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TLV758P: Ferrite Bead & Capacitor selection guidance

Neet
Intellectual 532 points
Part Number: TLV758P

Hello Community,

We are designing a solution where we need both 3.3V & 5V supply from a single power source.

We have decided to install 2 different LDOs (TLV758P) for 3.3V & 5V supplies.

We want to install Ferrite beads for isolating noise above 10Mhz. Kindly guide us with relevant application notes, reference designs or key pointers that will help us make correct design decisions about Ferrite bead selection & placement around capacitors.

Also, suggest the optimum placement for the Ferrite beads & accompanying capacitor in the following configuration.

Your guidance is highly appreciated.

Regards

  • 0
    TI__Mastermind 18466 points

    Hey Neet, 

    Do you know the exact frequency disturbances you'll be seeing?

    You would want to pick a ferrite bead that acts closest to a resistor at the frequencies you are trying to eliminate. 

    As for specific capacitor decisions, You would have to look at the ESR value of the crossover frequency of the capacitor. You would want the crossover frequency to land where the you see the most noise disturbance is, along  with where the PSRR dips in your application/board layout. 

    Murrata has simulations on their website to help visualize this

    In the past we were able to run transistor level sims, but the team no longer has the bandwidth for that. 

    Best,

    Juliette