistance, the electrical power, and the illumination heat
load. The relationship between micromirror array temperature and the case temperature are provided by the
following equations:
T
Array
= T
Ceramic
+ (Q
Array
x R
Array-To-Ceramic
)
Q
Array
= Q
ELE
+ Q
ILL
Where the following elements are defined as:
T
Array
= computed micromirror array temperature (°C)
T
Ceramic
= Ceramic temperature (°C) (TC2 Location Figure 13)
Q
Array
= Total DMD array power (electrical + absorbed) (measured in Watts)
R
Array-To-Ceramic
= thermal resistance of DMD package from array to TC2 (°C/Watt) (see Package Thermal
Resistance)
Q
ELE
= Nominal electrical power (Watts)
Q
ILL
= Absorbed illumination energy (Watts)
An example calculation is provided below based on a traditional DLP Video projection system. The electrical
power dissipation of the DMD is variable and depends on the voltages, data rates, and operating frequencies.
The nominal electrical power dissipation to be used in the calculation is 2.0 Watts. Thus, Q
ELE
= 2.0 Watts. The
absorbed power from the illumination source is variable and depends on the operating state of the mirrors and
the intensity of the light source. Based on modeling and measured data from DLP projection system
Q
ILL
= C
L2W
x SL.
Where:
C
L2W
is a Lumens to Watts constant, and can be estimated at 0.00274 Watt/Lumen
SL = Screen Lumens nominally measured to be 2000 lumens
Qarray = 2.0 + (0.00274 x 2000) = 7.48 watts, Estimated total power on micromirror Array
T
Ceramic
= 55°C, assumed system measurement
Finally, T
Array
(micromirror active array temperature) is
T
Array
= 55°C + (7.48 watts x 0.6 ° C/watt) = 59.5°C
For additional explanation of DMD Mechanical and Thermal calculations and considerations please refer to DLP
Series-450 DMD and System Mounting Concepts (TI Literature number DLPA015).
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