Hi eveyone,
I am designing a schematic for a project using Virtex-4 35 SX, and a platform flash for configuration (XCF16PVO48C). For the FPGA I use VCCO_0 = 3.3V, VCCAUX = 2.5V, and VCCINT = 1.2V. For the platform flash I use VCCO = VCCJ = 3.3V and VCCINT = 1.8V.
I want to use a 3.3V Jtag interface and the question is: I have connected the FPGA_INIT, FPGA_PROG_B and FPGA_DONE, and FPGA_CCLK to the Platform flash following the guide, but have trouble deciding the power supply to where I have to pull up these signals. Should it be 3.3V because VCCO_0 is 3.3V or should I pull them up to 2.5V because VCCAUX is 2.5V? Or it will work either ways? I have seen it done in the schematics of XILINX ML401_2_3 using 2.5V for pull up, although in the configuration guide it says to use VCCO_0.
Am I missing something here? Are those pins powered up by VCCO_0 or VCCAUX? Another user in this forum has told mehe is using the 3.3V tolerant configuration guide from SPARTAN-3 and he is doing the same to V4.
What is the optimum way to configure V4 in such a simple configuration scheme?
Thank you all in advance, -Tasos-