Building multiple voltage sources

Discussion in 'General Electronics Chat' started by ericmar, Jun 10, 2008.

  1. ericmar

    Thread Starter New Member

    May 16, 2008
    6
    0
    Hi,

    I plan to use an AC adapter of +9V @ 2A as the main power source and step-up and step-down this power source to create few different voltage supplies (+12V, +3.3V and +1.8V).

    My problem is should I be stepping down the +1.8V from the main power source of +9V or stepping down from the regulated +3.3V (which is first step-down from the +9V). This is because the voltage difference between +3.3V and +1.8V is only +1.5V while the voltage difference between the +9V and +1.8V is as high as +7.2V. I think there will be waste of energy for such a conversion, right?

    How should I arrange it such that the power efficiency is optimum?

    Thanks for any help in advance.

    Regards,
    eric
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Switching Mode Power Supplies are very useful for efficiently implementing this type of power regulation.

    You would need one Boost-mode and two Buck-mode switching regulators.

    I assume you have looked at the total available power of 18 Watts and decided how you plan to divide that power up among the various supply outputs. Remember to take into account that you will only be able to depend on around 75% of the 18 Watts delivered to your load since each of the regulators will consume some power to achieve regulation.

    hgmjr
     
  3. ericmar

    Thread Starter New Member

    May 16, 2008
    6
    0
    Hi,

    Thanks for your reply.

    Yes. I understand that I will be needing one Boost-mode and two Buck-mode switching regulators. However, I am not sure if I should connect the input of my +1.8V Buck-mode switching regulator to the output of my +3.3V Buck-mode switching regulator rather than directly source from the AC adapter.

    Please advise. Thanks.


    Regards,
    eric
     
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