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Please help regarding usb2.0 case for 2.5inch external HDD

Discussion in 'Laptops' started by Faisal Khan, Aug 21, 2003.

  1. Faisal Khan

    Faisal Khan Guest

    Hi

    I have Sarotech usb2.0 2.5inch (9.5mm) HDD case. It works just fine
    when connected to Pentium II 266 Mhz DeskTop WITHOUT THE NEED OF
    EXTERNAL POWER SUPPLY. But when i connect it to my Toshiba satellite
    pro series 4300 (650 Mhz)it does not work at all and it seems that the
    laptop's usb port is not supplying enough power to the mentioned
    device. But when i use a separate power adapter (5V 1000mA) it works
    fine on laptop too!

    Is there any difference between the usb ports of a desktop and a
    laptop regarding the amount of power it supplies??????

    PLEASE NOTE: both desktop and laptop have windows 98 SE
    both machines have usb 1.1 while the sarotech case is
    usb2.0

    Thanks in advance
     
    Faisal Khan, Aug 21, 2003
    #1
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  2. Faisal Khan

    Ian Stirling Guest

    Generally, yes.
    The motherboard typically has 20-30 amps or more of power at 5V easily
    available.
    The USB ports are typically current limited only loosely, to avoid actual
    fires, and though the nominal current limit of the USB port is 500ma,
    it may only turn off at over an amp.

    In laptops, things are different.
    Every extra watt that the power supply has to produce, it needs to be
    a few grams heavier, the batteryh needs to handle higher peak loads, the
    cooling system has to remove the extra heat, ...

    This means that there is a good reason to actually limit the current to
    the specs, rather than taking the somewhat looser attitude that
    motherboard ports take.

    --
    http://inquisitor.i.am/ | mailto: | Ian Stirling.
    ---------------------------+-------------------------+--------------------------
    Lord, grant me the serenity to accept that I cannot change, the
    courage to change what I can, and the wisdom to hide the bodies
    of those I had to kill because they pissed me off. - Random
     
    Ian Stirling, Aug 21, 2003
    #2
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