I have a design using the XIO2001 to drive a compactPCI backplane. The PCI side of the chip is also conneceted to an Altera FPGA with the pins cofigured as unused with weak pullups. All works fine at 33MHz for up to 4 cPCI cards in the backplane. Once I add a 5th card (crate is not full), I can no longer enumerate any of the cards. If I slow the clock down to 25MHz with sel pin the system works again. This sounds like a loading issue. Does anyone have experiance with how many loads the chip can drive at 33MHz? Is there any way to make it drive harder?
Thanks
Frank