Why Does SATA Hard Drives Use 3.3, 5, and 12V?

[bostonman]

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.

[bostonman]

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?

[wraper]

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.

[bostonman]

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.

[NiHaoMike]

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.

No SSD uses 12V AFAIK.

Some enterprise ones do.

[bostonman]

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.

[vk4ffab]

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.

It 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.

[Rafiki]

So would my SSD need 12v?

If 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.

[wraper]

Laptops don't even have 12V on SATA power connector.

[SeanB]

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.

[bostonman]

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.

The link is probably set wrong

What 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.