AOD270 USB 2.0 Power output for external HDD 2.5"?

16bit
16bit Member Posts: 12 New User

Hi,

 

I am currently looking at getting an external USB 2.0/3.0 HDD for data backup and extra storage.  

I note that many 2.5" external drives do not have their own power supply, but use the power supplied fromthe computers UBS port.

Are the USB 2.0 ports on the AOD 270 26Dkk powered sufficiently to deliver enough current to typical 2.5" external HDD?
The other question is whether or not the netbook power supply delivers enough current also?

I already have a wired mouse connected via USB,and may connect a Compact Flash card reader simultaneously to the HDD.

I believe I read that they carry 5V at 2A, which is standard I think, and external drives use up to around 1A on spin up, less in operation.  Feel free to correct me if any of that data is incorrect - it's what I have found around the net from less than perfect sources.

Thanks in advance.

Answers

  • 16bit
    16bit Member Posts: 12 New User

    I dunno where I got the above stats for USB power, but according to the designated spec, USB should deliver +5v and 500mA for devices, (with 100mA on first connection, later allowing more current after conversation).  

    More power (current) is available but onyl in charging mode, and that depends upon the manufacturer spec.

    I read in the service manual for this particular machine, a 2A current, so I assume that is for charging purposes.

    It seems strange that on Seagate's (one manufactuer I am looking at) website, there is no mention of current draw or wattage consumption, from which I could derrive current draw (Pw = Ia * Vv).  I've heard of some older drive using a 'Y' cable to utilise two USB ports, and thus 1A current, but I would like to be on the safe side.

  • 16bit
    16bit Member Posts: 12 New User

    Adding more info for what I have found.

    There is a Toshiba External USB 2.0 external  (2.5" actual drive), and the manufacturer claims it's power consumption is 5w.

    Now 5 w on a USB so, using Power = Current x Voltage:
    5 watt = ? amps X +5 volt
    Current = 1 Amp (1000mA)
    USB2.0 spec is 500mA, USB3.0 spec is 900mA.  

    Neither USB 2.0 or 3.0 spec is designed for that kind of current draw.  Am I missing something here?

    From readinga  bit more of people's own opinion on forums and threads, it would seem that on spin up of the drive current can get towards 1Amp, but in usage is generally less.

    Again, I want to play this safe, and am not going to get an external USB HDD with USB only power unless I have clarification that the netbook can sufficiently power it.

  • 16bit
    16bit Member Posts: 12 New User

    Really, no one have anything to contribute?

    Looking on Amazon or Overclockers it would appear ALL external USB2.0/3.0 HDD are 5400rpm and are bus-powered, usually with just 1 USB cable.

    There was only one or two I could find that were 7200rpm units and that had their own power supply/wall wart.

    I can't find too many powered USB hubs either, so that if the netbook delivered insufficient current, I could just hookup the hub in between.

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