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Registered: ‎09-09-2008

Clock frequency in USB PHY to SIE interface.

I am using xilinx IP for USB 2.0. It's name is XPS Universal Serial Bus 2.0 Device (v1.00a).

It mentions that for high speed operations clock of 60MHz frequency should be

supplied to the SIE by the PHY. But it doesn't say anything about the Full speed (FS) operation (12Mbits/sec) as to

what clock frequency should be used there. The datasheet mentions that it is ULPI (Revision 1.1 ) compliant but even that

document(ULPI 1.1) mentions only one frequency i.e. 60 MHz.

  If somebody has already worked on imlementing ULPI protocol on PHY side for the full speed or has some

knowledge about it then please guide me. Should it be 1.5MHz(12 / 8) or something else? Any suggestion will be welcomed. 

Thanking in advance,


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Registered: ‎12-10-2008

Hi Kuldeep,

I'm Technical Marketing from STMicroelectronics. I understand you are using a XILINX product where High Speed Controller(VHDL) is embedded and you should need external PHY(Phisical Layer) with ULPI Bus.

What is the XILINX P/N are you using?

What is the final purpose?


We have these kind on products:





ULPI Bus 8bit have a ULPI Clock 60MHz generated from our device vs Processor.

Our device need a "chip" clock from digital square wave of 19.2MHz or 26MHz.


Best Regards, 

Carmelo Battaglia


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