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Original question:

TLC5973: about emc test

TLC5973: EMC emission problems

Joost DN
Prodigy 30 points
Part Number: TLC5973

We are experiencing the exact same problem as described in this post.
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/957582/tlc5973-about-emc-test

Several peaks at multiples of ±12MHz.
Even when there is no communication towards the led drivers, when all leds are off. Only a (stable) 5V power supply to the TLC5973 is enough to produce this emission.
Are there already any recommendations on how to resolve these EMC issues?
On the graph below, the green line is the radiation with many TLC5973 led drivers in a chain (each on a separate PCB). The blue graph is with only one TLC5973 connected.

I have tried the proposed solution with the addition of capacitors on the output signals.
I have tried inserting ferrite beads and pi filters (Murata Emifil) on the power line.
None of the attempts had any significant impact.

  • 0
    TI__Genius 12915 points

    Hi Joost,

    This is an existing issue that caused by internal 12MHz GS clock, which would be enhanced by cascading several ICs. Then we need to find the high frequency loop path and the antenna to reduce the radiation. Could you help to share your schematic and test environment?