Hi,
It seems the specification allows USB devices to draw up to 100mA (for a "low power" port) and 500mA (high power port).
Does anyone have any idea of the incidence of high power ports? Especially on laptops.
For a design with USB control, I am trying to decide if it is worth including an option to take all the power from USB, rather than a wall-wart type adapter. It would be great just to have the one plug, and also allow fully mobile operation. But if a large fraction of laptops only have low power ports, it may be more trouble than it is worth. (It occurs to me that in order to support plugging in an external hub, all laptop ports *ought* to be high power).
Thanks,