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Thread: Powering a USB hub. What 5v regulator chip to use?

  1. #1
    FLAC
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    Powering a USB hub. What 5v regulator chip to use?

    I was wondering if someone can help me pick out a 5v voltage regulator chip to use to power my USB hub? I cant power it off the 5v rails because the M2 is a POS and the voltage drops too much even with a little load (so no more adding stuff to the 5v rail).

    Ideally I want something compact that I can mount to the inside of the hub. Linear regulators are cheap, but Im worried that it may get too hot. Anyone know of some good, simple switching regulator chips that are cheap? Ive found a few on eBay, but they are only 1 amp. I think ideally I would need 3 amps or more.

  2. #2
    Constant Bitrate
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    u can find alot of ipod/iphone/blackberry CAR ADAPTOR chargers with USB ports on them, hack it up wire it to the car's 12VOLT line, and get the 5volts regulated off the usb port on the car adaptor, it's easy to do and u can find them anywhere
    and they dont kill your battery either

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    Fiberoptic's Avatar
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    If budget wasn't an issue you could take a look at this.
    http://store.mp3car.com/DC_Powered_4..._p/adt-015.htm

  4. #4
    Raw Wave
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    How much current do you require?

    Hubs usually aren't much - usually 7805s at 1A are enough (for 2 pots @ 500mA each); that's under 10W of heat at 1A.

    Or their are the 3A & 5A versions....

    Heat is merely (V-5)xI where V = supply voltage & I = total current.

    (I'm assuming heatsinking, simplicity and cheapness is more important than a cooler SMPS etc? Most DC-DC converters are $20 upwards (5V/5A).)

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    Newbie Fuegomp3's Avatar
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    LM323K (TO-3) or LM323T (TO-220)

    5 volts, 3 Amp.

    Cheers,

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    Raw Wave pierrotm777's Avatar
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    Quote Originally Posted by Fuegomp3 View Post
    LM323K (TO-3) or LM323T (TO-220)

    5 volts, 3 Amp.

    Cheers,
    I prefer the to220 who are smaller than the to3 .
    If you want 5v/3a , please choose a component who can to support more , by exemple 5v/4a . never use a component to its limit !I is not good for the efficiency .

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    Thanks, Ill look into those. Ive got a 7 port hub, so I definitely dont want to limit myself to just 1 amp (otherwise I could just get a 7808 or LM317).

    Ideally I want to cram this regulator into my hub for a clean install, which probably wont work work well with a linear regulator that would require a huge heatsink. eg. If I was pulling 3 amps over a 7 volt drop (with a linear regulator), that's 21 watts of heat! Plus, I intend to run this off my 12v rails on the M2, so the less load I can put on that the better.

  8. #8
    Raw Wave pierrotm777's Avatar
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    Quote Originally Posted by nobb View Post
    Thanks, Ill look into those. Ive got a 7 port hub, so I definitely dont want to limit myself to just 1 amp (otherwise I could just get a 7808 or LM317).

    Ideally I want to cram this regulator into my hub for a clean install, which probably wont work work well with a linear regulator that would require a huge heatsink. eg. If I was pulling 3 amps over a 7 volt drop (with a linear regulator), that's 21 watts of heat! Plus, I intend to run this off my 12v rails on the M2, so the less load I can put on that the better.
    Usb can use 500ma by port . Also the max amp that you need is not 3A but 3.5A or 17,5W.

    example 1

    example 2

  9. #9
    Newbie Fuegomp3's Avatar
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    LM338K is a variable regulator, 5Amp.

  10. #10
    FLAC
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    Quote Originally Posted by pierrotm777 View Post
    Usb can use 500ma by port . Also the max amp that you need is not 3A but 3.5A or 17,5W.
    I know, but alot of my devices wont take up all of that 500mA, so I can probably get away with 3A.

    How can I tell if the LM338K is linear or switching? It's not mentioned in the datasheet.
    Edit: nvm, I searched eBay for the LM338K and some of the prebuilt regulators have huge honking heatsinks. Must be linear.

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