buck boost/sepic-powered usb

Discussion in 'The Projects Forum' started by sampath312, Nov 10, 2010.

  1. sampath312

    Thread Starter New Member

    Nov 10, 2010
    hi dear friends..

    Im looking for some knowledge regarding a project I'm engaged in, relevant to power supply.

    main aim of my project is to design a varaible voltage regulator which can be used with powered usb ports(usb pluspower) here are the basic specifications

    input- 12V @ 3A (from poweredUSB port)
    output voltage-5V to 30V (variable)
    output current-1A all through out the range

    I was first planing to use a buck-boost/cuk converter as output voltage is less or greater depending on the required output..But sepic topology seems to be like more straight forward as the polarity is not inverted...

    So have you guys got any better idea or if you got any knowledge relevant to this kind of a project ur support is highly appreciated...

    From basic reading what i understood was most of the times both these topologies are used to give a steady output when input is varying within a certain range..so I doubt how applicable those 2 topologies in to this perticular project..ur ideas are more than wellcomed.

    thanks in advance...
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Have you gone over the specs for USB3 (still a bit vaporware-ish). This is from a USB3 FAQ -
    1000 ma is a long way from 3 amps. I'm not sure that the voltage isn't the standard 5 VDC.
  3. magnethead


    Nov 9, 2010
    yes, USB3 is still only a 5 volt rail that I'm aware of, to keep in proper reverse compatiability with legacy devices.
  4. retched

    AAC Fanatic!

    Dec 5, 2009
    Usb PLUS POWER is 12v or 24v depending on which flavor you wish.

    It is basicially like power over ethernet, but using USB ;)

    It is, I believe a 6 wire system. The standard 4 wire usb, then 12v+(or 24v) and an additional power GND

    ok, here is the standard:

    And I was wrong, it is an 8 wire system ;)
    Last edited: Nov 10, 2010
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    Great Another connector to keep a supply of. :mad:
  6. magnethead


    Nov 9, 2010
    that makes 2 of us.... and I thought power-over-eSATA was getting overzealous....
  7. sampath312

    Thread Starter New Member

    Nov 10, 2010

    first of all thanks for participating to the thread with ur valuable ideas...

    well i think usb3 is not providing enough power :(...at the high end the device should able to prove 30V @ 1A so (30W) but usb3 is well below that limit (5V @ 1amp) so powered usb will be the only option as far as i can see:rolleyes: which gives 12v supply @ 3A current (36W>30W)

    so what about toplogies..have you guys got any ideas about ic s supporting sepic topologies..:confused: this is one of them i ve been reading these days..TPS61170 ..But i dobt if i can use it in the reverse manner..I meant typical applcation of this is totake a steady output when input is varying withing a range( as battery power drains slowly).But Im trying to do opposite use the same topology to increase and decrease the output when input stay inside a steady level..

    ......................................I-->30V @ 1amp[out]
    in 12v @ 3A--(sepic)--->I
    ......................................I-->5V @ 1amp[out]

    if you guys know any other chips that you think worth looking in to please mention and im more than willing to look in to the applicability of them:)

    thanks again...