DLPS188B September   2021  – March 2024 DLP780NE

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  Storage Conditions
    3. 5.3  ESD Ratings
    4. 5.4  Recommended Operating Conditions
    5.     11
    6. 5.5  Thermal Information
    7. 5.6  Electrical Characteristics
    8. 5.7  Timing Requirements
    9.     15
    10. 5.8  System Mounting Interface Loads
    11.     17
    12. 5.9  Micromirror Array Physical Characteristics
    13.     19
    14. 5.10 Micromirror Array Optical Characteristics
    15.     21
    16. 5.11 Window Characteristics
    17. 5.12 Chipset Component Usage Specification
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Power Interface
      2. 6.3.2 Timing
    4. 6.4 Device Functional Modes
    5. 6.5 Optical Interface and System Image Quality Considerations
      1. 6.5.1 Numerical Aperture and Stray Light Control
      2. 6.5.2 Pupil Match
      3. 6.5.3 Illumination Overfill
    6. 6.6 Micromirror Array Temperature Calculation
    7. 6.7 Micromirror Power Density Calculation
    8. 6.8 Window Aperture Illumination Overfill Calculation
    9. 6.9 Micromirror Landed-On/Landed-Off Duty Cycle
      1. 6.9.1 Definition of Micromirror Landed-On/Landed-Off Duty Cycle
      2. 6.9.2 Landed Duty Cycle and Useful Life of the DMD
      3. 6.9.3 Landed Duty Cycle and Operational DMD Temperature
      4. 6.9.4 Estimating the Long-Term Average Landed Duty Cycle of a Product or Application
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Temperature Sensor Diode
  9. 8 Power Supply Recommendations
    1. 8.1 DMD Power Supply Requirements
    2. 8.2 DMD Power Supply Power-Up Procedure
    3. 8.3 DMD Power Supply Power-Down Procedure
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
      1. 9.2.1 Layers
      2. 9.2.2 Impedance Requirements
      3. 9.2.3 Trace Width, Spacing
        1. 9.2.3.1 Voltage Signals
  11. 10Device and Documentation Support
    1. 10.1 Third-Party Products Disclaimer
    2. 10.2 Device Support
      1. 10.2.1 Device Nomenclature
    3. 10.3 Device Markings
    4. 10.4 Documentation Support
      1. 10.4.1 Related Documentation
    5. 10.5 Receiving Notification of Documentation Updates
    6. 10.6 Support Resources
    7. 10.7 Trademarks
    8. 10.8 Electrostatic Discharge Caution
    9. 10.9 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

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.

Between the two extremes (ignoring for the moment color and any image processing that may be applied to an incoming image), the landed duty cycle tracks one-to-one with the gray scale value, as shown in Table 6-1.

Table 6-1 Grayscale Value and Landed Duty Cycle
GRAYSCALE VALUELANDED DUTY CYCLE
0%0/100
10%10/90
20%20/80
30%30/70
40%40/60
50%50/50
60%60/40
70%70/30
80%80/20
90%90/10
100%100/0

Accounting for color rendition (but still ignoring image processing) requires knowing both the color intensity (from 0% to 100%) for each constituent primary color (red, green, and blue) for the given pixel as well as the color cycle time for each primary color, where “color cycle time” is the total percentage of the frame time that a given primary must be displayed in order to achieve the desired white point.

Use Equation 29 to calculate the landed duty cycle of a given pixel during a given time period.

Equation 29. Landed Duty Cycle = (Red_Cycle_% × Red_Scale_Value) + (Green_Cycle_% × Green_Scale_Value)
+ (Blue_Cycle_% × Blue_Scale_Value)

where

  • Red_Cycle_% represents the percentage of the frame time that red is displayed to achieve the desired white point.
  • Green_Cycle_% represents the percentage of the frame time that green is displayed to achieve the desired white point.
  • Blue_Cycle_% represents the percentage of the frame time that blue is displayed to achieve the desired white point.

For example, assume that the red, green, and blue color cycle times are 30%, 50%, and 20% respectively (to achieve the desired white point), then the landed duty cycle for various combinations of red, green, blue color intensities are shown in Table 6-2 and Table 6-3.

Table 6-2 Example Landed Duty Cycle for Full-Color, Color Percentage
CYCLE PERCENTAGE
REDGREENBLUE
30%50%20%
Table 6-3 Example Landed Duty Cycle for Full-Color
SCALE VALUELANDED DUTY CYCLE
REDGREENBLUE
0%0%0%0/100
100%0%0%30/70
0%100%0%50/50
0%0%100%20/80
0%12%0%6/94
0%0%35%7/93
60%0%0%18/82
0%100%100%70/30
100%0%100%50/50
100%100%0%80/20
0%12%35%13/87
60%0%35%25/75
60%12%0%24/76
100%100%100%100/0

The last factor to account for in estimating the landed duty cycle is any applied image processing. Within the DLPC4430 display controller, the gamma function affects the landed duty cycle.

Gamma is a power function of the form Output_Level = A × Input_LevelGamma, where A is a scaling factor that is typically set to 1.

In the DLPC4430 display controller, gamma is applied to the incoming image data on a pixel-by-pixel basis. A typical gamma factor is 2.2, which transforms the incoming data as shown in Figure 6-3.

GUID-E965F171-6172-4502-91CF-3D4D5ED85EDF-low.gif Figure 6-3 Example of Gamma = 2.2

From Figure 6-3, if the gray scale value of a given input pixel is 40% (before gamma is applied), then gray scale value is 13% after gamma is applied. Therefore, it can be seen that since gamma has a direct impact displayed gray scale level of a pixel, it also has a direct impact on the landed duty cycle of a pixel.

Consideration must also be given to any image processing that occurs before the DLPC4430 display controller.