M
Mark Solesbury
Guest
Does any one know the avalaible power and curent you can get out of a USB 2
port on a laptop?
Mark
87 RR V8 EFI
port on a laptop?
Mark
87 RR V8 EFI
This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
P
Paul S. Brown
Guest
Mark Solesbury wrote:
> Does any one know the avalaible power and curent you can get out of a USB
> 2 port on a laptop?
>
>
500mA - about 4W in total power.
P.
--
If Mind over Matter is a Matter of Course
Does it Matter if Nobody Minds?
> Does any one know the avalaible power and curent you can get out of a USB
> 2 port on a laptop?
>
>
500mA - about 4W in total power.
P.
--
If Mind over Matter is a Matter of Course
Does it Matter if Nobody Minds?
M
Mark Solesbury
Guest
I have a PSTwo, and a USB tv in card.
My plan was to run the now 12V console of a USB port.............
Well thats that out of the Q then!!
Cheers,
Mark.
"Paul S. Brown" <[email protected]> wrote in message
news:[email protected]...
> Mark Solesbury wrote:
>
> > Does any one know the avalaible power and curent you can get out of a
USB
> > 2 port on a laptop?
> >
> >
>
> 500mA - about 4W in total power.
>
> P.
>
> --
> If Mind over Matter is a Matter of Course
> Does it Matter if Nobody Minds?
My plan was to run the now 12V console of a USB port.............
Well thats that out of the Q then!!
Cheers,
Mark.
"Paul S. Brown" <[email protected]> wrote in message
news:[email protected]...
> Mark Solesbury wrote:
>
> > Does any one know the avalaible power and curent you can get out of a
USB
> > 2 port on a laptop?
> >
> >
>
> 500mA - about 4W in total power.
>
> P.
>
> --
> If Mind over Matter is a Matter of Course
> Does it Matter if Nobody Minds?
M
Martin Edwards
Guest
Nope, and you won't get a Jump Lead adapter either!
"Mark Solesbury" <[email protected]> wrote in message
news:1I%[email protected]...
> I have a PSTwo, and a USB tv in card.
>
> My plan was to run the now 12V console of a USB port.............
>
> Well thats that out of the Q then!!
>
> Cheers,
>
> Mark.
>
>
> "Paul S. Brown" <[email protected]> wrote in message
> news:[email protected]...
> > Mark Solesbury wrote:
> >
> > > Does any one know the avalaible power and curent you can get out of a
> USB
> > > 2 port on a laptop?
> > >
> > >
> >
> > 500mA - about 4W in total power.
> >
> > P.
> >
> > --
> > If Mind over Matter is a Matter of Course
> > Does it Matter if Nobody Minds?
>
>
"Mark Solesbury" <[email protected]> wrote in message
news:1I%[email protected]...
> I have a PSTwo, and a USB tv in card.
>
> My plan was to run the now 12V console of a USB port.............
>
> Well thats that out of the Q then!!
>
> Cheers,
>
> Mark.
>
>
> "Paul S. Brown" <[email protected]> wrote in message
> news:[email protected]...
> > Mark Solesbury wrote:
> >
> > > Does any one know the avalaible power and curent you can get out of a
> USB
> > > 2 port on a laptop?
> > >
> > >
> >
> > 500mA - about 4W in total power.
> >
> > P.
> >
> > --
> > If Mind over Matter is a Matter of Course
> > Does it Matter if Nobody Minds?
>
>
M
Mark Solesbury
Guest
> Nope, and you won't get a Jump Lead adapter either!
>
What ? Surely 500mA is enough to run a knackerd starter motor with a sticky
solenoid and turn a V8 over!!
> "Mark Solesbury" <[email protected]> wrote in message
> news:1I%[email protected]...
> > I have a PSTwo, and a USB tv in card.
> >
> > My plan was to run the now 12V console of a USB port.............
> >
> > Well thats that out of the Q then!!
> >
> > Cheers,
> >
> > Mark.
> >
> >
> > "Paul S. Brown" <[email protected]> wrote in message
> > news:[email protected]...
> > > Mark Solesbury wrote:
> > >
> > > > Does any one know the avalaible power and curent you can get out of
a
> > USB
> > > > 2 port on a laptop?
