Re: power over usb in the new garmins?

From: Meindert Sprang (mhsprang_at_NOcustomSPAMware.nl)
Date: 01/28/05 

Date: Fri, 28 Jan 2005 16:17:57 +0100

"Jack Erbes" <jackerbes@adelphia.net> wrote in message
news:7p6dnUCE_vJLzGfcRVn-gQ@adelphia.com...
> Meindert Sprang wrote:
>
> > "Jack Erbes" <jackerbes@adelphia.net> wrote in message
> >>The voltage supplied by a USB port is 5 volts. And the USB port is
> >>rated for a maximum draw of 500 milliamp or 1/2 Amp. So both of those
> >>are considerations using the USB port for power. The handheld GPS that
> >>use two AA cells for power are 3.3 volt (nominally) devices and hitting
> >>them with 5 volts could be damaging.
> >
> >
> > Yep. And all GPS manufacturers using the lates state of the art DSP
> > technology probable have never heard of voltage regulators... :-))
>
> So should that be taken as your recommendation to go ahead, plug it in,
> and see if they used a voltage regulator?

No. I responded only to your comment, but missed the previous post. So I
probably pulled it out of the context. Sorry for that.

> My assumption is, if the input voltage is not listed as fairly wide
> voltage range, the input voltage is probably not regulated.

It is indeed not wise to just take the 5V from the USB port and stuff it
into the 3V battery terminals. But if the GPS has an external power
connection, it will most likely accept anything between 5 and 30V since many
are meant to be operated from a 12 battery on a boat, for instance. And
there you can apply 5V from the USB port as well without damage.
Meindert