Electronics > Beginners
USB 2 or USB 3
masster:
HelloI have a simple question to ask.I have this 512 GB flash memory USB 3.0 stick made by Kingston (HyperX Savage). The male USB connector has only 4 pins.From my knowledge the USB 3.0 standard mentions the connector should have 5 more pins for extra signals.My question is: with only 4 pins (as for USB 2.0) will the stick work at full USB 3.0 specifications?
timgiles:
No, if you have only 4 pins then there is only 1 pair of differential pairs which means USB 2. USB 3 requires a further two pairs of differential pairs, one for receiving and one for return of data.
Strange that Kingston state it is a USB 3.0 device.... most likely their marketing department deciding to stretch the compatibility built in to the USB 3 standard to almost breaking point...
Lusu:
It should have another row of pins behind the 4 that you see in front, see here for example: http://sc01.alicdn.com/kf/HTB100HuKFXXXXcXXXXXq6xXFXXXS/USB3-0-connector.jpg
If it has only 4 pins, it is USB 2...
"The connector has the same physical configuration as its predecessor but with five more pins.
The VBUS, D−, D+, and GND pins are required for USB 2.0 communication. The additional USB 3.0 pins are two differential pairs and one ground (GND_DRAIN). The two additional differential pairs are for SuperSpeed data transfer; they are used for full duplex SuperSpeed signaling. The GND_DRAIN pin is for drain wire termination and to control EMI and maintain signal integrity." (https://en.wikipedia.org/wiki/USB_3.0)
masster:
Thank you for the answers.Update: Out of frustration and in order to be 100% sure, I opened the stick and to my surprise the PCB has pads for accommodating 9 pins but only 4 pins |O from the USB connector are soldered. Plus, minus, D+ and D-.
I am wondering if the remaining 5 pins of the male connector are derived from the other 4 pins by pulling them to high or low with resistors. I see a bunch of resistors on PCB around those extra 5 pads.
Lusu:
They are most likely floating, since they are not connected. The 0 ohms resistors on the back probably shunt the extra USB3 lines of the chip to the ground, the chip seems to have the traces for USB3...
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