This application note describes the output timing parameters for Altera® devices, explains how Altera defines tCO results, and presents techniques for calculating the output timing for your system. In addition, a sample DDR2 interface link is presented and analyzed for calculating output timing. Detailed timing information is available in the device handbooks and from the Quartus® II software. The timing information in the handbooks presumes a sample design and is specific to that one implementation for that device. Your implementation may be different, so you should obtain timing data that directly applies to your system by using the values reported by the Quartus II timing analyzer (TAN) or TimeQuest. When dealing with output timing parameters such as tCO, the Quartus II software is only aware of the FPGA-related timing components. The Quartus II software does not have information on the PCB or the receiving device. It is important to understand exactly what the tCO result parameters represent and to understand how to use the timing reported by the Quartus II software to determine complete system timing.