I would like to use the USB as host and I want to have a battery-only
If I put in parrallel two energizers
(http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=N321-ND), would I kill the board with 6V? I tried one energizer and it's not enough on the DC connector, the first led goes on but that's all (board works with 5V power supply so the board is OK),
6V will kill the board. Maybe not right away, but shortly there after. Please read the System Reference Manual for more information.
One more thing. You can use a cell phone charger, such as the one energizer has that has 2 AA batteries that puts out 5V. This can go to the USB port to power the board. You could also modify one of those with a DC connector and power it from there to the board
Gerald Coley wrote:
6V will kill the board. Maybe not right away, but shortly there after.
Please read the System Reference Manual for more information.
I haven't RTFM in a while, but your response suggests that if one is going to
power the board with a wall-wart power supply, it has to be a _regulated_ supply.
An ordinary, just-picked-it-up-at-Radio-Shack or salvaged-it-from-a-toy type
will not be good, because those supplies are rated at load, and have terrible
specs in other conditions. In particular, one labeled "5V" might actually be 8V
until fully loaded. And since Beagleboard draws so little power, one of those
"5V" supplies will probably destroy the board.
Do you concur?
That is an interesting question you pose, and I do not know.
Looking at the schematic, the DC power in is regulated using a TPS73701 which has a max input voltage of 5.5V
See http://focus.ti.com/docs/prod/folders/print/tps73701.html for details.
A TPS2061 is also used else where on the board which also has a max input voltage of 5.5V
So I would not recommend running the Beagle at 6V or from an unregulated power supply.
But I do not see a reason that the Beagle could not be run at 4.5V as the TPS73701 is a LDO regulator outputting 4.2V. TPS73701 only needs 130mV of headroom allowing the input voltage to fall to 4.33 V. I have not looked at the whole circuit in detail, so this idea may not work.
Although if you did want to run the Beagle Board off batteries. Building a small up or down converter to generate a regulated supply would not be too hard.
Don’t cheat – Compete
Don’t expect – Suggest
I agree. That is why the spec says 5.2V and that means all the time, not just after it warms up. Great points!
Gerald Coley wrote:
I agree. That is why the spec says 5.2V and that means all the time, not
just after it warms up. Great points!
Heh, "warms up". That's what you have to do to get those el-cheapo power
supplies into spec: "warm up" the beagleboard with them! But then, oops!
I've got a 'cheapo' 4.5 v power supply and the board has booted every time
and has been up for weeks on it.