How much power can be drawn from USB.
Is a Samsung Super-Writemaster Slim extern DVD drive that draws power from USB ok?
USB Power
Re: USB Power
Check out the Wikipedia article on USB and Power: http://en.wikipedia.org/wiki/USB#Power
From what I can tell (by glancing around the web), the maximum current USB2 can supply is 500mA -- multiply that by 5v and you get 2.5 watts. Not exactly a lot of power.
What's the power draw of your drive?
From what I can tell (by glancing around the web), the maximum current USB2 can supply is 500mA -- multiply that by 5v and you get 2.5 watts. Not exactly a lot of power.
What's the power draw of your drive?
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fluffycloud
- Posts: 55
- Joined: Tue Mar 24, 2009 5:32 pm
Re: USB Power
The short answer to the question is yes*.
The long answer is that if your device follows the usb2 spec, and the computer follows the usb2 spec, and the power supply attached to the device can supply enough power for the computer and all attached devices, then yes.
So, I'm just going to trust that both devices adhere to the usb2 spec, because they're both clearly labeled usb2, and to do so and not follow the spec would be false advertising on someone's part.
That leaves the power supply which would have to support, lets see... 2.5w max per port * 6 usb ports on the device == 15w total usb power? Plus the max 8w from the computer itself == 23 watts? (Unless the disk also consumes extra power)
23w / 12v = about 2amps, which is nothing, according to a quick survey of my 'spare parts bin' that comes up with half a dozen old wall-warts that could easily handle that much power. I'm sure Irads will come along shortly to tell us that the power supply the device ships with can easily handle such a load.
Mind you, to achieve this level of usb power use, you'd have to be using one of those new multi-port digital toasters that optically monitors the 'brown level' of the bread and can very heat levels across it's surface to assure an even toasting. Or just a lot of high rpm disks I guess.
-Fluffy
*NB: The only factual matter in this post is the math, which does not apply to this product specifically. Everything else is intended as humor.
The long answer is that if your device follows the usb2 spec, and the computer follows the usb2 spec, and the power supply attached to the device can supply enough power for the computer and all attached devices, then yes.
So, I'm just going to trust that both devices adhere to the usb2 spec, because they're both clearly labeled usb2, and to do so and not follow the spec would be false advertising on someone's part.
That leaves the power supply which would have to support, lets see... 2.5w max per port * 6 usb ports on the device == 15w total usb power? Plus the max 8w from the computer itself == 23 watts? (Unless the disk also consumes extra power)
23w / 12v = about 2amps, which is nothing, according to a quick survey of my 'spare parts bin' that comes up with half a dozen old wall-warts that could easily handle that much power. I'm sure Irads will come along shortly to tell us that the power supply the device ships with can easily handle such a load.
Mind you, to achieve this level of usb power use, you'd have to be using one of those new multi-port digital toasters that optically monitors the 'brown level' of the bread and can very heat levels across it's surface to assure an even toasting. Or just a lot of high rpm disks I guess.
-Fluffy
*NB: The only factual matter in this post is the math, which does not apply to this product specifically. Everything else is intended as humor.
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irads
Re: USB Power
We provide fit-PC2 with a 12V 1.5A power supply.
You can safely feed 2 external 2.5" disks, keyboard and mouse off that.
If you plan to attach external devices totaling over 6W you would better use a powered hub.
You can safely feed 2 external 2.5" disks, keyboard and mouse off that.
If you plan to attach external devices totaling over 6W you would better use a powered hub.
Re: USB Power
I realize this post is answered and older but I wanted to add that I have used said DVD-R drive and it works fine. Even with my ipod and keyboard/mouse connected.