<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Michael, <div><br></div><div>Thanks for taking a look at the power supply thread, as my projects run on batteries, I have put some time into this.</div><div><br></div><div>Here are a few thoughts:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- Like you, my circuits draw a relatively small amount of current. I developed these tests at a higher current so they would not take a month to run</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- your current regulator (<a href="http://ww1.microchip.com/downloads/en/DeviceDoc/20001826C.pdf">MCP1700-3302E</a>) is Linear so it will dissipate - read waste - power equal to the product of the difference between Vin and Vout time current (Eqn 6-1 in data sheet)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- This is where I started but I decided to move to a switched power supply for three reasons:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- They are battery omnivores - since the <a href="http://www.ti.com/lit/ds/symlink/tps63030.pdf">TPS63031</a> is both boost and buck and is over 90% efficient over a large range (1.8-5.5Vin) - I can throw all sorts of batteries at it</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- As they are more efficient, they should throw off less heat - potentially a big deal since I put them in a box and bury them</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- This supply can handle from very small 25uA to 800mA currents</div><div><br></div><div>As with all things in Engineering, there are some trade-offs I had to accept:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- more expensive</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- QFN packaging - ugh</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- weird and exotic new component required - an inductor - no really! There are a bewildering number of choices here!</div><div><br></div><div>Some suggestions:</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- I would be happy to loan you my test rig which you could use to test your current power supply and compare it to the three I made. </div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- I added the Excel spreadsheet with the full set of tests and results to the posting on the <a href="http://triembed.org/blog/?page_id=234">Triembed.org</a> site</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- I could give you a TPS63031 breakout board so you could test the supply in your circuit without the pain of soldering - I have some extras</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- You could look at commercial options such as the little breakout boards from Pololu - I have <a href="http://www.pololu.com/product/2122">one of these you could borrow</a> if you like</div><div><br></div><div>Hope this helps. </div><div><br></div><div>BTW, my next step in my power supply obsession is to add a battery fuel gauge to the circuit so my Arduino can check it and so I could use LiPO batteries with more confidence.</div><div><br></div><div><br></div><div>Chip</div><div><br></div><div><br></div><div><br><div><div>On Sep 16, 2014, at 5:00 PM, <a href="mailto:triembed-request@triembed.org">triembed-request@triembed.org</a> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">MCP1700-3302E</span></blockquote></div><br></div></body></html>