Low voltage, high current boost converter IC

[Vinz_]

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 !

 

[Arouse1973]

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

 

[davenn]

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)

and will probably stop you finding a solution. components capable of carrying 10A are physically large

Dave

 

[Vinz_]

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

It does have to be only one battery.

and will probably stop you finding a solution. components capable of carrying 10A are physically large

Dave

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 ?

 

[davenn]

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 ?

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

 

[davenn]

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.

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

 

[Vinz_]

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 ?

 

[davenn]

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.

Voltage DOESNT flow

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

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 ?

yes, but as I said, for a very brief time

 

[BobK]

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]

yeah ... good plan B there Bob