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USB Power

Discussion in 'General Electronics Discussion' started by Delphawi, Sep 4, 2012.

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  1. Delphawi

    Delphawi

    3
    0
    Sep 4, 2012
    Hello

    I need to connect some (or all) of three components I have to a Laptop USB port to use it as a power for the circuit . The power specifications for them are the following:
    First one DC12V , 0.18A
    Second one DC05V , 0.17A
    Third one DC12V , 0.14A

    How can I use the USB power to make my circuit work ? how many components I can run using a single USB cable ?

    Thanks in advance
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    That is a total power of 4.7W. A USB 2.0 port can supply only 2.5W and a USB 3.0 port can supply only 4.5W. So you are out of luck even at 100% efficiency for converting the 5V power to 12V.

    Bob
     
  3. Delphawi

    Delphawi

    3
    0
    Sep 4, 2012
    Thank you

    But how can I convert the 5V to 12V ?
     
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    You would use a DC-DC converter. But as I already explained, you cannot draw enough power from a USB port to power the devices you want.

    Bob
     
  5. Delphawi

    Delphawi

    3
    0
    Sep 4, 2012
    I guess I would use 1 or 2 of them only ..

    Thank you .
     
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