> > > >
> > > >
> > >
> > > 500mA - about 4W in total power.
> > >
> > > P.
> > >
> > > --
> > > If Mind over Matter is a Matter of Course
> > > Does it Matter if Nobody Minds?
> >
> >
>
>
S
Steve Taylor
Guest
Mark Solesbury wrote:
>>Nope, and you won't get a Jump Lead adapter either!
>>
>
>
> What ? Surely 500mA is enough to run a knackerd starter motor with a sticky
> solenoid and turn a V8 over!!
>
Funny you should be talking about USB current, because I am up to my
eyes in USB documentation designing a new system at work.
AFAIK, although according to the USB spec, USB devices aren't supposed
to draw more than 500mA**, and only then if they ask for it nicely,
there are few USB ports that actually implement it properly. That said,
you may well blow fuses set in the PCB design if you try it.
Steve
** From Maxim Semiconductors app note 3241.
What Your Mom Didn't Tell You About USB
With any standard, it's interesting to see how actual practice diverges
from the printed spec or how undefined parts of the spec take shape.
Though USB is, with little doubt, one of the best thought out, reliable,
and useful standards efforts in quite some time, it has not been immune
to the impact of the real world. Some observed USB characteristics that
may not be obvious, yet can influence power designs, are:
* USB ports do NOT limit current. Though the USB spec provides
details about how much current a USB port must supply, there are
mile-wide limits on how much it might supply. Though the upper limit
specifies that the current never exceed 5A, but a wise designer should
not rely on that. In any case, a USB port can never be counted on to
limit its output current to 500mA, or any amount near that. In fact,
output current from a port often exceeds several Amps since multi-port
systems (like PCs) frequently have only one protection device for all
ports in the system. The protection device is set above the TOTAL power
rating of all the ports. So a four-port system may supply over 2A from
one port if the other ports are not loaded. Furthermore, while some PCs
use 10-20% accurate IC-based protection, other will use much less
accurate poly-fuses (fuses that reset themselves) that will not trip
until the load is 100% or more above the rating.
* USB Ports rarely (never) turn off power: The USB spec is not
specific about this, but it is sometimes believed that USB power may be
disconnected as a result of failed enumeration, or other software or
firmware problems. In actual practice, no USB host shuts off USB power
for anything other that an electrical fault (like a short). There may an
exception to this statement, but I have yet to see it. Notebook and
motherboard makers are barely willing to pay for fault protection, let
alone smart power switching. So no matter what dialog takes place (or
does not take place) between a USB peripheral and host, 5V (at either
500mA or 100mA, or even maybe 2A or more) will be available. This is
born out by the appearance in the market of USB powered reading lights,
coffee mug warmers, and other similar items that have no communication
capability. They may not be "compliant," but they do function.
>>Nope, and you won't get a Jump Lead adapter either!
>>
>
>
> What ? Surely 500mA is enough to run a knackerd starter motor with a sticky
> solenoid and turn a V8 over!!
>
Funny you should be talking about USB current, because I am up to my
eyes in USB documentation designing a new system at work.
AFAIK, although according to the USB spec, USB devices aren't supposed
to draw more than 500mA**, and only then if they ask for it nicely,
there are few USB ports that actually implement it properly. That said,
you may well blow fuses set in the PCB design if you try it.
Steve
** From Maxim Semiconductors app note 3241.
What Your Mom Didn't Tell You About USB
With any standard, it's interesting to see how actual practice diverges
from the printed spec or how undefined parts of the spec take shape.
Though USB is, with little doubt, one of the best thought out, reliable,
and useful standards efforts in quite some time, it has not been immune
to the impact of the real world. Some observed USB characteristics that
may not be obvious, yet can influence power designs, are:
* USB ports do NOT limit current. Though the USB spec provides
details about how much current a USB port must supply, there are
mile-wide limits on how much it might supply. Though the upper limit
specifies that the current never exceed 5A, but a wise designer should
not rely on that. In any case, a USB port can never be counted on to
limit its output current to 500mA, or any amount near that. In fact,
output current from a port often exceeds several Amps since multi-port
systems (like PCs) frequently have only one protection device for all
ports in the system. The protection device is set above the TOTAL power
rating of all the ports. So a four-port system may supply over 2A from
one port if the other ports are not loaded. Furthermore, while some PCs
use 10-20% accurate IC-based protection, other will use much less
accurate poly-fuses (fuses that reset themselves) that will not trip
until the load is 100% or more above the rating.
