UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 53120

14.x Constraints - How can I analyze timing for a device at different temperatures? For what devices can I use the TEMPERATURE Constraint? What is the equivalent of TEMPERATURE constraint in Vivado?

Description

I want to analyze timing of my design at a different temperatures.

How canI derate the temperature using constraints and using Timing Analyzer?

For what devices is the deration possible?

What is the equivalent of the TEMPERATURE constraint in Vivado Design Suite?

Solution

1) How canI derate the temperature using constraints and using Timing Analyzer?

A) You can use the TEMPERATURE constraint in UCF to give a specific value of temperature at which the tool calculates timing. The constraint syntax is as shown below.

TEMPERATURE=value [C|F|K];

For example:

TEMPERATURE=25 C;

Additionally, you can also derate the temperature to analyze timing (by using speed files) fora specific temperature while running Timing Analysis. Check figure below. However, the deration and TEMPERATURE constraint can be used only for specific devices as given in next point.

ISE_Derate_disable.PNG
ISE_Derate_disable.PNG



2) For what devices is the deration possible?

A) The older devices, Virtex-5 and Virtex-4 FPGA, had options to use the TEMPERATURE constraint in ISE tools and to change this value in Timing Analyzer for reporting.

This option is no longer available for 6 series or 7 series devices, neither in ISE nor in Vivado design suites. Even in ISE Design Suite, this option is disabled for 6 series and 7 series devices. Note that even in the Run Timing Analysis as shown above, the Derate to option has been disabled and is fixed at 85 degrees C.

3) What is the equivalent of TEMPERATURE constraint in Vivado Design Suite?

A) Vivado DesignSuitedoes not have an equivalent command for TEMPERATURE constraint, because, starting from 6 series devices, the TEMPERATURE constraint does not affect the design. Since Vivado toolsonly support 7 series devices, there is no need of an equivalent TEMPERATURE constraint.

AR# 53120
Date Created 11/28/2012
Last Updated 11/28/2012
Status Active
Type General Article
Devices
  • Virtex-7
Tools
  • Vivado - 2012.2
  • ISE Design Suite - 14