On 07/12/2011 10:51, Andy Burns wrote:
Brian Mc wrote:

wrote:

: pins of the USB cable; if there is it trickle charges (many PC USB
: ports can only source a couple of hundred mA),

They are out of spec if they do this! 500mA is allowed from *ANY* PC USB
socket. I think the socket often switches off entirely - until something
else is plugged in - (and for charging not data) if you try to draw more
than that.

USB1 devices are only allowed 100mA (150mA for USB2) until they
negotiate higher power with the host (maximum 500mA for USB1 and 750mA
for USB2)

As mentioned by someone else, dedicted charging ports use combinations
of resistors on the data+/- pins to indicate even higher current is
available.



The mini USB connector has actually got 5 pins (if you look closely).
The 5th pin is normally not used but some charger systems use pull
up/down of this pin to determine charge rates.

Found this with a Motorola 'phone that would only charge off its own
charger, or off the computer when their (massive, sprawling) software
was installed.

Chris K

On Wed, 07 Dec 2011 11:22:41 +0000
Chris K wrote:

On 07/12/2011 10:51, Andy Burns wrote:
Brian Mc wrote:

wrote:

: pins of the USB cable; if there is it trickle charges (many PC
USB : ports can only source a couple of hundred mA),

They are out of spec if they do this! 500mA is allowed from *ANY*
PC USB socket. I think the socket often switches off entirely -
until something else is plugged in - (and for charging not data)
if you try to draw more than that.

USB1 devices are only allowed 100mA (150mA for USB2) until they
negotiate higher power with the host (maximum 500mA for USB1 and
750mA for USB2)

As mentioned by someone else, dedicted charging ports use
combinations of resistors on the data+/- pins to indicate even
higher current is available.



The mini USB connector has actually got 5 pins (if you look closely).
The 5th pin is normally not used but some charger systems use pull
up/down of this pin to determine charge rates.

Found this with a Motorola 'phone that would only charge off its own
charger, or off the computer when their (massive, sprawling) software
was installed.

Chris K

Where is the other end of that 5th pin? The big end of the USB cable
has 4 pins and a metal shield, the small one does indeed have 5 pins
and a metal shield.
--
Davey.

On 07/12/2011 11:27, Davey wrote:
On Wed, 07 Dec 2011 11:22:41 +0000
Chris wrote:

On 07/12/2011 10:51, Andy Burns wrote:
Brian Mc wrote:

wrote:

: pins of the USB cable; if there is it trickle charges (many PC
USB : ports can only source a couple of hundred mA),

They are out of spec if they do this! 500mA is allowed from *ANY*
PC USB socket. I think the socket often switches off entirely -
until something else is plugged in - (and for charging not data)
if you try to draw more than that.

USB1 devices are only allowed 100mA (150mA for USB2) until they
negotiate higher power with the host (maximum 500mA for USB1 and
750mA for USB2)

As mentioned by someone else, dedicted charging ports use
combinations of resistors on the data+/- pins to indicate even
higher current is available.



The mini USB connector has actually got 5 pins (if you look closely).
The 5th pin is normally not used but some charger systems use pull
up/down of this pin to determine charge rates.

Found this with a Motorola 'phone that would only charge off its own
charger, or off the computer when their (massive, sprawling) software
was installed.

Chris K

Where is the other end of that 5th pin? The big end of the USB cable
has 4 pins and a metal shield, the small one does indeed have 5 pins
and a metal shield.

It's not normally connected to anything in a standard USB cable.

Chris K

"Chris K" wrote in message
o.uk...


The mini USB connector has actually got 5 pins (if you look closely). The
5th pin is normally not used but some charger systems use pull up/down of
this pin to determine charge rates.

Found this with a Motorola 'phone that would only charge off its own
charger, or off the computer when their (massive, sprawling) software was
installed.

Chris K

Hi Chris.

http://www.usb.org/developers/docs/ecn1.pdf - page numbered 98 and
http://www.usb.org/developers/ontheg...mechanical.pdf slides 15,
16 and 20.
The extra pin is pin 4 which is the "ID" pin.

The info is easier to find in
http://en.wikipedia.org/wiki/USB
This says that the fifth pin (which is pin number 4) distinguishes between
the A and B plugs.

Hope this helps.

Best wishes,
Ian.



--- Posted via news://freenews.netfront.net/ - Complaints to ---

"Brian Mc" wrote in message
...
Norman Wells wrote:
: On the one hand, I'd have thought all USB connectors and compatible
: devices work on standard voltages etc. On the other, maybe there's a
: crucial difference in the power output needed to charge the different
: batteries.

: Anyone know the answer please?

I think so!

PC USB sockets supply 5V and are limited to supplying 5W of power max -
thus anything that can also be charged from a PC is interchangeable
between
different mains chargers (assuming the connectors match at the phone end!)

USB3 is 5W (1A) while USB1 and USB 2 are only 2.5W (500mA).

And anything connected to an unpowred USB1 or 2 hub can only draw 0.5W
(100mA).


Basically any USB socket/charger is OK for charging most devices.

I've known devices that draw the full 500mA to kill 300mA rated Apple USB
chargers after a few weeks of regular use.


The iPad/Ipad2, however, needs 10W to charge so that, when connected to a
normal PC USB, socket it does not charge - but it works for data and does
not damage the PC or the USB socket.

There's no guaranteeing what will happen if you try to draw too much current
from a USB socket.
Most nowadays have self resetting thermal fuses but you can't count on it.

--

Brian Gregory. (In the UK)

To email me remove the letter vee.