* USB Ports rarely (never) turn off power: The USB spec is not
specific about this, but it is sometimes believed that USB power may be
disconnected as a result of failed enumeration, or other software or
firmware problems. In actual practice, no USB host shuts off USB power
for anything other that an electrical fault (like a short). There may an
exception to this statement, but I have yet to see it. Notebook and
motherboard makers are barely willing to pay for fault protection, let
alone smart power switching. So no matter what dialog takes place (or
does not take place) between a USB peripheral and host, 5V (at either
500mA or 100mA, or even maybe 2A or more) will be available. This is
born out by the appearance in the market of USB powered reading lights,
coffee mug warmers, and other similar items that have no communication
capability. They may not be "compliant," but they do function.
T
Tom Woods
Guest
On Sun, 12 Dec 2004 22:35:23 +0000, Steve Taylor
<[email protected]> wrote:
>Mark Solesbury wrote:
>>>Nope, and you won't get a Jump Lead adapter either!
>>>
>>
>>
>> What ? Surely 500mA is enough to run a knackerd starter motor with a sticky
>> solenoid and turn a V8 over!!
>>
>
>Funny you should be talking about USB current, because I am up to my
>eyes in USB documentation designing a new system at work.
>
>AFAIK, although according to the USB spec, USB devices aren't supposed
>to draw more than 500mA**, and only then if they ask for it nicely,
>there are few USB ports that actually implement it properly. That said,
>you may well blow fuses set in the PCB design if you try it.
You can get powered USB hub's can't you?. Would it not be possible to
pull more current out of one of them? (and also cheaper to replace if
you try to pull too much and break stuff!)
<[email protected]> wrote:
>Mark Solesbury wrote:
>>>Nope, and you won't get a Jump Lead adapter either!
>>>
>>
>>
>> What ? Surely 500mA is enough to run a knackerd starter motor with a sticky
>> solenoid and turn a V8 over!!
>>
>
>Funny you should be talking about USB current, because I am up to my
>eyes in USB documentation designing a new system at work.
>
>AFAIK, although according to the USB spec, USB devices aren't supposed
>to draw more than 500mA**, and only then if they ask for it nicely,
>there are few USB ports that actually implement it properly. That said,
>you may well blow fuses set in the PCB design if you try it.
You can get powered USB hub's can't you?. Would it not be possible to
pull more current out of one of them? (and also cheaper to replace if
you try to pull too much and break stuff!)
P
Paul S. Brown
Guest
Tom Woods wrote:
> On Sun, 12 Dec 2004 22:35:23 +0000, Steve Taylor
> <[email protected]> wrote:
>
>>Mark Solesbury wrote:
>>>>Nope, and you won't get a Jump Lead adapter either!
>>>>
>>>
>>>
>>> What ? Surely 500mA is enough to run a knackerd starter motor with a
>>> sticky solenoid and turn a V8 over!!
>>>
>>
>>Funny you should be talking about USB current, because I am up to my
>>eyes in USB documentation designing a new system at work.
>>
>>AFAIK, although according to the USB spec, USB devices aren't supposed
>>to draw more than 500mA**, and only then if they ask for it nicely,
>>there are few USB ports that actually implement it properly. That said,
>>you may well blow fuses set in the PCB design if you try it.
>
> You can get powered USB hub's can't you?. Would it not be possible to
> pull more current out of one of them? (and also cheaper to replace if
> you try to pull too much and break stuff!)
No, because the spec says 500mA per device.......
The point of the powered hub is to deliver that 500mA per port without
overtaxing the root hub on the machine it's attached to.
Sorry.
P.
--
If Mind over Matter is a Matter of Course
Does it Matter if Nobody Minds?
> On Sun, 12 Dec 2004 22:35:23 +0000, Steve Taylor
> <[email protected]> wrote:
>
>>Mark Solesbury wrote:
>>>>Nope, and you won't get a Jump Lead adapter either!
>>>>
>>>
>>>
>>> What ? Surely 500mA is enough to run a knackerd starter motor with a
>>> sticky solenoid and turn a V8 over!!
