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Low voltage, high current boost converter IC

Discussion in 'General Electronics Discussion' started by Vinz_, Feb 28, 2015.

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  1. Vinz_

    Vinz_

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    Feb 28, 2015
    Hi,

    I’m currently starting a project that may need high power drawing from a battery.
    First thing, the battery is a 18490 from AW, which nominal voltage is 3.7V. The battery runs from 4.2V at full charge to 2.5V when discharged. It is also capable of a continuous 18A draw.

    I need to draw at most 10A from this battery, but regulated at 5V (if possible, from 4.2V to 3V, I don't want the battery to discharge too much.).

    AND as I am quite a noob in electronics, I need your help finding an IC or whatever could allow me to achieve this.

    There’s however a restriction, this whole circuit must be small enough to fit on a 19mm in diameter circular board. (That's why it is so difficult to me to find a solution)

    Any help would be greatly appreciated !

    :)
     
  2. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    Wow your asking a lot. 10 Amps from a step up from worst case 3 Volts. Could you have two batteries in series, does it have to be 1 battery.
    Adam
     
  3. davenn

    davenn Moderator

    13,765
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    Sep 5, 2009
    and will probably stop you finding a solution. components capable of carrying 10A are physically large

    Dave
     
  4. Vinz_

    Vinz_

    3
    0
    Feb 28, 2015
    It does have to be only one battery.

    Aren't there any IC that will support any current, and that the current would be handled by some external component, like a transistor or something ?

    EDIT:
    If 10A is definitely not possible, would 5 or 6 be ?
     
    Last edited: Feb 28, 2015
  5. davenn

    davenn Moderator

    13,765
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    Sep 5, 2009
    yes there are lots, but just one on their own is bigger that your size restriction and there are still other components needed around it to make it work

    even for 5 - 6 Amps the same still applies
    If you want anything over around 3 -4 amps and up, you are going to have to reconsider your project size restrictions

    Dave
     
    Arouse1973 likes this.
  6. davenn

    davenn Moderator

    13,765
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    Sep 5, 2009
    And also this I didn't comment on
    That 18A would be for a pretty short time span .... maybe a few seconds or so

    actually doing a google search on that battery, you have seriously overestimated its capabilities
    they are a 1200mA/hr battery

    so tell us more about what you are trying to achieve

    cheers
    Dave
     
  7. Vinz_

    Vinz_

    3
    0
    Feb 28, 2015
    Well, I’m trying to flow a regulated voltage to a resistance (so it becomes hot). In a non regulated use, the value of this resistance determines the amps that are drawn from the battery.

    Concerning the battery, it is specified that the max continuous discharge rate is 18A, Also, the battery is a 15C so IIRC, 1200*15 = 18A. Am I right assuming this ?

    I came across another possible solution. Would it be possible to use a simple boost regulator, and then, when the current would be too high, pass it to a power transistor ? (But then, I think there would be heat problems...)

    Vincent

    EDIT:
    Would there be a way to use this on a single battery ? http://www.digikey.com/product-detail/en/OKR-T/10-W12-C/811-2180-ND/2199630
    I see it only accepts voltage >= 4.5V, is there still a way to use it ? Or would it be the same problem as earlier ?
     
    Last edited: Mar 1, 2015
  8. davenn

    davenn Moderator

    13,765
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    Sep 5, 2009
    Voltage DOESNT flow

    with the voltage regulated or not, the value of the resistance load still determines the current
    required from the PSU

    yes, but as I said, for a very brief time
     
  9. BobK

    BobK

    7,682
    1,687
    Jan 5, 2010
    And a boost converter at that kind of current is going to require a large inductor.

    If all you are doing is heating, why use a boost converter anyway? Why not use a heating element that works at the battery voltage? If it works at the low end of the battery voltage, you can use PWM to lower the output when the battery voltage is higher. This could be fairly small if you use a MOSFET that has very low on resistance.

    Bob
     
    davenn likes this.
  10. davenn

    davenn Moderator

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    Sep 5, 2009
    yeah ... good plan B there Bob :)
     
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