External Thermal Regulation - Kontron CP308 User Manual

CP308 Thermal Considerations
6.4

External Thermal Regulation

To ensure the best possible basis for operational stability and long-term reliability, the CP308
is equipped with a heat sink. Coupled together with system chassis, which provides variable
configurations for forced airflow, controlled active thermal energy dissipation is guaranteed.
The physical size, shape, and construction of the heat sink ensures the lowest possible thermal
resistance. In addition, the CP308 has been specifically designed to efficiently support forced
airflow as found in modern CompactPCI systems.
Thermal Characteristic Graphs
The thermal characteristic graphs shown on the following sections illustrate the maximum am-
bient air temperature as a function of the volumetric airflow rate for the power consumption in-
dicated. The diagrams are intended to serve as guidance for reconciling board and system with
the required computing power considering the thermal aspect. One diagram per CPU version
is provided. There are up to two curves representing upper level working points based on dif-
ferent levels of average CPU utilization. When operating below the corresponding curve, the
CPU runs steadily without any intervention of thermal supervision. When operated above the
corresponding curve, various thermal protection mechanisms may take effect resulting in tem-
porarily reduced CPU performance or finally in an emergency stop in order to protect the CPU
and the chipset from thermal destruction. In real applications this means that the board can be
operated temporarily at a higher ambient temperature or at a reduced flow rate and still provide
some margin for temporarily requested peak performance before thermal protection will be ac-
tivated.
An airflow of 2.0 m/s is a typical value for a standard Kontron ASM rack (3U CompactPCI rack
with a 1U cooling fan tray). For other racks or housings the available airflow will differ. The
maximum ambient operating temperature must be recalculated and/or measured for such
environments. For the calculation of the maximum ambient operating temperature, the
processor and chipset junction temperature must never exceed the specified limit for the
involved processor and chipset.
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