Re: PCMCIA/Cardbus USB and power

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?
___
"SMS ???. ?" <scharf.steven@xxxxxxxxxxx> wrote in message
news:4739d371$0$79897$742ec2ed@xxxxxxxxxxxxxxxxx
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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