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Re: [ts-7000] Re: Setting USB Power

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Subject: Re: [ts-7000] Re: Setting USB Power
From: Jim Jackson <>
Date: Sat, 20 Jan 2007 22:34:44 +0000 (GMT)


On Fri, 19 Jan 2007, tyerslockandblock wrote:

> Hi Markus
>
> You are absolutely right, my drive is 2.5" and NOT 3.5" as I wrote; I
> really should re-read my postings carefully before hitting the send
> button :-(
>
> Anyway, being a 2.5" drive, it does in fact require a 5V DC supply -
> which can be USB-supplied.

Yes but you have not mentioned at any point what power supply you are
using to supply the 5V for the TS board. If that is insufficient to
provide the initial surge (which can be quite a bit more than the
power drawn after start up) there will be problems.

> I take on board your comments about higher initial power consumption,
> but this drive has been used succesfully for over a year while
> attached to a hacked and frequently re-booted Linksys NSLU-2 (which I
> used as my original prototype platform), so I am somewhat surprised
> that it would hiccup on my TS-7260.
>
> Your suggestion that I should perhaps invest in a powered USB hub is a
> good one - and may well be the route I need to follow - but perhaps
> someone out there has an alternate suggestion which won't cost me
> money ;-)
>
> Cheers,
> Philip
>
>
>
> --- In  Markus Peuhkuri <> wrote:
> >
> > tyerslockandblock wrote:
> > > I have a USB-powered 3.5" disk drive which I wish to use during
> > > application development. This device requires a 5V power supply, which
> >
> > Are you sure that it is 3.5" and needs only 5V?  AFAIK, all 3.5" drives
> > need both 5V and 12V and draw more current than USB can supply.  Even if
> > your drive would have 100% efficient 5V to 12 V converter, your USB port
> > should supply on average about 2 A of current (10W) (USB max is 0,5 A)
> > and at startup a drive can take three or four times of that.
> >
> > However, an 2.5" drive is just in USB specs on average (like 2.2 W) and
> > needs only 5V, but you may have problems at startup, as even a slow
> > drive can take more than 1.1 A at start.
> >
> > For example, I have problems with my laptop (Dell D600) and 2.5" USB
> > drive.  I need to use USB hub with external power or then PC Card with
> > USB connectors to supply enough current to get it running.  There is a
> > windows patch by Dell to fix it, it just causes windows to ignore
> > overcurrent condition -- could patch Linux to do the same, but I'll
> > prefer data integrity :-).
> >
> > Try with USB hub with power input.
> >
> > t. Markus
> >
>
>


 
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