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Mar. 14th, 2010 10:24 pmPlugging in an external USB hard disk apparently made my USB 3G modem disappear for a few moments. Weird.
The hard disk did seem to struggle to spin up - I'm guessing the combination of the spinup current and the draw of the 3G dongle was more than what the laptop was happy to deliver.
Now, in theory, USB devices are supposed to ask the controller how much power is available and draw no more than that, with an upper limit of 500mA. In practice, the rated spinup current on most hard disks (including this one) is much more than that. Isn't it wonderful the way standards get ignored?
The hard disk did seem to struggle to spin up - I'm guessing the combination of the spinup current and the draw of the 3G dongle was more than what the laptop was happy to deliver.
Now, in theory, USB devices are supposed to ask the controller how much power is available and draw no more than that, with an upper limit of 500mA. In practice, the rated spinup current on most hard disks (including this one) is much more than that. Isn't it wonderful the way standards get ignored?
