FPGA Hold Time Slack

Description

FPGA Hold Time Slack: Compute simplified hold slack as minimum clock-to-output plus minimum data-path delay minus hold time and adverse skew. Positive slack meets this model; use actual launch/capture clock paths for sign-off.

When to use FPGA Hold Time Slack

Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Clock-to-output min (ns): Required number input.
Path delay min (ns): Required number input.
Hold time (ns): Required number input.
Adverse skew (ns): Required number input.

How FPGA Hold Time Slack works

Compute simplified hold slack as minimum clock-to-output plus minimum data-path delay minus hold time and adverse skew. Positive slack meets this model; use actual launch/capture clock paths for sign-off. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Hold Slack ns: The resulting hold slack ns returned as a number.

Limitations and assumptions

Setup, hold, jitter, and eye estimates require a consistent timing reference and sign convention. Clock uncertainty, skew, data-dependent jitter, process-voltage-temperature corners, routing, crosstalk, and statistical margins must come from the implementation and interface specification.
Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Alternative or Complementary approaches

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

References

Timing closure — Wikipedia contributors

Similar or alternative tools

FPGA Setup Time Slack
Compute worst-case setup slack as period−clock-to-output−maximum path delay−setup−adverse skew−jitter. Positive slack meets this simplified single-cycle timing constraint.
FPGA Clock Jitter Allowance
Calculate remaining setup-time budget for combined clock jitter after clock period, clock-to-output, combinational path delay, setup time, and skew. Use worst-case values in the same time unit.
SPI Frequency from Trace Delay
Estimate a conservative SPI clock ceiling from trace length, propagation delay per metre, and available timing fraction of a cycle. This only budgets propagation delay; include device clock-to-output, setup, skew, and return path in a real design.