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DLP6500FYE: Noise while operating the DMD

Peihang Xu
Prodigy 95 points
Part Number: DLP6500FYE
Other Parts Discussed in Thread: TPS65145

Hello there,

We are currently using a DLP6500FYE DMD with DLPLC6500EVM to drive it. We found that when we were displaying images on the DMD, we could hear some high pitch noise coming from DMD. The pitch of the noise would also change with different images displayed. Do you think the noise is normal? Any suggestions?

Thank you very much,

Peihang

  • 0
    TI__Guru 54705 points
    Hello Peihang,

    Can you (without touching the DMD board during operation) determine if the noise is from the DMD itself or the PMIC (Power Management IC - TPS65145)?

    Is the DMD displaying correctly? Is the noise only noticeable in a quiet environment or quite noticeable even with other equipment (cooling fans, etc . . . ) running?
  • 0 in reply to Fizix
    Prodigy 95 points
    Hello Fizix,

    What is the PMIC? I am not too sure about whether he noise is from DMD itself or PMIC. But the noise is from the red PCB where the DMD is located.

    The DMD displays correctly, and the noise is definitely noticeable.

    Best,
    Peihang
  • 0 in reply to Peihang Xu
    TI__Guru 54705 points

    Hello Peihang,

    The "PMIC" is outlined in green and the nearby inductor in magenta in the image below:


    You can use a small piece of rubber or vinyl tubing about 5mm in diameter and hold one end to your ear opening and the other end near (but not touching) these two components during operation to see if the sound is coming from them.

    If so, then let the system run for a bit and completely power down.  Then (using a static protection strap) feel these components and the DMD to see if one or more of them is getting very hot.  

    If so, then there is a chance that the DMD has become electrically damaged.

    Fizix

  • 0 in reply to Fizix
    Prodigy 95 points

    Hi Fizix,

    Thank you for your instruction. I think the noise is from DMD mirror itself instead of the PMIC. And the PMIC is not hot after the operation. What would you suggest?

    Best,

    Peihang

  • 0 in reply to Peihang Xu
    TI__Guru 54705 points
    Peihang,

    Is the DMD getting hot?

    Fizix
  • 0 in reply to Fizix
    Prodigy 95 points
    Hi Fizix,

    It is not hot, just a little bit warm, but I think it should be okay.

    Peihang
  • 0 in reply to Peihang Xu
    TI__Guru 54705 points

    Hello Peihang,

    As long as the components (PMIC, DMD, & Inductor) are not getting hot then there should not be an issue.  We have had a few EVM boards here that "sing" a little.  It is almost certainly the PMIC/Inductor circuitry as the DMD produces no oscillations in audible frequencies.

    If one or several of the components were getting very hot that could suggest a short, but it appears that it is not.

    Fizix