On January 22, 2007 06:24 am, tyerslockandblock wrote:
> Hi Jim
>
> I am powering my TS-7260 using an unregulated 12V 2A power supply as
> found in a burglar alarm enclosure (BTW, because these things are
> manufactured in huge volumes, this a very inexpensive way
> to box a project - solid gauge metalwork and an enclosed power supply
> for very few $).
Can you give us a link to where we can buy one of these cheap unregulated
supplies?
-Curtis.
>
> Being an unregulated supply, I am therefore relying on the on-board
> requlator to perform the necessary magic.
>
> Of course, this is where the problem might lie, as the 12V is regulated
> down to 3.3V, whence charge pump circuitry is used to create the 5V
> rail. It is quite likely that this latter circuitry hasn't got the
> necessary "oomph" to handle the initial current spike which the USB
> hard drive requires.
>
> It's a shame that the board didn't do serial regulation instead (input
> regulated down to 5V regulated down to 3.3V) as this would likely have
> overcome the problem.
>
> Anyhoo, since my drive can be powered externally, I will follow
> Markus's suggestion and buy a cheap 5V power supply.
>
> However, this leaves me with a new problem :-(
>
> By default, the USB ports are enabled to receive the internally
> generated 5V supply - which I neither need nor indeed want. This can
> of course, be turned off by setting the appropriate bit in register
> 0x1200_0000 using the poke8 command. The only problem is that this
> will be done late in the boot cycle, whereas I need it to be in effect at
> power up - otherwise the power supply electronics will get their
> knickers in a twist!
>
> So, my problem has now morphed to this: How can the "USB 5V Power" bit
> in register 0x1200_0000 be made to default to "off" at power up,
> rather than "on"
> as at present?
>
> All suggestions (as usual) gratefully received.
>
> Cheers,
> Philip
>
>
>
>
> --- In Jim Jackson <> wrote:
> >
> >
> >
> >
> > 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 <puhuri@> 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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