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DLP7000: Questions regarding mirror clock pulse

Pete Zhou
Prodigy 20 points
Part Number: DLP7000
Other Parts Discussed in Thread: DLPA200, DLPC410

Tool/software:

I have a few questions regarding the mirror clock pulses (MCP) that are sent to update the physical state of mirrors in each block for the DLP7000. When I measure the mirror clock pulse directly, I get the following signal:

Is there a particular reason for this two-step behavior? Does this have something to do with the mirror clock pulse shape varying based on DMD chip type as referenced in the documentation for the DLPA200 DMD Micromirror Driver?

Furthermore, the documentation for the DLPA200 mentions that  "the Micromirror Clock Generation function uses the three voltages generated by the High-Voltage Power Supply function to create the sixteen micromirror clock pluses" with those three voltages being V_BIAS, V_RESET, and V_OFFSET. How exactly are they combined to produce the MCP?  

  • 0
    TI__Guru 54705 points

    Hello Pete,

    This waveform is correct other than the ringing at the transitions (likely due to incorrect termination impedance on the probes).

    For the DLPC410 platform this waveform is generated by the DLP200 [https://www.ti.com/product/DLPA200].

    The two step behavior is required to cause mirrors whose underlying CMOS data has changed to cross over to the other side while also allowing those mirrors whose data has not changed to remain on the same side.  In other words a crossover is {1->0] or [0->1] and a stay transition is [1->1] or [0->0].

    Fizix

  • 0 in reply to Fizix
    Prodigy 20 points

    Thank you for the response! So if I understand this correctly, there are different voltage thresholds for crossover transitions (i.e. where the digital state has changed) and for stay transitions (i.e. where the digital state has remained the same)? Does this imply that if a one-step pulse sent, then only crossover transitions or only stay transitions will occur, depending on the voltage level? 

  • 0 in reply to Pete Zhou
    TI__Guru 54705 points

    Pete

    It is the same waveform for all pixels.  Beyond this we are not at liberty to say but only to note that it is required for the pixels to work correctly.

    Fiizx