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.