Originally Posted by
mlepore
This has to be one of the most irritating and stupid design decisions - especially coupled with the fact that its really easy to not notice when the RAZR battery goes dead.
I have (twice now) had the RAZR die, and not have enough juice left to power up. Since it couldn't power up (fully) to "register" with the laptop, it wouldn't charge.
I know that its not a USB problem, because you can charge non USB phones off the USB port without them registering as a data link... its something special with the RAZR.
It could a factor of the USB spec and Mot laziness. USB, by default, delivers up to 100mA at 5V (500mW) to a device. If the device asks for more, up to 500mA (2.5W), the PC may deliver it. A normal USB hub can deliver a total of 500mA for all connected devices. Most computers should have more than one USB hub.
The device has to be powered to ask for more than 100mA. If a device tries to use too much power without asking, the PC can tell it to shut off. Any idiot circuit designer should be able to power the USB logic using the 100mA default power allocation (I've done it). Perhaps the RAZR's chipset is such that the chip that does the USB communications requires more than 100mA so that it cannot initially ask for more power, thus not working at all. (Just a guess).