>>>
>>
>>Funny you should be talking about USB current, because I am up to my
>>eyes in USB documentation designing a new system at work.
>>
>>AFAIK, although according to the USB spec, USB devices aren't supposed
>>to draw more than 500mA**, and only then if they ask for it nicely,
>>there are few USB ports that actually implement it properly. That said,
>>you may well blow fuses set in the PCB design if you try it.
>
> You can get powered USB hub's can't you?. Would it not be possible to
> pull more current out of one of them? (and also cheaper to replace if
> you try to pull too much and break stuff!)
No, because the spec says 500mA per device.......
The point of the powered hub is to deliver that 500mA per port without
overtaxing the root hub on the machine it's attached to.
Sorry.
P.
--
If Mind over Matter is a Matter of Course
Does it Matter if Nobody Minds?
R
Ralph A. Schmid, DK5RAS
Guest
Tom Woods <[email protected]> wrote:
>You can get powered USB hub's can't you?. Would it not be possible to
>pull more current out of one of them? (and also cheaper to replace if
>you try to pull too much and break stuff!)
Modern USB ports usually have a self resetting "polyswitch" fuse. So
nothing happens...when the developers did their homework
regards - Ralph
--
Want to get in touch? http://www.radio-link.net/whereisralph.txt
>You can get powered USB hub's can't you?. Would it not be possible to
>pull more current out of one of them? (and also cheaper to replace if
>you try to pull too much and break stuff!)
Modern USB ports usually have a self resetting "polyswitch" fuse. So
nothing happens...when the developers did their homework
regards - Ralph
--
Want to get in touch? http://www.radio-link.net/whereisralph.txt
S
Steve Taylor
Guest
Ralph A. Schmid, DK5RAS wrote:
> Tom Woods <[email protected]> wrote:
>
>
>>You can get powered USB hub's can't you?. Would it not be possible to
>>pull more current out of one of them? (and also cheaper to replace if
>>you try to pull too much and break stuff!)
>
>
> Modern USB ports usually have a self resetting "polyswitch" fuse. So
> nothing happens...when the developers did their homework
....if they did their homework, a USB device can only draw 100mA, unless
it asks for more and the system can grant it, up to 500mA..
Then again, you can get coffee warmers that plug into USB ports....
Steve
> Tom Woods <[email protected]> wrote:
>
>
>>You can get powered USB hub's can't you?. Would it not be possible to
>>pull more current out of one of them? (and also cheaper to replace if
>>you try to pull too much and break stuff!)
>
>
> Modern USB ports usually have a self resetting "polyswitch" fuse. So
> nothing happens...when the developers did their homework
....if they did their homework, a USB device can only draw 100mA, unless
it asks for more and the system can grant it, up to 500mA..
Then again, you can get coffee warmers that plug into USB ports....
Steve
S
Stuart Adair
Guest
Hold on a minute - You lot gave me a right earful for posting some details
of an XJS part I have for sale. Mr Solebury here posts a question that is
not even about cars (No offence sir) and not only do you lot not chastise
him - You positively help him with good advice.
Starting to think you lot have something against me.
Stu
"Steve Taylor" <[email protected]> wrote in message
news:[email protected]...
> Ralph A. Schmid, DK5RAS wrote:
>> Tom Woods <[email protected]> wrote:
>>
>>
>>>You can get powered USB hub's can't you?. Would it not be possible to
>>>pull more current out of one of them? (and also cheaper to replace if
>>>you try to pull too much and break stuff!)
>>
>>
>> Modern USB ports usually have a self resetting "polyswitch" fuse. So
>> nothing happens...when the developers did their homework
>
> ...if they did their homework, a USB device can only draw 100mA, unless it
> asks for more and the system can grant it, up to 500mA..
>
> Then again, you can get coffee warmers that plug into USB ports....
>
> Steve
of an XJS part I have for sale. Mr Solebury here posts a question that is
not even about cars (No offence sir) and not only do you lot not chastise
him - You positively help him with good advice.
Starting to think you lot have something against me.
Stu
"Steve Taylor" <[email protected]> wrote in message
news:[email protected]...
