tag:blogger.com,1999:blog-4933229084436849167.post6998740474874031390..comments2013-07-16T18:21:13.708-07:00Comments on Ramblings of an E-Geek: Building Blocks: Switch Mode Power SupplyKenhttp://www.blogger.com/profile/02720825801825816765noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-4933229084436849167.post-88820962805901273842010-09-04T23:43:13.617-07:002010-09-04T23:43:13.617-07:00Thanks for sharing, I will bookmark and be back ag...Thanks for sharing, I will bookmark and be back again<br /><br /><a href="http://www.elcopelectronics.com" rel="nofollow">5v 12v 24v 48v SMPS Power Supply Circuit Adaptor | SMPS Battery Charger Manufacturers Products Exporters Suppliers</a>blackhttp://www.blogger.com/profile/12572617881140283084noreply@blogger.comtag:blogger.com,1999:blog-4933229084436849167.post-87108039365917003002010-08-30T20:16:24.350-07:002010-08-30T20:16:24.350-07:00@Alejandro
Thanks for your comment. I guess I ki...@Alejandro<br /><br />Thanks for your comment. I guess I kind of glossed over how I calculated the efficiency of of the LDO, but honestly that wasn't really the point of the post. You are correct in that you use input and output power as the common denominator for calculating efficiency. In the case of an LDO regulator, it is close enough to assume the current to be the same on both the input and the output, thus causing current to cancel out of the efficiency equation.<br /><br />Cheers!Kenhttp://www.blogger.com/profile/02720825801825816765noreply@blogger.comtag:blogger.com,1999:blog-4933229084436849167.post-41818447702840676372010-08-30T03:22:24.620-07:002010-08-30T03:22:24.620-07:00Very nice, I am in the same boat with you. I under...Very nice, I am in the same boat with you. I understand many electronic basics, but am not comfortable enough to design a circuit like this, but I'm pretty sure I've got 1 or 2 of these kickin around. Will have to give this a shot<br />Thanks for the ideaStephenhttp://www.blogger.com/profile/18405356031315909322noreply@blogger.comtag:blogger.com,1999:blog-4933229084436849167.post-70855334039940089322010-08-30T01:50:04.875-07:002010-08-30T01:50:04.875-07:00Nice job!
However, efficiency should be calculated...Nice job!<br />However, efficiency should be calculated in watts not in volts. I don't think your first linear regulator had a efficiency of 28% approx, it's low. You should consider calculating it through this formula and tell us what the result is:<br /><br />Power IN = Power OUT + Losses in Regulator<br /><br />Power IN = Vbatt * Ibatt<br /><br />Power OUT = Vregulated * I<br /><br />Losses = (Vbatt - Vregulated) * I<br /><br />"I" equals the mA that your circuit is "sucking" from the regulator.<br /><br />So,<br /><br />Efficiency = Power out / Power in<br /><br />which means that the hotter your regulator gets the less efficient it is.Alejandrohttp://www.blogger.com/profile/02043153381714790010noreply@blogger.comtag:blogger.com,1999:blog-4933229084436849167.post-23457610407684596942010-08-29T19:44:58.210-07:002010-08-29T19:44:58.210-07:00@Jake
Fair enough, however I do say at the beginn...@Jake<br /><br />Fair enough, however I do say at the beginning "call it 12V". This is primarily because an 11.1V LiPo pack is well over 12V when fully charged and remains so for quite a long time. I think it's a valid generalization in lieu of an overly scientific (for me) graph of voltage and efficiency over time.<br /><br />And a big thanks and congratulations for being the first commentor on my website. Cheers!!Kenhttp://www.blogger.com/profile/02720825801825816765noreply@blogger.comtag:blogger.com,1999:blog-4933229084436849167.post-78887452729917663812010-08-29T15:20:20.493-07:002010-08-29T15:20:20.493-07:00Any linear regulator should have an efficiency of ...Any linear regulator should have an efficiency of the ratio between the desired voltage and the input voltage. For example, 3.3/12 = 0.275 or 27.5%. You are right on with 28%. But with your battery actually being 11.1v, the efficiency would be ~29.7%, of course varying with battery depletion.Jakehttp://www.blogger.com/profile/12108235977971397984noreply@blogger.com