Cut-Off voltage oft the Beaglebone

GoogleGroups
1

Hi,

the reference manual states, that the powermanagment circuit of the
Beaglebone will prevent the boot of the board, if the voltage raise
above 5V.

The reason, why I ask has the following background: I want to feed
my Beaglebone with a LiPo Powerbank, which may have slightly more
than 5V, if idle.

When connected to the board, the board will not drain much Amps,
since the powermanagement is the only which "tastes" the voltage.

This result in a slightly overvoltage condition and the board will
not start. If the board would start, the voltage would fall to the
nominal value of 5V...but...

Are there informations from own experiences, what the exact voltage
is the one, which really is evaluated as "overvoltage" by the power
management ... is it 5.00000V or is (for example) tolerated to feed
5.2V into the board?

Thank you very much in advance for any help!

Best regards,
mcc

2

5.2 will work fine as stated in Table 2.

Gerald

3

Hi Gerald,

...damn...I overlooked exactly this information in the manual
...thank you for pointing me to that table!

5.2V was (due to my not-knowledge) only an example...

Suppose the Powerbank would have 5.5V when fully charged...the board
would not start then.

How can I "kill" 0.3 V in a energy saveing way? How can I prevent,
that this amount of voltage is always subtracted, even when the
Powerbank is slightly discharge and will feed a voltage below 5.2V
into the board?

Best regards,
mcc

Gerald Coley <gerald@beagleboard.org> [12-08-27 18:40]:

4

The trip point varies by the device and system configuration. I would give it a try and see exactly where the NCP349 shuts down. The issue here is USB, I don’t know whtat you need to send much over 5.5V to the USB port. You won’t cause any damage to the board at 5.5V but the USB devcies may not like it.

Gerald’

5

mcc-

How can I "kill" 0.3 V in a energy saveing way? How can I prevent,
that this amount of voltage is always subtracted, even when the
Powerbank is slightly discharge and will feed a voltage below 5.2V
into the board?

Whats about DC-DC Power Supplies? e.g. the
XP POWER - JCA0405S05 - DC/DC converter, 4W, 5V
Input is 4.5-9.0 VDC

There are a lot of similar devices on the market, maybe you find
something a bit less expensive. But usually these devices are really
low drop.

HTH
didi