Wish for 2nd generation Neo: USB 2.0

Joe Pfeiffer jjpfeifferjr at comcast.net
Mon Jan 22 02:11:07 CET 2007

Harald Welte writes:
>On Sun, Jan 21, 2007 at 06:56:30AM -0700, Joe Pfeiffer wrote:
>> Harald Welte writes:
>> >
>> >The main problem (with more powerful SoC) is not to provide a USB2.0
>> >host port in the device.  The main problem is power.  You need a pretty
>> >powerful DC/DC step-up converter to provide the 5V power supply to the
>> >USB bus.  And you have to provide at least up to 100mA - but to support
>> >all devices, 500mA.
>> I don't see this is a real problem -- 1.1 is supposed to do that too.
>> I'd have to look at the specs (USB and USBToGo) but I don't think
>> unpowered USB is actually compliant under any of them.
>It's not a technical problem per se.  
>It's just that you have to have one extra (powerful) DC/DC step-up
>converter in the device, something that vendors of phones (and other
>devices) usually don't put there for cost, battery life time and PCB
>footprint reasons.

That wasn't my point:  my point was that an unpowered USB 2.0
interface is no more noncompliant than the existing unpowered USB 1.1

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