# ultra low dc-dc boost converter

Discussion in 'The Projects Forum' started by JNG44, Dec 19, 2013.

1. ### JNG44 Thread Starter New Member

Dec 19, 2013
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Hi i am looking to design a solar cell powered dc-dc boost converter and i am having difficulty finding recent infomation on the latest technology and the issues in this field of power electronics... can anyone please assist?

2. ### wayneh Expert

Sep 9, 2010
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Take a look at the IC manufacturers such as Linear and International Rectifier. They'll have products in this area and may also have pre-commercial, experimental "products" they will share.

3. ### BobTPH Active Member

Jun 5, 2013
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TI also has a lot of good DC-DC converter chips.

Bob

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4. ### JNG44 Thread Starter New Member

Dec 19, 2013
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Thanks for your help, i'll look into it. Do you know the most efficient way to boost 0.3v to 3v? I have looked on digikey and read a few power electronic books which gave some ideas how to simulate several designs on multisim but it only stepped up to 0.5v?

5. ### BobTPH Active Member

Jun 5, 2013
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A Joule Thief circuit might operate as low as .3V, but I am not sure. That is a very low voltage to start with, I don't know of any boost converter chips that go down that low. You might want to look up "energy havesting".

Bob

6. ### Papabravo Expert

Feb 24, 2006
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The price for boosting the voltage by a factor of 10 is lowering the current output, at 3 volts, by a factor of more than 10. In simple terms your first "back-of-the-envelope" calculation is that "Power In" is required to be "Power Out" DIVIDED by the Efficiency. Efficiency of a DC-DC converter will ALWAYS be a number in the interval [0, 1). In particular, the efficiency can NEVER be equal to 1.

Example: You want 3V @ 100 milliwatts. That is a current of 33.3... milliamperes. So far so good. Assume a DC-DC converter exists that has an 80% efficiency. So 100 milliwatts / .8 = 125 milliwatts. Still with me? So 125 milliwatts at 0.3 V requires a current of -- are you ready? -- ≈ 417 milliamperes. So finally we see that 417 milliamperes / 33.3 milliamperes ≈ 12.51, and unless I missed something 12.51 is > 10 period, full stop.

Now the question of weather you can build a DC-DC converter that will work down to 0.3V remains to be seen.

7. ### JNG44 Thread Starter New Member

Dec 19, 2013
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Thanks Bob I will look into energy harvesting and the joule thief design.

Papa, that was a very interesting and helpful analysis of my problem at hand. I do have room to manoeuvre the input voltage up to 1 V and have researched different circuit designs, which do say 0.3 is too low.... Do you have an idea how to build an efficient circuit that will step up from 1 to 3-5v?

8. ### bance Member

Aug 11, 2012
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Shariar, did a pretty good video on this sort of thing!

HTH Steve

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9. ### BobTPH Active Member

Jun 5, 2013
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Your chances are much better at 1V. A Joule thief would operate pretty effectively at that level. At 0.3V, it would be very difficult to get any reasonable efficiency.

Bob

Nov 12, 2008
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12. ### The Electrician AAC Fanatic!

Oct 9, 2007
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The LTC3105 internal schematic shows a low voltage start-up block, but I don't see any such thing in the LTC3108 internals. How does it start up? With only 20 mV input?

13. ### JNG44 Thread Starter New Member

Dec 19, 2013
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Thanks for the reply guys, especially loved the video.... Thanks again.

Energy Harvesting is something I have looked into and I would like to know who or where would be the best place to find the most up-to-date published articles on the topic. would it be manufacture websites or magazines.. etc?

14. ### BobTPH Active Member

Jun 5, 2013
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I take back my comment about not being able to get much efficiency at 0.3V input. Very cool.

Bob