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Bus power capacity?

Message #1 - Posted 2005/04/08 - aengster@gmail.com

Hello All,

Finished up my first month of honeymooning with my powerbook and been getting alot of productive use out of it.

Question -- How much power can these machines provide through the USB & FW bus (normally, in battle mode, etc.)? Been noticing the PB getting awfully hot if there are too many external gadgets drawing bus (FW & USB) power simultaneously, obviously...

Here's my setup (power hungry to begin with): G4, 15", 100gb drive, 2 gigs ram, 64meg graphics, setup optimized for performance, keyboard illuminated (for dark room settings), bluetooth mouse on, with & without power adapter plugged in. The application is multitrack live audio recording.

I would have liked to have had the A/D converter bus powered (it consumes 12 Watts, i.e. 1amp @ 12V) along with a bus (FW preferred, USB 2.0 otherwise) powered external HD but presently having to rethink this.

Powering all the externals with their own power adapters is doable but it would be nice to minimize such.

Nice machine!

Andy

P.S. Observation -- Noticed the machine runs relatively cooler not when air's allowed to freely circulate through the bottom even with a fan blowing air across the bottom but if she's sitting on a solid surface capable of aborbing the heat. Duh... :-)

P.S.S. Wondering if a little USB lamp will do the job with less strain than the illuminated keyboard. Hmmm...

Message #2 - Posted 2005/04/08 - Neill Massello

aengster@gmail.com wrote:

Question -- How much power can these machines provide through the USB & FW bus (normally, in battle mode, etc.)? Been noticing the PB getting awfully hot if there are too many external gadgets drawing bus (FW & USB) power simultaneously, obviously...

Here's my setup (power hungry to begin with): G4, 15", 100gb drive, 2 gigs ram, 64meg graphics, setup optimized for performance, keyboard illuminated (for dark room settings), bluetooth mouse on, with & without power adapter plugged in. The application is multitrack live audio recording.

I would have liked to have had the A/D converter bus powered (it consumes 12 Watts, i.e. 1amp @ 12V) along with a bus (FW preferred, USB 2.0 otherwise) powered external HD but presently having to rethink this.

According to Apple's Developer Note (2005-02-15) for the PowerBook 15, the USB ports provide 500 mA each at 5 Volts and the FireWire ports a combined maximum of 1.5 amps at 12.8 Volts.

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