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Posted by none on November 13, 2007, 10:06 pm
Please log in for more thread options SMS, interesting comments, especially about the Dc-Dc upconverter. I
wonder if ALL adapters can furnish this 500ma power we've talked about
or just those that advertise. Any idea?
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> none wrote:
>
>> Question is, is there a particular brand of PCMCIA USB adapter which
>> can
>> provide the 500ma per port which is needed for powering the HDD?
>> Would
>> prefer to NOT need external power.
>
> Yes, and this was discussed extensively in a previous thread. Can you
> actually believe the manufacturer's specs is the real question!
>
> "http://www.trendnet.com/products/TU2-H2PC.htm"
>
> "ftp://ftp10.dlink.com/pdfs/products/DUB-C2/DUB-C2_ds.pdf" Amazon and
> NewEgg both have it.
>
> Also understand that the computers USB ports are usually capable
> providing well over 500mA, so just because the HDD works on a USB port
> on the laptop, doesn't mean that it will work on a USB port from a
> Cardbus slot that provides 500mA, though most external notebook drives
> do draw less than 500mA.
>
> Can my ThinkPad T41 provide the 500ma needed from the internal
> PCMCIA/Cardbus connector?
>
> That's the real question. Actually it's much more than 500mA. The card
> is rated to supply two ports at 500mA/5V, while the Thinkpad is
> supplying 3.3 volts in CardBus mode. So the CardBus card has a DC-DC
> converter to up-convert the 3.3V to 5V. So the slot must provide 5/3.3
> *1000mA, plus whatever extra for the losses in the DC-DC converter
> (typically 80-90% efficiency). However if you're only using one of the
> two ports on the CardBus card, it'll probably work just fine.
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