DLP391TPFSB datasheet(28/46 Pages) TI2

28 / 46 page

Length of the window aperture for critical area = 0.9802cm (data sheet)

(9)

Width of critical area = 0.050 cm (data sheet)

(10)

AAP-ILL = 0.9802cm × 0.050 cm = 0.04901cm2

(11)

QAP-ILL = (12.1W × 0.00312) ÷ (0.04901cm2 × 0.25) = 3.08W/cm2 (W/cm2)

(12)

6.9 Micromirror Landed-On/Landed-Off Duty Cycle

6.9.1 Definition of Micromirror Landed-On/Landed-Off Duty Cycle

The micromirror landed-on/landed-off duty cycle (landed duty cycle) denotes the percentage of time that an

individual micromirror is landed in the ON state versus the amount of time the same micromirror is landed in the

OFF state.

For example, a landed duty cycle of 100/0 indicates that the referenced pixel is in the ON state 100% of the time

(and in the OFF state 0% of the time); whereas 0/100 would indicate that the pixel is in the OFF state 100% of

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

Note that when assessing the landed duty cycle, the time spent switching from one state (ON or OFF) to the

other state (OFF or ON) 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)

always add to 100.

6.9.2 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 DMD micromirror array (also called the active array) to an asymmetric landed

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

Note that it is the symmetry/asymmetry of the landed duty cycle that is of relevance. 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.

6.9.3 Landed Duty Cycle and Operational DMD Temperature

Operational DMD temperature and landed duty cycle interact to affect DMD useful life, and this interaction can

be exploited to reduce the impact that an asymmetrical landed duty cycle has on the DMD's useful life. This is

quantified in the derating curve shown in the Recommended Operating Conditions. The importance of this curve

is that:

• All points along this curve represent the same useful life.

• All points above this curve represent a lower useful life (and the further away from the curve, the lower the

useful life).

• All points below this curve represent a higher useful life (and the further away from the curve, the higher the

useful life).

This curve specifies the maximum operating DMD temperature that the DMD should be operated at for a given

long-term average landed duty cycle.

6.9.4 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 follows from the image content being

displayed by that pixel.

For example, in the simplest case, when displaying pure-white on a given pixel for a given time period, that pixel

operates under a 100/0 landed duty cycle during that time period. Likewise, when displaying pure-black, the pixel

operates under a 0/100 landed duty cycle.

DLP391TP

DLPS289A – JUNE 2025 – REVISED SEPTEMBER 2025

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