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SID 2007 (San Diego, CA) Presentation

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This was the presentation I gave at SID 2007 event in San Diego, CA (October 2007)

This was the presentation I gave at SID 2007 event in San Diego, CA (October 2007)


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Transcript

  • 1. Remote LCD Buffer, Controller and Bridge An Engineering and Business Case for today’s mobile communication terminal Shri Sundaram, Toshiba America Electronic Components, Inc. Oct 2/3, 2007
  • 2. Background & Context
    • Market Trend
      • Shift to High Resolution: QVGA  WQVGA  WVGA
      • Several types of LCD mounting (mechanical): Cycloid, Slider, Clamshell etc.
    • Challenges posed by these trends
      • Power Consumption due to high speed refresh of large display resolutions
      • Data throughput (from Baseband or Application Processor to LCD Module)
    • Critical to overcoming these challenges
      • High-Speed and Large data transferability
      • Serial Data transferability with a fewest signal lines possible
      • Low EMI by, perhaps, Low amplitude signaling
      • High Capacity Buffer Memory is necessary
  • 3. Challenges posed by trends
  • 4. Challenges – Power Consumption
      • Power Consumption due to high speed refresh of large display resolutions
      • Data throughput (from Baseband or Application Processor to LCD Module)
    ~LCD refresh cycle Host CPU (Cellular BB) Application Engine Frame Buffer Memory Host CPU (Cellular BB) Application Engine Frame Buffer Memory Bridge LCDD RGB I/F LVDS I/F LVDS I/F LCDD WVGA WVGA Type 2 Type 1
  • 5. Challenges – Data Throughput
    • 30(Video codec rate)-60(Display refresh cycle) fps
    • WVGA = 800x480 pixels = 384,000 pixels
    • 18-24 bits per pixel
    • ---------------------------------------------------------------------------------------------------
    • Adds up to:
    • 207.36 Mbps – 552.96 Mbps!!!
      • Power Consumption due to high speed refresh of large display resolutions
      • Data throughput (from Baseband or Application Processor to LCD Module)
  • 6. Critical to overcoming these challenges
  • 7. Critical to overcoming these challenges – Buffer Memory Host CPU (Cellular BB) Application Engine Frame Buffer Memory Host CPU (Cellular BB) Application Engine Frame Buffer Memory LCD Buffer LCDD RGB I/F LVDS I/F LVS I/F LCDD LCD Buffer LVDS I/F ~ refresh cycle 15fps/30fps video codec ~ refresh cycle 15fps/30fps video codec WVGA WVGA
  • 8. Comparing the two cases! ~ refresh cycle Host CPU (Cellular BB) Application Engine Frame Buffer Memory Host CPU (Cellular BB) Application Engine Frame Buffer Memory Bridge LCDD RGB I/F LVDS I/F LVDS I/F LCDD WVGA WVGA Type 2 Type 1 Host CPU (Cellular BB) Application Engine Frame Buffer Memory Host CPU (Cellular BB) Application Engine Frame Buffer Memory LCD Buffer LCDD RGB I/F LVDS I/F LVS I/F LCDD LCD Buffer LVDS I/F ~ refresh cycle 15fps/30fps video codec ~ refresh cycle 15fps/30fps video codec WVGA WVGA Main Difference
  • 9. What difference does a Frame Buffer IC make?
    • The main issue
      • Application Engine does Video decoding and LCD controlling functions
      • Often, memory on Application Engine is non-dedicated memory for Video operation and Frame buffering
      • Even for a simple image refresh (@30fps), Application Engine cannot go to sleep mode!
    • The concern is
      • Dependence on the memory usage (size of image) PLUS the need to refresh main LCD and/or sub-LCD makes this system consume high-power
  • 10. The Need for Display Buffer WVGA Display BB w/ QVGA RAM (for video and screen saver) no RAM!! WVGA Buffer BB Cost Power/ Performance RAM WVGA Display (Performance) (Cost???)
  • 11. Business case?
    • Using LCD Frame Buffer IC brings into focus certain tangible financial benefits and some intangible financial benefits.
    • Financial Benefits
      • No need for a frame buffer on the LCD Driver (use of so called “Dumb Displays”)
      • No need for frame buffer on the Application Processor
    • Intangible Benefits
      • Lower power consumption means longer battery life!
      • Certain “smartness” can be configured into the LCD Buffer IC such as…
        • Scaling (or) doubling function
        • Partial Writing
        • Image Inversion
        • Rendering 18 bit data in pseudo 24 bit format
        • Etc…
  • 12. LCD Buffer Basic Configuration (actual product)
    • Video Data is input as Serial (LVDS) and Output as Parallel (RGB)
    LCD Buffer Memory for VGA/WVGA PLL LCD Controller Core Logic LVDS I/F 30fps ~Refresh rate RGB Data VSYNC HSYNC Dot Clock Reference Clock LVDS
  • 13. In Summary
    • There is a trend toward higher resolution displays in mobile phones
      • While these trends bring fascinating applications to consumers, it does makes the job of system engineers difficult.
    • Two major problems
      • Power consumption
      • Data throughput
    • LCD Buffer IC is solution to these problems
  • 14. Something to think about…
    • LCD Buffer IC may not be suitable for lower resolution displays since the economics may weigh in favor of LCD Driver with integrated RAM
    • However, it may be wise to consider including LCD Buffer ICs in the platform to allow for future upgrades to higher resolution designs
  • 15.