Question on USB root hub

[Daniel]

Hi everybody,

not a problem but a question:

If I open device manager > USB Bus Controlers >>> select one particular USB
Root Hub entry, >>> Properties > On/off tag, then I can see a list of the
devices connected to this Hub.

My question is: does the "Required Power" indication (for example 500 ma)
correspond to the actual current consumption of the corresponding device,
or, indeed, does it indicate the current the port should be able to deliver.

I am asking this, because the 2 devices which bear the indication 450 mA
and 500 mA (which is equal or close to, if I am not mistaken, the max power
a USB port should be able to provide) are respectively my smartphone and a
Webcam.

(sorry about my English and the lousy translation from French).

Anyone?

Many thanks in adance for your kind advice.

with brgds,
Daniel

 

[Dusko Savatovic]

Daniel,
I wouldn't wory too much.
All USB devices which are supposed to run from the USB power are designed so
that they can work that way. That's why we have standards. If the device is
not supposed to be powered from the USB, than you will get an AC adapter
with the device.
If the device that is supposed to work from the USB power, does not work,
return it to the manufacturer.
I also have a webcam and a mobile phone (not a smartphone) and some other
devices (2.5" USB2 drive for example) and they all work as advertised (from
the USB power)

 

[Daniel]

Many thanks, Dusko, for your time and kind message.
I understand what you say. I was concerned that such "small" devices seem to
consume so much power from the USB Ports, close to the specs limit.
(webcam, smartphone).

Best,
Daniel