Thermal Settings - 2023.2 English

Power Design Manager User Guide (UG1556)

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2023.2 English

Leakage power increases exponentially with respect to junction temperature. Thus, it is very important to accurately specify the environment conditions in PDM. The environment settings allow the following flows:

User Specified Junction Temperature
Enter the targeted junction temperature or the maximum junction temperature of the device and ambient temperature.
  • PDM assumes the default value of Effective ΘJA as 0 (the Effective ΘJA field is read-only).
PDM Estimated Junction Temperature
Enter ambient temperature and Effective ΘJA, from which PDM calculates the junction temperature.
  • Derive Effective ΘJA from thermal simulation.
Note: PDM uses the thermal settings only to calculate the junction temperature based on the following formula:

Junction Temperature = Ambient Temperature + (Effective ΘJA * Total On-chip Power)

Important: PDM does not perform thermal analysis to calculate the effective ΘJA. It reports the requirements based on given junction temperature and ambient temperature values. AMD suggests that you replace the PDM populated maximum Effective ΘJA with the determined Effective ΘJA from thermal analysis of the system, preferably from thermal simulation or actual system measurement.

PDM alerts you if the specified or calculated junction temperature exceeds the device temperature grade margin.

Figure 1. Thermal Settings in PDM

Note: AMD provides thermal models for Siemens Flotherm , Ansys IcePak and tool agnostic ECXML format. AMD recommends you to perform a system-level thermal simulation. This allows you to effectively assess the conditions and use the Effective ΘJA parameter from simulation to estimate accurate device junction temperature in PDM.