[Noisebridge-discuss] driving multiple LEDs with minimal batteries

Jonathan Foote jtfoote at ieee.org
Fri Jan 7 18:28:37 PST 2011


On Thu, Jan 6, 2011 at 5:11 AM, Christoph Maier
<cm.hardware.software.elsewhere at gmail.com> wrote:
> On Wed, 2011-01-05 at 21:30 -0800, T wrote:
>> > Now, what's all this SEPIC stuff, anyways?
>>
>> SEPIC is a particular type DC-DC converter such as buck, boost,
>> buck-boost, can cuk
>>
>> http://en.wikipedia.org/wiki/SEPIC
>
> SEPIC is what Dr. Foote calls a boost converter
> http://en.wikipedia.org/wiki/Boost_converter
> in last November's Five Minutes of Fame,
> http://www.ustream.tv/recorded/10946425 ,
> beginning at about 49 1/2 minutes.
> (Can anyone, by any chance, post the slides somewhere,
> Nudge nudge. Nudge nudge. Know what I mean?)


Hint taken:
https://docs.google.com/present/edit?id=0ASCtknwltXrAZHQ1OG5yMl8zMDVmaDltMjRnNQ&hl=en&authkey=CNO7t6sK


> Unlike the two-component solution
> [ http://www.diodes.com/datasheets/ZXSC380.pdf
> page 1, "Typical application circuit",
> and page 6, "Application Notes", Fig. 2],
> with a current regulation and efficiency that is so-so
> [see the graphs on page 3],
>
> Jonathan draws some serious power,
> so he needs a little more than 2 components,
> probably even more than the 5 components in Fig. 5,
> to control current and efficiency more accurately
> than the ZXSC380, which is more optimized for blinkenlights
> (well, ok, 200kHz blinkenlights,
> so it looks continuous to the human eye)
> running off a single 1.5V-ish battery.

That looks like an awesome chip. Hey Meredith, consider it for your
next Starboard fab.


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