Comments on “NEC ready to sample 'world's first' USB 3.0 controller chip” • Register Hardware

Comments on: NEC ready to sample 'world's first' USB 3.0 controller chip

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Voltage #

By Anonymous Coward Posted Tuesday 19th May 2009 11:50 GMT

So, according to the block diagram... there's 3.3v and 1.05v going in.... I wonder if they're using a charge pump to generate the 5v for the usb port, or if they ommitted it in the diagram, or if it's not actually there.

OK, I appreciate that the 5v could be wired directly to the port, but the block diagram specifically mentions the port power control interface... maybe it's to enable the requests for more power and it interfaces with external power limiting hardware.

Glad to see USB3 is getting there though.

Backwards compatibility #

By Greg Posted Tuesday 19th May 2009 13:39 GMT

You mention that USB3 is back-compatible with USB2, as I expected. However, USB2 is back-compatible with USB1. Not knowing much about the inner workings of USB - will USB1 devices work on USB3 ports?

@Voltage #

By Simon Neill Posted Tuesday 19th May 2009 13:45 GMT

Port power control block is also marked as being external to the chip, so I'd guess at the chip controls the power without routing the power THROUGH the chip.

Port Voltage #

By Anonymous Coward Posted Tuesday 19th May 2009 13:50 GMT

IMHO, it would be pretty wasteful to put 5V through silicon simply to forward on to the physical ports, so I figure that voltage would be hardwired. But someone correct me if I'm wrong.

USB voltage #

By Anonymous Coward Posted Tuesday 19th May 2009 14:15 GMT

USB power is (almost?) always switched externally to the controller chip. Processes suitable for this high speed stuff don't make good, cheap, high current FETs. (Also, cheap manufacturers want to do the power control on the cheap, with (resettable) fuses, no current monitoring, no shutdown.

Ha this is sweet #

By Robert Posted Tuesday 19th May 2009 14:29 GMT

Nice

@Greg #

By Tony Smith, Editor, Reg Hardware Posted Tuesday 19th May 2009 14:53 GMT

USB 3.0 is backward compatible with USB 1.1 - that's, in part, what the USB 2.0 element is for.

The cabling's compatible too: USB 3.0 ports will interconnect with USB 1.1/2.0 connectors. Some, but not all, will work the other way round, but USB 3.0 device plugged into USB 2.0 port will only connect at 480Mb/s peak, not 5Gb/s.

@Greg #

By Adam Foxton Posted Tuesday 19th May 2009 15:10 GMT

All there for you in black and white on the drawing. There are separate USB3 and USB2 PHYs, with the USB2 PHY handling the High Speed / Full Speed / Low Speed (i.e. USB2, USB 1.1, USB 1) traffic.

So yes, a USB3 port will be able to interface with a piece of USB1 hardware.

If I remember correctly ... #

By Chris O'Shea Posted Tuesday 19th May 2009 15:15 GMT

I saw a diagram (possibly on here) which showed the USB3.0 socket as physically compatible with USB2.0/1.1 but with a small extension to the plug so you can plug a USB2.0 plug into a USB3.0 socket and it only meets up with USB2.0 compatible pins, but the 3.0 plug fits in further to pick up the faster data transfer pins.

So it's a full implementation of USB2.0 (including 1.1 which is part of the 2.0 spec) plus extra pins for the faster connection.

Of course it could all have changed since I last looked!