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ADSP-21489 Power Sequence Schematic

Hi All,
I want to know how to design the ADSP-21489 Power Circuit simply,
and I want to know why the Time Delay device(ADM1085) is needed in the VDDINT circuit.

The DSP has a specific power-up sequence like as below.
- Power Up Sequencing Timing Requirements
  . VDDINT = VDDEXT +/- 200ms
  .
- ADSP-21489 Power Circuit
  . VDDEXT(3.3V@2A) -> Time.Delay(ADM1085) -> ADP1864(DCDC) -> VDDINT(1.1V@2A)
  . I think Time.Delay(ADM1085) doesn't need in the VDDINT power circuit, because VDDINT is VDDEXT +/- 200ms.
  . Can I remove the Time Delay Device(ADM1085)?
  . Why is the Time Delay device(ADM1085) needed in the VDDINT circuit?
  . Please share the simple VDDINT Power Circuit to be recommended if you have.
  . VDDINT Circuit
    :

Best Regards,
Eric.

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  • Hi Jithul,
    Thanks for your response.

    But I couldn't understand the below items exactly.
    Could you tell the meaning easily? (Sorry~)

    - I have to insert the ADM1085 for 35us delay or NOT.
    - What's the reason if I have to insert the ADM1085?
    - I don't know the exact meaning of the below contents.
      . Note that no power supply should be powered up for an extended period of time (> 200 ms) before another supply starts to ramp up.

    Best Regards,
    Eric.

Reply
  • Hi Jithul,
    Thanks for your response.

    But I couldn't understand the below items exactly.
    Could you tell the meaning easily? (Sorry~)

    - I have to insert the ADM1085 for 35us delay or NOT.
    - What's the reason if I have to insert the ADM1085?
    - I don't know the exact meaning of the below contents.
      . Note that no power supply should be powered up for an extended period of time (> 200 ms) before another supply starts to ramp up.

    Best Regards,
    Eric.

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