Are unpowered USB ports common on laptops?

  Al94 21:14 30 Mar 06
Locked

Haven't taken the plunge yet (actually glad as Dell have discontinued the Inspiron 6000 range in favour of the 6400 range with dual core processors. I notice the full spec states that there are 4 USB ports but they are unpowered. Is this common in laptops or a weakness in the spec? I'm thinking that some devices may not work without USB power.

  De Marcus™ 21:28 30 Mar 06

I've never personally come across a laptop that hasn't had powered USB ports, although obviously available as per your post, however, I'd consider it to be a fatal flaw in any case, I'd never get my pocket hard drive to run without a powered source, or for that matter any matter of gizmo's I pack in my bag when travelling.

  Al94 21:42 30 Mar 06

That's what I was thinking, here's the quote from the technical description
"4x USB 2.0 4-pin connectors (non-powered); 2 at rear, 2 on right-hand side of notebook system"

I have a scanner, webcam, pocket hard drive, sat nav and others that need a powered port. Can't believe this is right so going to contact Dell tomorrow.

  daba 00:46 31 Mar 06

A USB device will not work unless there is a power source to it. Most USB devices, eg Card readers, mice, Bluetooth adaptors etc., do not have alternative power sources, yet still manage to work OK in Dell laptops.

I think the term "un-powered" used by Dell could be misleading in this context, and could possibly mean "low-powered". I think what may be happening is that there is only one proper USB port on the motherboard, shared between 4 sockets, much like an un-powered USB hub. The maximum power available from the sum of the sockets in use will still be that of one USB port.

  bjh 09:09 31 Mar 06

Agree with daba.

Most portables have one USB hub sharing with as many outlets as they fit to the machine.

There will probably b 500mA shared.

This means no problems for USB pens and the like, which use 100mA. Fo USB broadband modems which use 400 - 500mA, you may need a powered hub if you need to use the USB pots for much else.

However, Dell machines are at least as well built as mot, and they will be no worse-powered in the USB departmet.

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