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HiVolt
Premium Member
join:2000-12-28
Toronto, ON

HiVolt

Premium Member

3.5" USB 3.0 bus powered enclosure

Like the topic states, has anyone seen a 3.5" USB 3.0 bus powered enclosure?

I understand that power has been increased in USB 3.0 spec, but no idea if its enough for even a "Green" 3.5" drive.

FizzyMyNizzy
join:2004-05-29
New York, NY

FizzyMyNizzy

Member

I only see it for 2.5
decx
Premium Member
join:2002-06-07
Vancouver, BC

decx to HiVolt

Premium Member

to HiVolt
Most green 3.5 inch drives require over 1A of current to operate (WD quotes 1.1A for most Caviar Greens for example). While USB 3.0 does significantly improve upon the 500mA limit for USB 2.0, it still specifies only 900mA of current per port. This will allow most 7200rpm 2.5 inch drives to operate without a secondary cable or an external power supply, but still isn't enough for low power mechanical 3.5 inch drives.

HiVolt
Premium Member
join:2000-12-28
Toronto, ON

HiVolt

Premium Member

Ah, I thought it was more than 900mA for USB 3.0...

Speaking of 2.5" 7200rpm drives, I have a Seagate 500GB 7200rpm in a USB 2.0 enclosure that I've had no issues using bus powered in a variety of machines...

Though maybe those larger 12.5mm 1TB drives would need more.
decx
Premium Member
join:2002-06-07
Vancouver, BC

decx

Premium Member

I had several older 7200rpm Seagate drives that would sometimes just tick if I plug it into a USB 2.0 drive but would work just fine on a 3.0 port or with a supplemental power supply. More recent drives may definitely be more efficient.

aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor to HiVolt

Member

to HiVolt
I think most 3.5" drives also need +12V, and that's not available via USB. For relatively low power (i.e. serial port) it's easy to generate +12V from +5V, but when you need to spin up a 3.5" HD, that's a lot more than low power.