powering from 1.5v...


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  1. #1
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    Default powering from 1.5v...

    Hello,

    Just wandering if anyone ever did a project that require powering from a single 1.5v battery like the one used in watches or wall clock.
    Just wandering how they manage to get the device working from 1.5v or do they use a boost converter to 5v. If so how is the boost converter made. I looked into my wrist watch and could not see any coil or obvious boost up converter of any kind..

    K

  2. #2
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    Default Re: powering from 1.5v...

    MAX1674, MAX1675, MAX1676 ; High-Efficiency, Low-Supply-Current, Compact, Step-Up DC-DC Converters

    http://www.maxim-ic.com/datasheet/index.mvp/id/1878


    http://circuitschematic.blogspot.com/2010/07/15v-to-5v-converter-circuit.html
    Last edited by sayzer; - 15th November 2011 at 10:00.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

  3. #3
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    Default Re: powering from 1.5v...

    Why use an extra chip when you already have a pic?! Here's a rather ingenious way to run a controller off a single cell!

    http://spritesmods.com/?art=ucboost&page=2

    Hope it helps.

    Regards,

    Anand Dhuru

  4. #4
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    Default Re: powering from 1.5v...

    Quote Originally Posted by lerameur View Post
    Hello,

    Just wandering if anyone ever did a project that require powering from a single 1.5v battery like the one used in watches or wall clock.
    Just wandering how they manage to get the device working from 1.5v or do they use a boost converter to 5v. If so how is the boost converter made. I looked into my wrist watch and could not see any coil or obvious boost up converter of any kind..

    K
    Do you want to use a coin cell battery? Why don't you use a 3.0 volts lithium coin cell battery?

    Robert
    "No one is completely worthless. They can always serve as a bad example."

    Anonymous

  5. #5
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    Default Re: powering from 1.5v...

    I want to keep the price as low as possible. Lithium batteries are very expensive compared to round alkaline battery. but even at 3v, it does not leave much space for its lifespan , no ? when it falls just .5v then its game over.. i guess, I could be wrong.

  6. #6
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    Default Re: powering from 1.5v...

    I have heard that Lithium batteries have a flat discharge. A coin cell may last longer a 3 volts than several alkaline at 1.5. The alkaline will start showing a voltage drop as soon as it is used.
    Dave
    Always wear safety glasses while programming.

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    Default Re: powering from 1.5v...

    Quote Originally Posted by lerameur View Post
    I want to keep the price as low as possible. Lithium batteries are very expensive compared to round alkaline battery. but even at 3v, it does not leave much space for its lifespan , no ? when it falls just .5v then its game over.. i guess, I could be wrong.
    Many chips minimum operating voltage is at 1.8V, so I don't see any problem. Check out this application note about the coin cell lifetime.

    http://www.maxim-ic.com/app-notes/index.mvp/id/505

    Robert
    "No one is completely worthless. They can always serve as a bad example."

    Anonymous

  8. #8
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    Default Re: powering from 1.5v...

    Quote Originally Posted by lerameur View Post
    Lithium batteries are very expensive compared to round alkaline battery. .
    Really? Here in my city a CR2032 costs about 20 cents US, and thats retail. The cheapest alkaline would be at least twice as much.

  9. #9
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    Default Re: powering from 1.5v...

    Forget coin and costs. Here is the final solution:

    http://www.microchip.com/wwwproducts...cName=en548192

    http://www.microchip.com/wwwproducts...cName=en548193

    These chips will drain every mV from your battery untill is very very dead!

    Ioannis

  10. #10
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    Default Re: powering from 1.5v...

    Quote Originally Posted by mackrackit View Post
    I have heard that Lithium batteries have a flat discharge.
    Dave,

    Thanks. That is good to know for future design reference. According to the app note that I mentioned above the discharge rate of these Lithium batteries is pretty flat.

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    "No one is completely worthless. They can always serve as a bad example."

    Anonymous

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