> Ralph A. Schmid, DK5RAS wrote:
>> Tom Woods <[email protected]> wrote:
>>
>>
>>>You can get powered USB hub's can't you?. Would it not be possible to
>>>pull more current out of one of them? (and also cheaper to replace if
>>>you try to pull too much and break stuff!)
>>
>>
>> Modern USB ports usually have a self resetting "polyswitch" fuse. So
>> nothing happens...when the developers did their homework
>
> ...if they did their homework, a USB device can only draw 100mA, unless it
> asks for more and the system can grant it, up to 500mA..
>
> Then again, you can get coffee warmers that plug into USB ports....
>
> Steve
A
Austin Shackles
Guest
On or around Mon, 13 Dec 2004 18:29:19 +0000 (UTC), "Stuart Adair"
<[email protected]> enlightened us thusly:
>Hold on a minute - You lot gave me a right earful for posting some details
>of an XJS part I have for sale. Mr Solebury here posts a question that is
>not even about cars (No offence sir) and not only do you lot not chastise
>him - You positively help him with good advice.
>
>Starting to think you lot have something against me.
It is flagged "very OT", which allows anyone who don't want to look to
ignore it.
IIRC, yours was neither OT nor FS or any such?
Personally, I look at most things, but some folk don't want to do that.
<[email protected]> enlightened us thusly:
>Hold on a minute - You lot gave me a right earful for posting some details
>of an XJS part I have for sale. Mr Solebury here posts a question that is
>not even about cars (No offence sir) and not only do you lot not chastise
>him - You positively help him with good advice.
>
>Starting to think you lot have something against me.
It is flagged "very OT", which allows anyone who don't want to look to
ignore it.
IIRC, yours was neither OT nor FS or any such?
Personally, I look at most things, but some folk don't want to do that.
M
Mark Solesbury
Guest
> Hold on a minute - You lot gave me a right earful for posting some details
> of an XJS part I have for sale. Mr Solebury here posts a question that is
> not even about cars (No offence sir) and not only do you lot not chastise
> him - You positively help him with good advice.
Hand Bags a 12 paces!!!!!
S
Steve Taylor
Guest
Stuart Adair wrote:
> Hold on a minute - You lot gave me a right earful for posting some details
> of an XJS part I have for sale. Mr Solebury here posts a question that is
> not even about cars (No offence sir) and not only do you lot not chastise
> him - You positively help him with good advice.
The one who said "Spam" was hardly supported here though was he ?
Cheer up you old bugger.
Steve
> Hold on a minute - You lot gave me a right earful for posting some details
> of an XJS part I have for sale. Mr Solebury here posts a question that is
> not even about cars (No offence sir) and not only do you lot not chastise
> him - You positively help him with good advice.
The one who said "Spam" was hardly supported here though was he ?
Cheer up you old bugger.
Steve
R
Ralph A. Schmid, DK5RAS
Guest
Steve Taylor <[email protected]> wrote:
>...if they did their homework, a USB device can only draw 100mA, unless
>it asks for more and the system can grant it, up to 500mA..
The polyswitch is there to prevent the system from damage when more
than 500mA are drawn. Of course usually it does not come to this
point, because the system recognizes a power surge and shuts off the
supply.
regards - Ralph
--
Want to get in touch? http://www.radio-link.net/whereisralph.txt
>...if they did their homework, a USB device can only draw 100mA, unless
>it asks for more and the system can grant it, up to 500mA..
The polyswitch is there to prevent the system from damage when more
than 500mA are drawn. Of course usually it does not come to this
point, because the system recognizes a power surge and shuts off the
supply.
regards - Ralph
--
Want to get in touch? http://www.radio-link.net/whereisralph.txt
P
Peter R.
Guest
On Sun, 12 Dec 2004 17:36:56 GMT, "Mark Solesbury"
<[email protected]> wrote:
>Does any one know the avalaible power and curent you can get out of a USB 2
>port on a laptop?
>
>
>Mark
>
>87 RR V8 EFI
>
Why ? Do you want to run a winch off it ?
Peter R.
<[email protected]> wrote:
>Does any one know the avalaible power and curent you can get out of a USB 2
>port on a laptop?
>
>
>Mark
>
>87 RR V8 EFI
>
Why ? Do you want to run a winch off it ?
Peter R.
