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DLP5533A-Q1: Toggle default State of 10 Pixel Boarder

Will Rusin
Prodigy 10 points
Part Number: DLP5533A-Q1
Other Parts Discussed in Thread: STRIKE

Tool/software:

We have designed a custom board in a target projection system using the DLP5533A-Q1.  We mistakenly designed the chip mechanically rolled 180 deg.  This has caused us to invert the on/off state of each pixel to correctly display our patterns, which is working fine.  However, the 10 pixel boarder that is by default off and apparently not addressable, are effectively in the on state for our rolled configuration.  I.E. we project a bright boarder instead of a dark boarder.  We are hoping there is a way to toggle the state of the entire boarder from the always off state to always on.

We are really under the gun, so any help would be greatly appreciated. 

Thanks,

Will 

  • 0
    TI__Guru 52695 points

    Will, 

    Regrettably there is no way to change the state of the border pixels.  They are permanently set to "off" by circuitry in the DMD and are not addressable.  The only solution I can think of is to very carefully adjust your overfill to not strike these pixels and set the 10 pixels on the border of the active array to "on" to be off in your setup.  I realize that this will sacrifice 20 pixels in each direction of the resolution.  You might be able to get away with less than 10, but that will depend upon your optical design.

    Fizix

  • 0
    TI__Expert 6430 points

    Hi Will,

    I'm very sorry to hear about your predicament, but I'm afraid there is not anything that we can do to change the state of the Pond of Mirrors (PoM) that surrounds the DMD. As you have hinted at reading from the datasheet, "The structure and qualities of the border around the active array includes a band of partially functional micromirrors called the POM. These micromirrors are structurally and/or electrically prevented from tilting toward the bright or ON state, but still require an electrical bias to tilt toward OFF."

    I talked with the optics team here, and the consensus is that a respin is your only option, as I assume the timeframe to redesign your optics is not enough?

    For future reference, here is an example from the DLP5533-Q1 datasheet that shows how these S450 DMDs are illuminated:

    Mechanical ICD drawings are also available on the product page (DLPR072 - DMD Mounting Design) to aid any further development.

    Regrettably, the short answer is you must respin your board. 

    As you may already know, DMDs will require an overfill in order to have uniform light across the active mirror array. This means the POM will always be illuminated so that we have this uniformity. Because the DMD is flipped 180 degrees, contrast will take a hit due to the POM always being "ON" in this case. If you do not require the full DMD active area, you could possibly use a larger aperture, but again, contrast will take a hit, and your usable area shrinks.

    For redesigning, I have been unable to see any immediate symmetry you may take advantage of. I'm very sorry...
    Please be sure to follow the layout guidelines for your respin in section 10 of the datasheet.
    I'd also like to leave a tip that large power planes for V_offset, V_reset, and V_bias are strongly recommended. This is something that has been an issue in the past for some customers, so it I figured I would make a point here on that.

    Regards,
    Michael Ly