Why Does SATA Hard Drives Use 3.3, 5, and 12V? - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 02:25:59 am
content: I'm curious why SATA hard drives use 3.3, 5, and 12v.The four-pin Molex for old 5.25" hard drives with motors provide 5 and 12v (maybe they have an internal regulator to make 3.3 and also use all three voltages). Then the newer SATA connectors added an orange wire for 3.3v which seems counterproductive since it added wires.Long story short, recently I upgraded an old oscilloscope from a 5400RPM to SSD; except I needed to convert ATA ribbon cable to SATA. Tonight I connected everything and discovered the ATA to SATA convertor has (what I assume) two regulators next to the input that are getting red hot.After reading Amazon reviews, it seems others have had similar issues with this board, but I began questioning why a SATA would take 5v and 12v along with (what I assume) a voltage regulator that possibly makes 3.3v.Seems a SATA hard drive would only need 5v for all the logic rather than 12v too; and possibly 3.3v.

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 02:35:24 am
content: That was the point I was making. 12v for the motor and 5v for the logic. That's the way I assume for old hard drives.Then the advancement of SATA and they add another voltage?As for for my last sentence, I made an error, I meant SSD. Why would an SSD also use 12v?

author: wraper
author_rank: Unknown
timestamp: July 16, 2024, 02:36:31 am
content: No SSD uses 12V AFAIK. 5V provides more power than 3.3V and more headroom for internal buck converters. And most if not all 2.5"HDD don't use 12V either.

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 02:50:14 am
content: I suspect the convertor I purchased is defective since the area with the two (possibly) regulators gets red hot.It doesn't cause the 12v or 5v on the Molex to sink, so this is a good thing.In any case, due to having to hardwire 5 and 12v from the scope power supply to a Molex, I began having to think about the actual voltages on hard drives, and wondered whether old ATA hard drives used 3.3v too, and why a SATA would need all three.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 16, 2024, 03:08:45 am
content: The 3.3V was for newer logic at the time, a few early drives used it but then the chips went to even lower voltages making that rail not very useful. Now they repurposed the 3.3V line as a hardware power down with 3.3V telling the drive to power down, the SATA standards organization must have been drunk or something to make such a big compatibility error.Quote from: wraper on July 16, 2024, 02:36:31 amSome enterprise ones do.

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 03:15:09 am
content: So would my SSD need 12v?I'm trying to figure out why 5 and 12 go into the board when it's an SSD without a motor. For a visual, I've attached a picture the adapter I'm talking about.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: July 16, 2024, 04:32:22 am
content: Quote from: bostonman on July 16, 2024, 03:15:09 amIt does not need 12v, it should only require 5V and nothing more. Just because there are other voltages on the connector does not mean they are used.

author: Rafiki
author_rank: Contributor
timestamp: July 16, 2024, 11:31:03 am
content: Quote from: bostonman on July 16, 2024, 03:15:09 amIf you wanna have a definite answer to your question then look at YOUR yet unknown SSD. It's usually printed on it or at least is noted in it's specification. Showing a picture of something else than your SSD will lead to guessing only.

author: wraper
author_rank: Unknown
timestamp: July 16, 2024, 11:51:50 am
content: Laptops don't even have 12V on SATA power connector.

author: SeanB
author_rank: Super Contributor
timestamp: July 16, 2024, 12:12:04 pm
content: Yes almost all SSD drives will tell you power requirements, though the currents are generally given as peak current, the operating current is normally lower than that, but it is for sizing of power demand. Almost all just are fine with 5V only, simply not connecting the 3V3 and 12V pins, or having a pull up on the 3V3 instead to provide voltage there if the drive uses the 3V3 as power on rail. internal to the SSD the 5V will be converted to an IO voltage of 3V or so, and a core voltage that depends on chipset, generally something from 0V9 to 2V0 to run the logic, and a separate supply on each flash die that generates the needed erase and write voltages, runnning off the internally made 3V3 or 5V supply. Most only need 5V, and often laptop spinning drives also only use 5V as well, not needing anything other than this single rail.Note the adaptor you show only seems to use the 5V from the Molex socket, being designed as interface from older IDE to newer SATA, so it has to use the molex to get 5V supply. The link is probably set wrong, try with it not connected to any pin, which will probably let it work, the 2 regulators getting hot is likely the power demand for the on board ASIC, needing likely a 3V3 rail, and the power being too much for a single linear regulator, so there are 2 in parallel fed off the 5V rail.

