(°C/W)

• DMD average thermal absortivity = 0.40

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 0.1 W. 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 each DMD chip in a system. It

assumes illumination distribution of 83.7% on the active array and 16.3% on the area outside the array.

(3)

(4)

(5)

(6)

(7)

7.7 Micromirror Landed-On/Landed-Off Duty Cycle

7.7.1 Definition of Micromirror Landed-On and Landed-Off Duty Cycle

The micromirror landed-on/landed-off duty cycle (landed duty cycle) denotes the amount of time (as a

percentage) that an individual micromirror is landed in the ON state versus the amount of time the same

micromirror is landed in the OFF state.

As an example, a landed duty cycle of 75/25 indicates that the referenced pixel is in the ON state 75% of the

time (and in the OFF state 25% of the time), whereas 25/75 indicates that the pixel is in the OFF state 75% of

the time. Likewise, 50/50 indicates that the pixel is ON 50% of the time and OFF 50% of the time.

When assessing landed duty cycle, the time spent switching from the current state to the opposite state is

considered negligible and is thus ignored.

Because a micromirror can only be landed in one state or the other (ON or OFF), the two numbers (percentages)

nominally add to 100.In practice, image processing algorithms in the DLP chipset can result a total of less that

100.

7.7.2 Landed Duty Cycle and Useful Life of the DMD

Knowing the long-term average landed duty cycle (of the end product or application) is important because

subjecting all (or a portion) of the micromirror array (also called the active array) to an asymmetric landed duty

cycle for a prolonged period of time can reduce the usable life of the DMD.

The symmetry of the landed duty cycle is determined by how close the two numbers (percentages) are to being

equal. For example, a landed duty cycle of 50/50 is perfectly symmetrical whereas a landed duty cycle of 100/0

or 0/100 is perfectly asymmetrical.

7.7.3 Landed Duty Cycle and Operational DMD Temperature

Operational DMD temperature and landed duty cycle interact to affect the usable life of the DMD. This interaction

can be used to reduce the impact that an asymmetrical landed duty cycle has on the useable life of the DMD.

7.7.4 Estimating the Long-Term Average Landed Duty Cycle of a Product or Application

During a given period of time, the landed duty cycle of a given pixel depends on the image content being

displayed by that pixel. To enhance reliability, when coupled with the DLPC1438 controller, the DLP300S DMD

operates at a maximum 78/22 duty cycle and a minimum of 22/78 duty cycle.

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DLP300S

DLPS214A – JULY 2021 – REVISED AUGUST 2021

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