From: Frank Gruendel (fg2_at_pda-soft.de)
Date: Sat Jan 10 2004 - 16:45:30 PST
Hi all,
it appears that my trust in the competence of the Newton
hardware developers has become a little dented a minute
ago. I always thought there's enough monitoring going on
to prevent any "unpredictable behavior" in the power
circuitry. Recently I had a 2100 on my workbench that
might or might not have been a victim of such a
behavior. Whatever the cause, it killed a transistor and
a fuse and made a capacitor explode.
This is what I found in a newsgroup, posted (a long time
ago) by a former member of the Newton team (at least
the email address makes one think that).
Quote
Von:Jason Rukman (rukman_at_newton.apple.com)
Betrifft:Re: PCMCIA API
The MP2K allows use of somewhere around 800mA when using the
rechargeable
batteries and about 500mA when using Alkaline batteries. It can also
provide 800mA when the AC adapter is connected. These numbers apply to
BOTH slots, and the serial port combined. One slot can consume all the
power. If the use of other devices at the same time is attempted, the
supply will go out of regulation. This can cause unpredictable
behaviour.
Unquote
Since the interconnect port is specified at 100 mA maximum current
and the Newton itself eats about 80 mA with the backlight on when doing
nothing (more when doing things like HWR), this leaves about 100 mA
that you can safely draw from both slots together if the Newton is
running off alkalines or 400 mA if it is running off the rechargeable
pack or the AC adapter.
Might be a good idea to put this into the FAQ. I'd be interested to
hear from people whose Newton died while they had one or two
power-hungry
cards in them.
Frank
-- Newton Software and Hardware at http://www.pda-soft.de
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