Hi,

Is there anyone who ever thought about making a Full Speed USB HUB
IP core?

Why I need that?:
I am developing a USB interface for a high voltage device, and was
thinking about a way, to galvanically isolate the USB port (e.g. the PC)
from the rest of the circuit.
I know, that there are this kind of gadgets on the market, but they are
a bit expensive for my application (200..300USD).
I thing the best way to do this, is to implement the USB device into an
FPGA, and isolate the signals from the FPGA to the SIE. I will do this in
the future, but now I have to keep my USB chip, and put a (cheap)
isolation outside the circuit. This isolator could be a HUB implemented
in an FPGA with isolated lines to the SIE(s).

Please notify me, if you have a USB HUB IP core implementation in mind.

Tom

>>>>> "Paal" == Paal Tamas paal_to@freemail.hu> writes: Paal> Hi, Is there anyone who ever thought about making a Full Speed USB Paal> HUB IP core? Paal> Why I need that?: I am developing a USB interface for a high Paal> voltage device, and was thinking about a way, to galvanically Paal> isolate the USB port (e.g. the PC) from the rest of the circuit. Paal> I know, that there are this kind of gadgets on the market, but Paal> they are a bit expensive for my application (200..300USD). I Paal> thing the best way to do this, is to implement the USB device into Paal> an FPGA, and isolate the signals from the FPGA to the SIE. I will Paal> do this in the future, but now I have to keep my USB chip, and put Paal> a (cheap) isolation outside the circuit. This isolator could be a Paal> HUB implemented in an FPGA with isolated lines to the SIE(s). With high voltage devices, you normally want fibre optic cables as connections. I.m.h.o. USB is not the way to go. Perhaps use 1000 MBit fibre Ethernet or use optical transceivers with the serial devices incorporated in your FPGA. Bye -- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

What are the specs of your high voltage problem? 50V, 500V, 5000V, ...

Why not isolate the USB chip from the high voltage instead of trying to
isolate D+/D-?

Marc Reinig
System Solutions

Marc, The circuit works in the 50v...800v region. In the 50v...150v region it works fine without any galvanic isolation, but going higher with the system bus voltage, the USB communication fails. The USB functionality is integrated into the microcontroller, that's why I cannot put the isolation between the USB controller and the micro. The main problem is the ground loop, that can develope, if I directly connect the USB into the PC. (The PC ground and the power ground of the circuit is (at least) capacitively connected, so after the USB connection is made, another ground connection developes, making a big ground loop.) Tom Marc Reinig mreinig@pacbell.net> írta:
5000V, ...

Try http://www.semtech.com/pdf/rclamp0504m.pdf or similar products. Marc Reinig System Solutions

Thank you Mark! I'll compare that part with the one I am currently using. It is SN65220 from TI. Tom Marc Reinig mreinig@pacbell.net> írta: