Insufficient current over USB ports

  • Thread starter Thread starter Man-wai Chang
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Man-wai Chang

I just discovered that the USB ports on my Asus M3N78-PRO motherboard
are not supplying sufficient current. The result: power-demanding USB
devices like a Canon USB 2.0 scanner and an iPod Touch 3 would appear
then disappear then appear then ... in the device list.

Isn't there a USB 2.0 standard for motherboard designers and
manufacturers to follow?

Or is it my Antec TruePower New 650W power supply?

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I just discovered that the USB ports on my Asus M3N78-PRO motherboard
are not supplying sufficient current. The result: power-demanding USB
devices like a Canon USB 2.0 scanner and an iPod Touch 3 would appear
then disappear then appear then ... in the device list.

Isn't there a USB 2.0 standard for motherboard designers and
manufacturers to follow?

Or is it my Antec TruePower New 650W power supply?
Click to expand...
Easy solution ... just get a PCI USB card and install it. They usually
have more power available than onboard USB. I plug one of these cards
into all my computers no matter how many onboard USB ports the
motherboard has. Far cheaper to pop a chip off a card than it is to pop
a chip off a motherboard. Did that recently to the onboard USB hub in my
Mac keyboard. When I dismantled the keyboard, the USB chip had exploded.
A bit too much current draw!
 
Man-wai Chang said:
I just discovered that the USB ports on my Asus M3N78-PRO motherboard
are not supplying sufficient current. The result: power-demanding USB
devices like a Canon USB 2.0 scanner and an iPod Touch 3 would appear
then disappear then appear then ... in the device list.

Isn't there a USB 2.0 standard for motherboard designers and
manufacturers to follow?

Or is it my Antec TruePower New 650W power supply?
Click to expand...

At one time, Asus motherboards had "USBPWR" jumpers, to select power
source. The options were +5V or +5VSB, as the powering rail. You
would use +5VSB, if the USB port connected to that jumper, was to be
used to "wake" the computer. For example, if you wanted to "wake on keyboard",
you'd set the jumper to +5VSB.

Recent motherboards, don't have those jumpers any more. You may find,
that the USB ports are powered by +5VSB.

The power supply label, has a current rating for +5VSB. It can be
on the order of 2 amps to 3 amps. If the motherboard uses 1 amp for
things like standby current for LAN or the like, that may leave 1 amp
minimum remaining for USB.

A USB2 device, can draw up to 500mA. If you have two of the heavier
loading USB2 devices, that would be 1 ampere total.

At the USB ports themselves, they're arranged in pairs. The Asus motherboard
may have one Polyfuse, connected to the two USB devices in a "stack of two"
connectors. The rating of the fuse is printed on top. I've got some
motherboards here, where I see "1.1" printed on the green Polyfuse.
If two 500mA devices are connected, I presume the automatic fuse
won't open. I've seen suggestions, that the USB stack not be
"policed" by that fuse, and the fuse is supposed to be set
a bit higher, as a means of hardware protection, rather than
policing the current draw to exactly 2x500mA = 1 ampere.

I can't say in your case, which of those mechanisms would be at work.

As Krypsis says, a USB2 PCI card, is an easy way to modify the power
distribution. As long as the USB2 PCI card draws power from +5V for
the ports, then you'd end up using a different rail on the power supply.
Some USB2 cards, have an "Aux" power connector on the end of the card,
which implies powering from +5V (just a guess). If the card costs $10,
and you have a free PCI slot in the system, it's worth a try.

Paul
 
Easy solution ... just get a PCI USB card and install it. They usually
have more power available than onboard USB. I plug one of these cards
into all my computers no matter how many onboard USB ports the
motherboard has. Far cheaper to pop a chip off a card than it is to pop
a chip off a motherboard. Did that recently to the onboard USB hub in my
Mac keyboard. When I dismantled the keyboard, the USB chip had exploded.
A bit too much current draw!
Click to expand...

Right now I am using a powered USB hub. I think another good solution is
to buy a POWERED PCIe USB 3 adaptor.

Anyway, I plan to upgrade my motherboard to one that has USB 3.0 ports.

--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.4
^ ^ 22:56:01 up 5 days 2:09 0 users load average: 0.09 0.05 0.06
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As Krypsis says, a USB2 PCI card, is an easy way to modify the power
distribution. As long as the USB2 PCI card draws power from +5V for
the ports, then you'd end up using a different rail on the power supply.
Some USB2 cards, have an "Aux" power connector on the end of the card,
which implies powering from +5V (just a guess). If the card costs $10,
and you have a free PCI slot in the system, it's worth a try.
Click to expand...

Now we should get *powered* USB 3 adaptor. :)

--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.4
^ ^ 22:56:01 up 5 days 2:09 0 users load average: 0.09 0.05 0.06
ä¸å€Ÿè²¸! ä¸è©é¨™! ä¸æ´äº¤! ä¸æ‰“交! ä¸æ‰“劫! ä¸è‡ªæ®º! è«‹è€ƒæ…®ç¶œæ´ (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
 
I just discovered that the USB ports on my Asus M3N78-PRO motherboard
are not supplying sufficient current. The result: power-demanding USB
devices like a Canon USB 2.0 scanner and an iPod Touch 3 would appear
then disappear then appear then ... in the device list.

Isn't there a USB 2.0 standard for motherboard designers and
manufacturers to follow?

Or is it my Antec TruePower New 650W power supply?
Click to expand...

Why not get a powered USB hub, or is that a separate problem?


Ah, I see you are as much a fan of Chinglish as I am--very fashionable
here in SE Asia.

RL
 
I have a Verbatim USB disk that has a Y-shaped cable to get extra power from
a second USB port. But it works on several PCs from just one USB port. It would
not work on a set top box, which only supplies the standard 500 mA. It appears
most PC USB ports pump out a bit extra, how much - who knows?
Click to expand...

The USB device reports its power requirement and the MB responds to a
limit of 100ma. Supposedly, the Control Panel lists the connected
item's power draw. On the MB USB jumper block, +5V or +5VSB is
possible, although the second is STBY power for USB system wake-up
events and not as well regulated as, preferably, selecting the first.

Here's what's bloody well here at 3.0.

USB standard of maintenance enforced by the USB Implementers Forum
(USB-IF):

For unconfigured devices, 150 mA of power is available, compared with
only 100 mA of power in USB 2.0. 150 mA is considered one unit load.
Configured devices are able to draw up to 6 unit loads, or 900 mA, a
significant increase from the 500 mA available in USB 2.0. The added
power allows for a broader range of devices to be bus-powered.

[Tons of simultaneous broadcasting arbitrations in less-impaired
restriction for disparate and earlier USB speed-locked, polled-event
devices. Unicasting.]

Link-level power management allows host or device to initiate
transitional lower-level power status state. Low-power levels are
configurable on the device level and the function level. [Based upon
interrupt events, whereas prior USB events were polled.]

Training, encoding, data scrambling [for line noise purposes], spread
spectral energy emissions for dissipating peak levels at a smaller
spectrum [EMC compliance], sideband low-frequency SuperSpeed USB3 (tm)
communications, source clock variances and design result buffer
elasticity (SKP implementation of dummy-data algorithms), LinkState
SS.Disabled, untrained, to operate in USB2 compliance only and w/out
SuperSpeed (protocol-driven streaming).

http://www.totalphase.com/products/
 
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