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+/- supply frm single chip

Discussion in 'Electronic Basics' started by [email protected], Aug 19, 2006.

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  1. Guest

    i m doin 1 project where i need 2 supply power 2 ADC AD677 ... i need
    +/- 5/12 volts..i want this all frm single chip instead of using
    7805,7812,7905 & 7912.

    can u help me
     
  2. Eeyore

    Eeyore Guest

    What's the big deal about using '1 chip' only ?

    Graham
     
  3. John Fields

    John Fields Guest

     
  4. Eeyore

    Eeyore Guest

    There are some single chip twin rail ICs but they're quite expensive and not
    widely available. I'm trying to find out the underlying reason for the question
    so as to be able to give a decent answer.

    Graham
     
  5. PeteS

    PeteS Guest

    What's Vin?

    Cheers

    PeteS
     
  6. John Fields

    John Fields Guest

    ---
    The big deal is, that's what he wants, and a decent answer, you rude
    piece of shit, might have been: "I don't think what you want is
    available, but there are some single chip twin rail ICs which are
    quite expensive and not widely available. Is there any reason why
    you can't use conventional supplies?
     
  7. Eeyore

    Eeyore Guest

    Still doesn't answer why he's so keen t use a single chip though. Really also need
    to know what the proposed power source is. As in is it necessasry to creat a 'false
    ground'.

    To be honest *any* further information at all would be useful.

    Got out the wrong side of bad today did you btw ?

    Graham

    p.s. what's your feeling about the terror con being foisted on the public ?
     
  8. Chris

    Chris Guest

    In order to get a more helpful answer, you have to tell what you've got
    as an input voltage, and how much power you need for the other stuff.

    I'm also wondering where your requirement for -5VDC is coming from --
    the AD677 only requires a +5 for logic and a +/-12V for the analog
    side.

    Apart from all that, no single IC exists that can do what you want.
    Linear regulators are cheap and efficient -- splurge a little. But if
    you want maximum simplicity or absolute minimum space, try purchasing a
    small AC-to-DC converter which will give you the three voltages.

    And please hold off on the text lingo unless you're kidnapped and are
    being confined in a car trunk. It gives the impression you can't even
    be bothered to express yourself clearly. That's not a good impression
    to give if you're asking for someone to craft a ldetailed, cogent
    answer.

    Good luck
    Chris
     
  9. Guest

    Vin is 20 V...and i hv been told 2 use a single chip...i can use the
    above mentioned chips..but i hv 2 use a single chip which is a cheap 1
    too...
     
  10. John Fields

    John Fields Guest

     
  11. Eeyore

    Eeyore Guest

    AC or DC ? With or without centre tap ?
    There is no cheap single chip solution to your problem I'm afraid.

    Please answer the above about the AC or DC input too.

    Graahm
     
  12. Chris

    Chris Guest

    The only way you're going to get from a +20V to +5V and +/-12V outputs
    with one component is with a DC-to-DC converter.

    Look at this from Jameco:

    http://tinyurl.com/km54w

    Their P/N 217648CM is a MeanWell (and I'm sure you do) DC-to-DC
    converter with triple output. This is a rather expensive one part
    solution to your problem.

    If you want cheap, you'll have to consider going with more than one
    component. For a low current requirement, I'd think the lowest cost
    solution *is* a 7812 and 7805, with a small switcher to convert the
    +20V to -12V.

    If you want more help, you'll also have to mention your total power
    requirements for each power source (i.e. how much current do you need?)

    Good luck
    Chris
     
  13. Tim Auton

    Tim Auton Guest

    y u hv 2 us jst 1 chp chp? :(
    btw ur 4 7xxx chps wnt wrk - u nd n nvrtr 2 2 gt -V frm +V.

    u cn lk @ Mxm. thy hv mltpl otpt dc-dc chps. Mxm cn smtms b 2 hrd 2 by
    frm if u r nt v v bg cmpny.

    http://www.maxim-ic.com/products/power/dc_dc_switchers/


    Tim, getting down with the kids.
     
  14. PeteS

    PeteS Guest

    I could actually understand that. Perhaps I should list it as a
    language skill on my CV ;)

    Cheers

    PeteS
     
  15. Eeyore

    Eeyore Guest

    Wicked !

    Graham
     
  16. Chris

    Chris Guest

    Mad props, Tim. U got skillz. ;-)

    Cheers
    Chris
     
  17. Tim Auton

    Tim Auton Guest

    Simply pull the waitband of your trousers half-way down your arse-cheeks
    and typing that way will come naturally to you too. I think the nerves
    corresponding to the vowels must be located at the top of the gluteus
    maximums and sensitive to cold.


    Tim
     
  18. Eeyore

    Eeyore Guest

    He wants dual-dual though !

    Graham
     
  19. Jamie

    Jamie Guest

    you need a DC-DC converter chip with +&- out..
    look at mouser, Digikey etc...
    they have Dual output types
     
  20. Guest

    why sir???dnt we hv any chip for this ??
     
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