1.1V Voltage Regulator Request - Page 1
Forum section: electronics / general

author: diyaudio
author_rank: Frequent Contributor
timestamp: June 27, 2015, 10:36:55 pm
content: Can anyone recommend a good 1.1V @ 1.5A LDO to power a processor core, I cannot seem to find many LDO solutions, Google search results are 90% buck based controllers and my aim is to keep the BOM and complexity down.So far I only found this, and its in those pesky QFN (not a big issue, just a dog to hand solder)http://www.ti.com/lit/ds/symlink/tps74801.pdfCan anyone recommend alternatives ?

author: Psi
author_rank: Super Contributor
timestamp: June 27, 2015, 10:54:42 pm
content: At 1.1V and 1.5A your going to drop voltage pretty fast just getting the power into the ICMaybe a 1.2V reg would be better? Whats the max input voltage of your processor?Quick digikey search found a 1.2V 1.5A Vreg pretty easy. Min input is 2.2Vhttp://www.digikey.com/product-detail/en/AP7363-12D-13/AP7363-12D-13CT-ND/3829380

author: Andreas
author_rank: Super Contributor
timestamp: June 28, 2015, 05:07:58 am
content: What about something like LT3081 or LT3083 in TO220?With best regardsAndreas

author: diyaudio
author_rank: Frequent Contributor
timestamp: June 28, 2015, 06:47:37 am
content: Quote from: Psi on June 27, 2015, 10:54:42 pmMaximum input is 5V. The normal processor core supply voltage is 1.1V, max is 1.15V.

author: amyk
author_rank: Super Contributor
timestamp: June 28, 2015, 12:53:06 pm
content: There's a reason why you only find switching regulators at that power level.You will need to dissipate nearly 6W of heat, to run a device that will use 1.65W at most. That is a horrible waste of power.The AP7363 mentioned above has a best-case thermal resistance of 52.8C/W junction to ambient, meaning that it would go over 300C above ambient if it were made to dissipate 6W. The TPS74801 is not much better, at 35.6C/W.

author: Scrts
author_rank: Frequent Contributor
timestamp: June 28, 2015, 01:47:26 pm
content: LDO for a processor core? I bet it doesn't drive any high precision analog blocks, so forget using LDOs. DC/DC converters are used for that purposeCheck TI or Linear DC/DCs, proven to be good

author: poorchava
author_rank: Super Contributor
timestamp: June 28, 2015, 02:14:44 pm
content: I like ST1S10 for applications like that. Small inductor and easy application schematic. And it's cheap. Low voltage buck regulators are nowadays really easy to implement.Sent from my HTC One M8s using Tapatalk

author: hans
author_rank: Super Contributor
timestamp: June 28, 2015, 03:19:49 pm
content: Even the 20-pin TPS74801 QFN variant will probably overheat with the load proposed.E.g.Vin=5V, Vout=1.1V, Iout=1A (assuming "average") -> (5-1.1)*1 = 3.9W3.9W * 35.6C/W + 30C ambient = 168CAbsolute max is 150C, probably want to keep it under 100C if you want to operate for a long period of time.It would probably work if you could get a TO220 LDO regulator like a LT3080 and put it on a small heatsink.In that case I think aLDObuck is much simpler and cheaper. Just find one that can down to 0.8V (edit: as often others get stuck at 1.2V or so) and re-cycle the 1.2V application schematic

author: diyaudio
author_rank: Frequent Contributor
timestamp: June 28, 2015, 03:54:19 pm
content: Quote from: hans on June 28, 2015, 03:19:49 pmYou guys are 100% percent correct, my calculations were based on dynamic power, however I never considered what happens if I ran the core continuously with some lengthy floating point computationsI I will settle for a buck then, that ST1S10 looks nice and simple (thanks!), however now im spoiled for choicemaybe a dual (with integrated FETS) 1.1v @2A, and 3.3V @ 1A will be better, I can then eliminate my 3.3V LDO and slip one solution..

author: poorchava
author_rank: Super Contributor
timestamp: June 28, 2015, 04:10:06 pm
content: IMO considering LDO that will dissipate anything more than 0.5W or so is pointless unless it's a lab power supply or you are powering very sensitive analog stuff.Sent from my HTC One M8s using Tapatalk

author: LDM
author_rank: Contributor
timestamp: June 30, 2015, 02:30:40 pm
content: Is the 1v1 for a Sharc? If so, I would highly recommend the regulator circuit from the dev board. We've done many Sharc designs, and always come back to the ref design, having lost many other attempted cheaper/smaller circuits to the magic smoke.

author: diyaudio
author_rank: Frequent Contributor
timestamp: June 30, 2015, 11:33:48 pm
content: Quote from: LDM on June 30, 2015, 02:30:40 pmYep, SHARC 21489 there are a few options, magic smoke?, its rather expensive smoke

author: LDM
author_rank: Contributor
timestamp: July 01, 2015, 09:28:17 pm
content: This is the default circuit I've been using to power two 21489 devices in various products for over 3 years with zero failures. It's probably more involved than you want, but is guaranteed to work.

author: mariush
author_rank: Super Contributor
timestamp: July 01, 2015, 11:05:10 pm
content: If you really want linear, a good IC would beLT3081but of course, it's expensive ( ~ 6$ for one). LT3083 would be good for 3A but it's close to 10$.

author: Scrts
author_rank: Frequent Contributor
timestamp: July 02, 2015, 08:09:15 am
content: Quote from: mariush on July 01, 2015, 11:05:10 pmLinear is always the most expensive option. I've successfully usedMPS. Now I mainly rely on TI products. The designs are automotive, so passes all the tests and must last 15 years.

author: diyaudio
author_rank: Frequent Contributor
timestamp: July 02, 2015, 04:32:01 pm
content: Quote from: LDM on July 01, 2015, 09:28:17 pmThanks!