There is no Vcc pin on a Series III connector. You may be thinking of the
DSR line which is tied to Vcc via a resistor. If you applied 3.3v to this
pin, the current would be severely limited heading upstream into your Palm.
(Not to mention what kind of damage you could do to the Palm's voltage
regulator if its not already properly protected.)
-----Original Message-----
From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
To: Palm Developer Forum <[EMAIL PROTECTED]>
Date: Thursday, May 11, 2000 12:04 PM
Subject: RE: Powering a device from the Palm III
>Ok. Here's another random thought.
>
>What if I use, say, a Linear LT1300 Step-up 3.3V DC/DC converter (almost
>exactly the same one the palm uses to regulate the 2 AAA cells to make its
>3.3 V supply, I think) and connect it to the VCC pin in the hotsync port?
>Might this work?
>
>i.e. keeps 3.3 V output for me to use even if I start drawing current from
>the pin and input to the regulator sags a bit. The LT1300 produces 3.3 V
>output even with as low as 1.8 V input , corresponding to 5 mA drawn from
>VCC. Take into account efficiency (80% or so, says the data sheet) and I'd
>still be safe.
>
>Only problem I can perhaps envision is the regulator not being speedy
>enough to handle an input sag when parts of my circuit jump into activity
>at various times. Anyone used an LT1300 or equivalent?
>
>I probably missed something colossally obvious again...
>
>Kris
>
>At 11:15 AM 5/11/00, you wrote:
>>Another possibility would be a rechargeable coin cell. I haven't dealt
with
>>them in quite a while, but from what I recall you could get a 3.3 V Li-ion
>>cell about the size of a fat quarter that you could trickle charge. As
long
>>as you are adding more energy than you are using this scheme will work.
>>
>>Good luck and let us know what your final solution is.
>
>
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