Re: ADSP-21489 1.1V and 3.3V switching regulator options

Hello Mitesh

Sorry if I didn't make myself clearer. I am designing a new board from scratch so I am using some of the ideas from the EZ board. I was toying with the idea of using a 24V center tapped transformer supply (plus regulators) to drive both the analog and digital sections instead of a 5 Volt regulated supply.

If I use a 12 Volt supply to drive the 1.1V and 3.3V switching regulators would I have to increase the value of the 2.5uH switching inductors ??

regards

david

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  • Hi LucaV,

    The reason I take ADP1864 and the power sequencing control as a design reference is that its function and performance have been proven in ADSP-2148x EZ board. It is the first time for me to use switching regulator in PCB design. Because of the irreversibility of PCB, I wish to ensure that my design is sufficiently adequate by evaluating in different aspects.

    According to ADP2323 datasheet, it allows power sequencing applicable to DSP, which requires a power sequence between the core and the I/O voltages.  The core 1.1V and I/O 3.3V can be controlled to reach the final value at the same time (refer to Fig 45 at Rev. 0 | Page 17 of 32).

    So now, I believe that when ADP2323 switching regulator is used on ADSP-21489, there is no power sequencing issue. Right?

    Replacing two ADP1864 and a power sequencing circuit with one ADP2323 will help to reduce the PCB size and the regulator complexity. I also found that under the same settings, ADP2323 tool always gives a smaller conduct value than the ADP1864 tool.

    I would like to seek your help in following questions:

    • ADP1864 datasheet emphasizes that it is suitable for 1- to 3-cell Li-Ion battery-powered applications. From my understanding, I believe that there indicates a wider Vin voltage can be used in application. In contrast, does it mean that ADP2323 is an inferior choice for battery-powered switching regulator? My application uses the 9V Li-Ion battery, what is your recommendation for my design if I replace ADP1864 with ADP2323?
    • I found that a smaller Maximum Output Current results in a bigger inductor value by ADIsimPower. I cannot accurately estimate the maximum output current and always have to reserve a big safety margin. If I select IoutMax=2A while the real maximum output is 1A, is the design from ADIsimPower still acceptable?

    Thanks for your help.

Reply
  • Hi LucaV,

    The reason I take ADP1864 and the power sequencing control as a design reference is that its function and performance have been proven in ADSP-2148x EZ board. It is the first time for me to use switching regulator in PCB design. Because of the irreversibility of PCB, I wish to ensure that my design is sufficiently adequate by evaluating in different aspects.

    According to ADP2323 datasheet, it allows power sequencing applicable to DSP, which requires a power sequence between the core and the I/O voltages.  The core 1.1V and I/O 3.3V can be controlled to reach the final value at the same time (refer to Fig 45 at Rev. 0 | Page 17 of 32).

    So now, I believe that when ADP2323 switching regulator is used on ADSP-21489, there is no power sequencing issue. Right?

    Replacing two ADP1864 and a power sequencing circuit with one ADP2323 will help to reduce the PCB size and the regulator complexity. I also found that under the same settings, ADP2323 tool always gives a smaller conduct value than the ADP1864 tool.

    I would like to seek your help in following questions:

    • ADP1864 datasheet emphasizes that it is suitable for 1- to 3-cell Li-Ion battery-powered applications. From my understanding, I believe that there indicates a wider Vin voltage can be used in application. In contrast, does it mean that ADP2323 is an inferior choice for battery-powered switching regulator? My application uses the 9V Li-Ion battery, what is your recommendation for my design if I replace ADP1864 with ADP2323?
    • I found that a smaller Maximum Output Current results in a bigger inductor value by ADIsimPower. I cannot accurately estimate the maximum output current and always have to reserve a big safety margin. If I select IoutMax=2A while the real maximum output is 1A, is the design from ADIsimPower still acceptable?

    Thanks for your help.

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