Voltage drop - Page 1
Forum section: electronics / beginners

author: anoopsony
author_rank: Newbie
timestamp: June 03, 2015, 02:07:25 pm
content: I Need to build a small circuit, where i am supplying a constant 10V dc and should get an constant output of 7.4V dc.Can anybody help me on building this small circuit?Thankyou in advance.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 03, 2015, 02:11:19 pm
content: How much current, and put these in order of preference:1) Size/complexity2) Cost3) Efficiency4) Noise

author: anoopsony
author_rank: Newbie
timestamp: June 03, 2015, 02:13:02 pm
content: I have used a Voltage Regulator, is there any other Option where i dont want to use a voltage Regulator / an Op amp, because the circuit may work on hot/cold temperatures, in this coondition the op-amp cannot perform good.

author: anoopsony
author_rank: Newbie
timestamp: June 03, 2015, 02:14:22 pm
content: Current - upto 1.5AEfficiencyNoiseCostSizeQuote from: suicidaleggroll on June 03, 2015, 02:11:19 pm

author: w2aew
author_rank: Super Contributor
timestamp: June 03, 2015, 02:19:23 pm
content: There are several LDOs that would work fine, over temperature, etc. Fill in your criteria here, and it will spit out applicable parts:http://www.ti.com/lsds/ti/analog/powermanagement/power_portal.page

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 03, 2015, 02:19:54 pm
content: Then you definitely want a buck regulator, possibly even a buck followed by an LDO to clean up the output.I've used TI's Webench tool to design a buck converter before, it's pretty easy to use, or you could design your own by hand if you're feeling adventurous.

author: macboy
author_rank: Super Contributor
timestamp: June 04, 2015, 01:30:30 pm
content: Quote from: suicidaleggroll on June 03, 2015, 02:19:54 pmThat sounds like a lot of work for a one-off of a common device. Just go to ebay or your favorite far east merchant site and buy a "LM2596" buck converter module for <$1 shipped.You could buy bobbins and spools of nichrome and wind your own resistors too, but most people just buy them.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: June 04, 2015, 03:25:06 pm
content: Quote from: macboy on June 04, 2015, 01:30:30 pmYou're welcome to do that, but I refuse to support the grey market/counterfeit industry that is so rampant on those sites, and I won't recommend it to others either. Not only are those devices notoriously overrated and unreliable, continuing to support that industry hurts legitimate manufacturers. Besides, he put efficiency at the top of the list, and I doubt he'd do much better with one of those modules than he would with a simple linear regulator (74%).Have you ever used Webench? It's really not that much work, it does everything for you. Input your desired input voltage range, output voltage, and current capability, and it generates hundreds of designs that will meet it. You can sort those designs by BOM cost, size, efficiency, output ripple, etc. and then it gives you everything you need to know. Schematics, part numbers, BOM, graphs of everything you could want to know (efficiency vs output current and input voltage, thermal models, etc.), even the recommended schematic and board layout in a number of output formats (Altium, Eagle, etc.)http://webench.ti.comFor an input voltage range of 9-11, output of 7.4, and 2A capacity, there's a nice LM3150-based design that will be over 97% efficient at .6A and up for a 1k BOM cost of $3.24, 500 mm^2 footprint, and 12 mV P-P ripple.

author: Doc38343
author_rank: Contributor
timestamp: June 04, 2015, 04:51:26 pm
content: QuoteNICE!Thanks a mil for those handy links.... I love the hands on approach over the purchase, well that and i'm really impatient when i want to get-r-done..