I/O Digital (IOD)

The IOD block interfaces with the FPGA fabric on one side and the IOA buffers on the other side. It deserializes and transfers input data to a lower core clock speed, or transfers lower-speed data from the fabric to the high-speed output clock domain, serializing it in the process. The I/O digital block works in conjunction with fast and low-skew clock networks. It also includes special clock dividers and other supported circuits to guarantee clock domain crossings. The I/O digital block deserializes high-speed DDR input data and transfers to FPGA fabric at lower speeds, and also serializes the lower speed FPGA fabric data and transfers to high-speed DDR output. For more information about IOD buffer and its use models, see IOD Features and User Modes, page 38.