Agilex™ 7 General-Purpose I/O User Guide: M-Series

ID 772138
Date 7/08/2024
Public
Document Table of Contents

6.7.2. Delay Elements

The Quartus® Prime software does not automatically set delay elements to maximize slack in the I/O timing analysis. To close the timing or maximize slack, set the delay elements manually in the Quartus® Prime settings file (.qsf).
Table 55.  Delay Elements .qsf AssignmentsSpecify these assignments in the .qsf to access the delay elements.
Delay Element .qsf Assignment
Input Delay Element set_instance_assignment –to <PIN> -name INPUT_DELAY_CHAIN <0..63>
Output Delay Element set_instance_assignment –to <PIN> -name OUTPUT_DELAY_CHAIN <0..15>
Output Enable Delay Element set_instance_assignment –to <PIN> -name OE_DELAY_CHAIN <0..15>

The Agilex™ M-series device datasheet provides information on delay chain specification and offset settings across fast and slow models. The Fast Model specifies the delay value when the maximum delay chain offset setting is selected using the fastest process. The Slow Model specifies the delay value when the maximum delay chain offset setting is selected using the slowest process within a specific speed grade.

For example, if you assign input delay chain setting to #10 using an Agilex™ M-series device with -1 speedgrade:

Minimum delay value = 10*Delay specification for Fast Model/63 = x ns

Maximum delay value = 10*Delay specification for -1V Slow Model/63 = y ns

The input delay ranges from x ns to y ns when -1 device speedgrade is selected in your design.

Note: The IOE delay chains are not process, voltage and temperature (PVT) compensated, which means the delay chain value changes across PVT.