Cascade

The CASCADE attribute is set to NONE if the delay line is not cascaded. Cascading is used when a delay greater than 1.8 ns is required. The connections between delay elements are shown in the following figure. When using the IDELAYE5 and ODELAYE5 for cascading, the output is no longer available. Therefore, cascading delays is not supported for bidirectional buffers. The delay elements can only be cascaded within an IOB. Therefore, the maximum possible length of the delay is approximately 3.6 ns. The routes used to cascade IDELAYE5 and ODELAYE5 are dedicated, high-speed routes. The total fixed intrinsic insertion delay for an IDELAYE5 or ODELAYE5 cascade is the sum of the initial insertion delay plus the cascaded insertion delay. The following figure shows the proper port connections for a cascaded IDELAYE5 and ODELAYE5