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 03:13:46 pm
content: Later I'll take a closer look at the label to see if it lists voltages or power requirements.Looking online at SATA connector pinouts, they list all three voltages and where my confusion came from.QuoteWhat do you mean by 'link'?My guess was that the 12v wasn't needed, but, when I saw the SATA pinout with all three voltages, I figured I'll connect the 12v too since routing wires and making the connections to the power supply is difficult.

author: mariush
author_rank: Super Contributor
timestamp: July 16, 2024, 03:35:28 pm
content: Quote from: wraper on July 16, 2024, 02:36:31 amSome old Intel enterprise SATA SSDs used 12v , here's an example :https://www.ebay.com/itm/386937174169Some newer Intel Enterprise SSDs use 12v .. ex this U2 P4510 :https://www.ebay.com/itm/156169624411Kinda makes sense in servers, where you may have 12v only power supplies.But yeah, very few SATA SSDs use anything but 5vTo the best of my knowledge 3.3v was added with the idea that it would be used in laptops and tablets .... but drive manufacturers didn't bother relying on 3.3v because of all the molex to sata adapters out there that don't include the wire.Later they messed up the standard even more by making the 3rd 3.3v contact in the sata power connector for sleep mode on drives (prevent spinup) and in the latest standards 3.3v is actually deprecated (they encourage it to be removed from sata connectors)

author: wraper
author_rank: Unknown
timestamp: July 16, 2024, 03:52:31 pm
content: Quote from: mariush on July 16, 2024, 03:35:28 pmThese series were released in 2018 or earlier. It pulls so much power, power connector would be barely above max current rating if 5V was used instead. Probably there are even more power hungry models in that model range.

author: bostonman
author_rank: Super Contributor
timestamp: July 16, 2024, 04:01:16 pm
content: QuoteThis makes more sense.So most likely all this ATA to SATA needs is 5v and I can save space/wire by removing the 12v.Unfortunately I still have the issue of it not working. Maybe for curiosity, I'll check to see if the 12v goes anywhere. Maybe they did something crazy and using the 12v for the onboard IC and the 5v goes directly to the SSD.

author: bostonman
author_rank: Super Contributor
timestamp: July 17, 2024, 02:37:57 am
content: Quick measurements reveals the 5v and 12v from the Molex go directly to the SSD SATA connector hard drive pins. Also, the 5v goes into both regulators.From what I can tell, they are LM1117. They have '1117' (I assume the part number) and one has A338. the other has A347 (I assume these are date codes).A replacement should be arriving tomorrow, so I'll test it. If this one doesn't work, then I'll take a few voltage measurements.

author: antercreeper
author_rank: Contributor
timestamp: July 17, 2024, 03:20:37 am
content: 12V could be used on enterprise 2.5inch SSD, but should be optional only, meaning that only 5V should be enough. However it is better if you can provide 12V.

author: bostonman
author_rank: Super Contributor
timestamp: July 18, 2024, 02:17:46 am
content: Today I received the replacement ATA to SATA. Prior to connecting it to the SSD, I left it powered and the regulators remained cool.After connecting the board, BIOS recognized the hard drive and the system booted fine.I measured both regulators on the good board; one is 1.8v and the other is 3.3v. The bad convertor has 1.8v, but the 3.3v regulator is about 0.4v or 0.7v (and the regulator was hot to touch within less than thirty-seconds).I removed the 12v pin and the SSD worked fine, so everyone is correct, 12v is not needed. Not sure if 3.3v from the regulator is for the IC (maybe it takes both 1.8v and 3.3v) or if it's for the SSD in order for it to work.