One of the worst things about
upgrading your cell phone is
that you lose all your accessories, such as the car charger/
adapter for the phone. Such
was the case recently
when I upgraded to a
Motorola Q and my wife to a Motorola KRAZR. But to
my surprise, the power connector for both was the
familiar USB mini connector.
This is not to say that I had a USB car charger on
hand—I do have to purchase one. But they're easy
enough to find, and inexpensive, too, selling for about
$10. What's more, if I buy two—one for each car—I no
longer have to worry that the right adapter is in the
right car. I don't know if all cell phone makers are
employing the mini USB port for power, but it would be
great if they did.
Naturally, there's more to the story. I looked at the
back of the AC adapter that came with the phones and
noticed that the output is 5.0 Vdc at 850 mA. This got
me thinking about the SIMPLE SWITCHER evaluation board that I got from National Semiconductor and
wrote about in the February issue. The output for that
board is 5.0 Vdc at 3A. And it's just sitting on my workbench with nothing to do. Also sitting around in various
places are USB and cigarette lighter connectors/cords.
Here's what I'm thinking: Wouldn't it be great to
have one device that handles car, AC and battery
charging for the cell phones. I could take any of the old
AC adapters I have lying around, connect it to the
board and get 5V out. Also, if I took four AA rechargeable batteries, I could connect them to the board and
get a regulated 5V out. Finally, I could connect a cigarette lighter connector/cord to the board as well.
All that's missing, I think, is the pinout for the USB
mini-connector, so that I know how to connect the USB
cord to the 5V output. I found this information easy
enough on the web in the USB Wikipedia at http://en.wikipedia.org/wiki/USB. So that's it, I think.
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