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Some chip beads between AM3358 and TPS65910A3 on TMDSSK3358

Nomo
Guru 16800 points
Other Parts Discussed in Thread: AM3358

Hello,

Why are there some chip beads between AM3358 and TPS65910A3 on TMDSSK3358?
I'm checking the TMDSSK3358 schematics, and the chip beads are on the right hand (such as FB9) of AM3358 in page 4.

Best Regards.

Nomoto

  • 0
    TI__Guru**** 393215 points

    Hi Nomoto-san,

    The ferrite beads are not specifically required. Depending on layout they may be skipped, if there is a large power supply plane.

  • 0 in reply to Biser Gatchev-XID
    TI__Guru 62855 points

    Typically ferrite beads are used to create a local low-pass filter on each power domain when separate power domains are being sourced from a common power supply.  By inserting a low-pass filter on each power domain, any noise generated from one power domain must pass through two low-pass filters (one as it propagates back up to the main power source and another as it propagates down to the other power domains) before it interferes with other power domains.

    The decision to use ferrite beads is based on many system variables like power supply design, PCB layout, quality of decoupling capacitors, other power supply noise sources including external noise sources, etc.  Therefore, it is the system designers responsibility to insure the power supply noise is acceptable for the product to operate over all expected use cases.

    Regards,
    Paul