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DS90UB954-Q1: Ferrite beads option of VDD18

Tomoaki Yoshida91
Genius 5255 points
Part Number: DS90UB954-Q1


Hi team,

We will design the circuit with reference to the typical application in the data sheet.

It seems that the 1.8V ferrite bead changes depending on whether the 1.1V power supply is generated by an internal regulator or supplied externally.

When supplying from the outside, three ferrite beads are inserted in each 1.8V power line, but when using the internal regulator, it seems that only one ferrite bead can be used.

Why is there a difference?

When using it in the internal regulator mode, the ferrite beads that are optional are for CSI and FPD, and I think that there is no correlation with the 1.1V power supply.

How should we determine if we need FB2 or FB3 in this mode?

Best regards,

Tomoaki Yoshida

  • 0
    TI__Guru** 103215 points

    Hello Tomoaki,

    I think this may actually be a typo - the 1.8V rails recommendations should not change based on the 1.1V internal or external supply configuration. FB2 and FB3 should always be optional based on system supply noise levels.

    If your power supply can ensure that the voltage at each of these pins meets the specified supply noise levels (50mVpp from DC to 50MHz), without ferrite beads then it is ok to remove them. 

    Best Regards,

    Casey