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DLPLCR4500EVM: Coil whine

Matteo Fissore
Prodigy 30 points
Part Number: DLPLCR4500EVM

Hello, I'm attempting to use a DLP4500EVM as board + chip only discarding the light engine. The board emits relatively loud (rough measurement using my phone is 75+ dB) and flat spectrum noise. I'm attaching a recording for reference as well.

Is this normal? If so, is there anything that can be done about this? 

Thank you.

  • 0
    TI__Genius 9570 points

    Hello Matteo Fissore,

    Welcome back to the E2E forums and we hope to assist you with your questions. 

    Please answer the following questions so we can better help debug this issue:

    1. So just for clarification this is currently a stock TI DLPLCR4500EVM with no changes to the hardware or software?
    2. Is there a certain operation or mode or specific pattern you are displaying that is causing this noise or are you seeing this issue on power up immediately?
    3. Are you able to narrow down the issue to a specific region or component? The reference design, schematics, and assembly drawing are here: https://www.ti.com/tool/DLP4500-C350REF 
    4. Please also try removing the fan cable connector J22 as this can contribute to noise of the system overall. Do you still hear anything after the fan is disabled? I tested this in our lab and the system is very quiet once I disabled the fan. 

                

            5. Are you using the recommended power supply with correct current and voltage ratings?

                

    Regards,

    Alex Chan

  • 0 in reply to Alexander Chan
    Prodigy 30 points

    Hello, thank you for your reply.

    1. This is a TI DLPLCR4500EVM where the only changes are that the LED cables have been disconnected and the optical engine removed, however the DMD remains on the flex attached to the board. No other HW or software modifications.

    2. The noise starts immediately on power up

    3. It would seem the noise is concentrated on the backside of the board near where the inductors are.

    4. Yes, this is the exact model 

    KTPS90-1207 Kaga Electronics USA | Power Supplies - External/Internal (Off-Board) | DigiKey

    I have tested the board with another 12 V, 10 A power supply and the results are identical.

  • +1 in reply to Matteo Fissore
    TI__Genius 9570 points

    Hello Matteo Fissore,

    Thanks for the information.

    You also confirmed that the noise is not due to the fan correct?

    If you try changing the LED currrent values to lower through the GUI does that change the noise?

    Regards,

    Alex Chan

  • 0 in reply to Alexander Chan
    TI__Genius 9570 points

    Hello Matteo Fissore,

    I will be closing this thread due to inactivity. If you have any further questions or comments, please start a new E2E thread.

    Thanks,

    Alex Chan