DLP391TPFSB datasheet(25/46 Pages) TI2

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Micromirror array temperature cannot be measured directly, therefore, it must be computed analytically from

measurement points on the outside of the package, the package thermal resistance, the electrical power, and

the illumination heat load. The relationship between array temperature and the reference ceramic temperature

(thermal test TP1 in Figure 6-2) is provided by the following equations:

TARRAY = TCERAMIC + (QARRAY × RARRAY-TO-CERAMIC)

QARRAY = QELECTRICAL + QILLUMINATION

where

• TARRAY = Computed array temperature (°C)

• TCERAMIC = Measured ceramic temperature (°C) (TP1 location)

• RARRAY-TO-CERAMIC = Thermal resistance of the package specified in Section 5.5 from array to ceramic TP1

(°C/Watt)

• QARRAY = Total (electrical + absorbed) DMD power on the array (Watts)

• QELECTRICAL = Nominal electrical power (Watts)

• QINCIDENT = Incident illumination optical power (Watts)

• DMD average thermal absorptivity = 0.54

• QILLUMINATION = (DMD average thermal absorptivity × QINCIDENT) (Watts)

The electrical power dissipation of the DMD is variable and depends on the voltages, data rates, and operating

frequencies. A nominal electrical power dissipation to use when calculating array temperature is 0.5W. The

absorbed power from the illumination source is variable and depends on the operating state of the micromirrors

and the intensity of the light source. The equations shown above are valid for a single-chip or multichip DMD

system. It assumes an illumination distribution of 83.7% on the active array and 16.3% on the active array

border.

The sample calculation for a typical projection application is as follows:

QINCIDENT = 12.1W (measured)

(1)

TCERAMIC = 53.0°C (measured)

(2)

QELECTRICAL = 0.5W

(3)

QARRAY = 0.5W + (0.54 × 12.1W) = 7.034W

(4)

TARRAY = 53.0°C + (7.034W × 2.3°C/W) = 69.2°C

(5)

6.7 Micromirror Power Density Calculation

The calculation of the optical power density of the illumination on the DMD in the different wavelength bands

uses the total measured optical power on the DMD, percent illumination overfill, area of the active array, and

ratio of the spectrum in the wavelength band of interest to the total spectral optical power.

• ILLUV = [OPUV-RATIO × QINCIDENT] × 1000mW/W ÷ AILL (mW/cm2)

• ILLVIS = [OPVIS-RATIO × QINCIDENT] ÷ AILL (W/cm2)

• ILLIR = [OPIR-RATIO × QINCIDENT] × 1000mW/W ÷ AILL (mW/cm2)

• ILLBLU = [OPBLU-RATIO × QINCIDENT] ÷ AILL (W/cm2)

• ILLBLU1 = [OPBLU1-RATIO × QINCIDENT] ÷ AILL (W/cm2)

• AILL = AARRAY ÷ (1 - OVILL) (cm2)

where:

• ILLUV = UV illumination power density on the DMD (mW/cm2)

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DLP391TP

DLPS289A – JUNE 2025 – REVISED SEPTEMBER 2025

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