Thanks James, With the iPod Touch ... Inside the ipod Touch is its own charging regulator circuit. It will only take as much amperage as the battery/regulator will allow. Any USB port that can supply at least the correct amount specified current at the proper regulated voltage will work.
I "think" on my MacBook Pro the rear USB port, the one nearest the screen, is in fact already on an internal hub, shared with everything USB inside the case: the keyboard, the Bluetooth, the trackpad, the iSight camera and the infra-red receiver. I would suspect that adding a four way hub to this is bound to end in disaster. From the Apple Developer Reference Library : “The USB ports support 500 (mA) at 5 V for 2.5 W power per port. ” MacBooks and MacBook Pros and Minis are said to have eight USB ports like the Pros, etc However, power draw and how it varies across ports, with one port on each MacBook being the high-power high-current-draw port, is mentioned. (The single port on the MacBook Air is high-current-draw.)" USB Product-Specific Details <http://developer.apple.com/legacy/mac/library/documentation/HardwareDrivers/Conceptual/HWTech_USB/Articles/usb_implementation.html#//apple_ref/doc/uid/TP40003902> Overview of USB on Macintosh Computers <http://developer.apple.com/legacy/mac/library/documentation/HardwareDrivers/Conceptual/HWTech_USB/Articles/usb_concepts.html#//apple_ref/doc/uid/TP40003901> Cheers, Ronni On 17/01/2010, at 2:11 PM, James / Hans Kunz wrote: > hi Ronni thanks for that info > it looks alike the keyboeard/ir/trackpad are using only 40ma of the 500ma > available, i can imagine that a camera suck the 500ma which means no further > power avaiable on this port, it seems the bluetooth is switched off thus the > 0ma = no load > generally yes not all usb ports are equal > it is a special circuit that controls the power consumption of each port & if > the limit is exeeded then this circuit (electronic fuse) shuts down the power > to the port, in most cases causeing failure of the connected gadget, if a > port is not delivering power you may still use that port for data transfer > through an externally powered hub, or selfpowered units (most > printers/harddisks) > in some cases a loose socket causes a failure (would'nt be the first usb port > i resoldered) > cheers James > > On 17/01/2010, at 9:26, Ronda Brown wrote: > >> >> Hi James, >> >> My MacBook Pro, has 3 USB Ports. The one I mentioned below is the High Speed >> USB Port 'Built-in iSight'. >> This Port has 500 (mA) Current Available & 500 (mA) Current Required. >> >> The USB Port - Apple Internal Keyboard / Trackpad / IR Receiver >> has 500 (mA) Current Available & 40 (mA) Current Required. >> >> The USB Port - Bluetooth USB Host Controller >> has 500 (mA) Current Available & 0 (mA) current required. >> >> This is your field, I don't profess to understand it, I was only pointing >> out that "All USB Ports are Not Equal". >> >> Cheers, >> Ronni >> >> On 17/01/2010, at 9:06 AM, James / Hans Kunz wrote: >> >>> hi Ronni >>> 500ma av & 500ma req that's really is a tight fit so i'm not suprised if >>> there is a on/off/on/off effect...... >>> the required power should be clearly below of what's available for reliable >>> steady work & you say "at least" which would confirm that my guess is >>> right, then in the beginning of the charge cycle any charger take more >>> power then towards the end of a cycle >>> James >>> >>> On 16/01/2010, at 16:39, Ronda Brown wrote: >>> >>>> >>>> Hi James, >>>> >>>> This is why I suggested to Kevin to check in System Profiler all his USB >>>> ports. >>>> System Profiler will show him what the Current Available, Current Required >>>> & speed. >>>> Similar to this: >>>> Current Available (mA): 500 >>>> Current Required (mA): 500 >>>> Speed: Up to 480 Mb/sec >>>> >>>> The iPod Touch requires at least 500 mA for proper charging as well as >>>> voltage within specification. >>>> >>>> Cheers, >>>> Ronni >>>> >>>> On 16/01/2010, at 4:25 PM, James / Hans Kunz wrote: >>>> >>>>> there is a strong possibility that the usb port you are using delivers >>>>> only 100ma which is not enough for recharge, it has nothing to do with >>>>> speed only with the 5v power coming out of the usb, "high powered" >>>>> equipment (chargers, harddisks) should not run directly of a usb port any >>>>> way......(if you overload the usb port shuts down) a external!!!!powered >>>>> usb hub could be a solution aswell >>>>> some dark world pcs front give you the same trouble & if you connect to a >>>>> backside port all is fine >>>>> try all usb ports i'm sure one gives the power for your recharging >>>>> James >>>>> >>>>> On 16/01/2010, at 11:25, KEVIN Lock wrote: >>>>> >>>>>> >>>>>> My wife's new iPod Touch will only charge using USB on her MacBook, not >>>>>> on our iMac. >>>>>> >>>>>> I have tried different USB ports, a powered hub, but no go. Both >>>>>> machines are running 10.4.11 with plenty of RAM. >>>>>> >>>>>> Not a big problem, but it is interesting...any ideas for me? >>>>>> >>>>>> Regards >>>>>> >>>>>> Kevin -- The WA Macintosh User Group Mailing List -- Archives - <http://www.wamug.org.au/mailinglist/archives.shtml> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml> Unsubscribe - <mailto:wamug-unsubscr...@wamug.org.au>
