From: Victor Rehorst (victor_at_newtontalk.net)
Date: Wed Nov 05 2003 - 08:30:51 PST
Johannes Wolf wrote:
> In my opinion there is at least one point to think about:
>
> A standard PC keyboard needs to be powered. If you intend to power the
> keyboard from the Newt (which would be the most convenient thing to do),
> take into account that the keyboard will draw a not negligible amount of
> current from the Newt then. In case of the Keyboard I actually have this
> is 50mA @ 5V. If you consider that the Newt typically draws below 60mA w/o
> backlight this is double the current. So it would be recommended to power
> the Newt from the adapter while using such a keyboard.
From page 11 of the Interconnect Port specs:
http://dc.unna.org/unna/development/documentation/interconnect/newton_i.pdf
"The Newton Interconnect Port has a +5V power supply that can be used to
power external devices connected to the port."
...
"The total 5V power budget is 500mA, which must be shared by other devices in
the system (such as PC Cards), in addition to the Newton Interconnect Port.
Of this power budget, the Interconnect Port can draw a maximum of 100mA from
the 5V power supply."
As it sits here, my Newton consumes about 45mA, 72mA if I turn on the
backlight. So if they need 60mA just for the PC keyboard, plus a bit more
for the microcontroller, that should be fine.
-- Victor Rehorst - victor_at_newtontalk.net - chuma_at_chuma.org NewtonTalk list administrator - http://www.newtontalk.net Will the last person to leave the platform please turn off the backlight? -- This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries List FAQ/Etiquette/Terms: http://www.newtontalk.net/faq.html Official Newton FAQ: http://www.chuma.org/newton/faq/
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