BeginnerQuestion 23 of 40Source PDF page 23

What is an SDC file, and what are 'basic timing constraints'?

From PDVerse STA Mentor Guide · pdVerse Mentor Guide

Short Answer

SDC stands for Synopsys Design Constraints, and it is the industry-standard Tcl-based text format used to write down a design's timing intent for the STA tool to read.

Example

Inside an SDC file you describe things like clock definitions, the timing of inputs and outputs at the chip boundary, timing exceptions, and environmental conditions the design must be checked under.

Why It Matters

An STA tool cannot guess what your design is supposed to do; it can only trace paths and compare numbers. The SDC file is how you tell the tool what a clock cycle is, where clocks come from, and what counts as a valid check, so the whole analysis has something meaningful to measure against.

Mentor Note — Common Mistake

Don't treat the SDC as an afterthought you write quickly at the end. A weak or incomplete SDC leads directly to under-constrained checks, and a green report_timing on an under-constrained design is meaningless.

Visual explanationSTA context: What is an SDC file, and what are 'basic timing constraints'?
STA context: What is an SDC file, and what are 'basic timing constraints'?A three-step concept map summarizes the focus, core answer, and practical verification for What is an SDC file, and what are 'basic timing constraints'?Question focusWhat is an SDC file, andwhat are 'basic timingconstraints'?Core answerSDC stands for SynopsysDesign Constraints, andit is theindustry-standard…Verify in practiceConfirm the path,constraints, clockassumptions, and timingreport.Understand → explain the mechanism → verify the assumptions

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