Post Go back to editing

Questions about Power circuit design of ADRV9026/ADRV9029 using Feritte beads

Hello,

My customer decides to use ADRV9026 in their system.

So they are reviewing your reference schematic now.

During reviewing ADRV9026 EVM schematic, they found many beads are used in this schematic.

So they want to get your advices about using  Feritte beads in power circuit.

Q1) In your EVM schematic, All  power pins of ADRV9026 are attached to Feritte beads . ( Used  Feritte bead per each pin.)

      Should they use all Feritte beads in your EVM schematic?

     Please refer below pictures in your EVM schematic (P.8~P.9).

2)  If they should use all Feritte beads like above pictures, would you explain why they use use these Feritte beads?

3) If they can't use Feritte beads, could you suggest guide line of using Feritte beads  and advices about designing power circuit of ADRV9026?

Please let me know.

Regards,

Se-woong

Parents
  • Q1: Yes, it is recommended to use all ferrite beads as per the EVM schematic.

    Q2: The use of ferrite beads is to filter high frequency power supply noise and cleanly sharing similar supply rails.

    Q3: Not sure if i understand your question correctly. The ferrite beads is must and they will have low DC resistance with the supported load current and they will have high impedance at high frequencies. One such example for a ferrite bead is BLM21PG220SN1D from Murata. Attached an app note on the Ferrite beads uses.

    PDF

Reply
  • Q1: Yes, it is recommended to use all ferrite beads as per the EVM schematic.

    Q2: The use of ferrite beads is to filter high frequency power supply noise and cleanly sharing similar supply rails.

    Q3: Not sure if i understand your question correctly. The ferrite beads is must and they will have low DC resistance with the supported load current and they will have high impedance at high frequencies. One such example for a ferrite bead is BLM21PG220SN1D from Murata. Attached an app note on the Ferrite beads uses.

    PDF

Children
  • Dear Ramarao

    Thank you for your prompt reply.

    I have additional questions about your answer.

    My customer says that the board size isn't  a big enough to use all ferrite  beads.

    So if you can recommend, would you let use know essential points that  ferrite  bead should be used?

    In other words, could you suggest your opinions reducing a number of ferrite beads?

    Please advise me.

    Regards,

    Se-woong

  • Please refer : UG 1727, Table 251. Power Supply Pins and Functions.

    We have defined which pins are sensitive to aggressors and you can keep ferrite beads for those.

    Other its mentioned as use ferrite beads if necessary. In this case,  may be you can give provision and do not mount in first design.

    Custom boards have other components on same board and chances of noise getting coupled are more compared to evaluation boards. So you need to take care for same in your design.