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Powering an accessory through the Macintosh's USB port

  • Last Modified: January 08, 2007
  • Article: TA25890
  • Old Article: 58391
This article has been archived and is no longer updated by Apple.

Products Affected

iBook G4, Power Mac G5, iBook, MacBook Pro, Power Mac, Mac mini, iMac, eMac, PowerBook G4, PowerBook G3

The USB ports on Macintosh computers provide 5 V and 500 mA for each port, regardless of whether the port is USB 1.1 or USB 2.0. This is in compliance with USB specifications.

If you have an accessory (also known as a peripheral) which is acting oddly, such as not turning on or not being recognized by the computer, the device may require more than 500 mA of power.

If you have a USB device, or a chain of devices (such as a joystick plugged into a keyboard) that requires more than the available power, use a self-powered USB hub or see if the device comes with a power adapter.

See 43005: "USB Hub Description" for more information.

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