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Low-power 2.5" hard drive

M

Mark R

Diamond Member
I'm looking for an HD that will work reliably in a bus-powered USB external enclosure. Most of the ready assembled drives need an external PSU, or tap into a PS/2 port, which really defeats much of the portability.

I know that there are some external drives that can be bus powered, but no one locally seems to have any. However, I was wondering if I could simply find a suitable laptop drive, and put it in an enclosure.

Any recommendations?
 
Yes, that is what I did. I bought a Toshiba 40GB 2.5" drive from Dell a few months ago and then picked up a slim 2.5" USB 2.0 enclosure at Meritline.com. Works great and not having an external PSU is really convenient.

Brad
 
All the 2.5" HDDs are 500mA, some even 550. The current limit for an individual USB port is 500mA. So including the USB-IDE bridge chip, you'll always be pushing your luck. Now since the overcurrent protection on mainboard USB ports tends to kick in quite early, having at least the ability to provide separate power to the drive assembly does make sense.
 
Thanks guys. I'm aware that the USB spec says 500 mA max (I'm designing a USB periph at the moment), and it was this that prompted my concern, because most drives have power requirements quoted at 1.0A @ 5V at least.

Anyway, to update - I just got a 40 GB HGST travelstar (80GN), and seems quite at home being bus-powered from both my PC and a powered hub. What's more remarkable is that the USB power gets pulled down quite heavily by the drive - add in the rather flimsy looking power-source select mosfet on the adapter board, and the drive sometimes pulls its supply down to below 4.3 V.

Unfortunately, the drive is going back, because it makes worrying clicking noises and has innumerable bad sectors (and in case you were wondering, it had these when it was first powered up, when I used a decent power supply).

I don't know what operating current the drive takes though - in device manager it says 98 mA, but I wonder if that is just displaying a rather over-optimistic device descriptor. I'm wondering whether I should try my luck with a faster drive (5.4k rpm if I can't get an exact replacement)....
 
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