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DLPC3433: DLPC3433

McQueen Hsieh
Prodigy 20 points
Part Number: DLPC3433

Hi~
1. if DMD_LS_CLK(120MHz)'s harmonic over FCC/CE's radiated emission limit value, any suggestion for this problem?


2. can i replace 43 ohm resistor to bead to reduce EMI problem?

  • 0
    TI__Expert 3905 points

    Hello McQueen,

    Welcome back to the E2E forum. Thank you for your continued business!

    We are looking into your two questions and will get back to you early next week with our response.

    Best,

    Maxine

  • 0
    TI__Intellectual 870 points

    Shielding is the typical solution for this type of issue. The shield can be a combination of the enclosure and/or routing the radiating signal on an inner layer with a solid plane above and below. I assume you have LS_CLK referenced to a solid GND plane.

    The 43 ohm series resistor placed close to the controller combines with the output impedance of the driver to match the impedance of the signal trace. Removing it is probably not a good idea. Adding a bead in series with the resistor will slow the rising and falling edges of the CLK which should help with radiated emissions. Most beads are rated at 100MHz and have steep rise in impedance with higher frequency. For this reason I do now believe adding one will work. You could try increasing the value of the series resistor.

    Please keep in mind that the integrity of the LS bus is critical. If it is corrupted the DMD can be permanently damaged. for this reason I suggest making small changes and verify the signal meets spec at the DMD.