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LMK03328: Sequence of VDDO at powering up from split-supply rails

Part Number: LMK03328

Hi,

Datasheet below shows sequence at powering up from split-supply rails.
In this Figure 86, it shows VDDO(1.8V) rise after VDD ≧2.72V.
Must VDDO(1.8V) rise after VDD ≧2.72V?

Best regards,
Shimizu

  • If VDDO is from a separate (split) supply from VDD, it is acceptable for VDDO to ramp at the same time as VDD, or for VDDO to ramp after VDD.  If VDDO_x ramps after VDD, then it is recommended for the PDN to go high after all VDD and VDDO_x pins have ramped.  Figure 86 shows how this could be done by having the PDN cap (Cpdn) to control the delay of the PDN rising edge.

    Alan

  • In reply to Alan O:

    Hi Alan,

    Is it acceptable for VDD rump after VDDO?

    Best regards,
    Shimizu
  • In reply to masahiko shimizu:

    I would not recommend that sequence.

    Alan

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