Thermal Considerations
VL-EPU-3311 Reference Manual
58
Thermal Specifications, Restrictions, and Conditions
Graphical test data is in the section titled EPU-3311 Thermal Characterization, beginning on
page 59. Refer to that section for the details behind these specifications. These specifications
are the thermal limits for using the EPU-3311 with one of the defined thermal solutions.
Due to the unknown nature of the entire thermal system, or the performance requirement of the
application, VersaLogic cannot recommend a particular thermal solution. This information is
intended to provide guidance in the design of an overall thermal system solution.
Table 18: Absolute Minimum and Maximum Air Temperatures
Board
With Heat Plate
With Heat Sink
(HDW-406)
With Heat Sink + Fan
(HDW-406 + HDW-411)
VL-EPU-3311-EAP
-40 ° to +85 °C
-40 ° to +85 °C
-40 ° to +85 °C
VL-EPU-3311-EBP
-40 ° to +85 °C
-40 ° to +85 °C
-40 ° to +85 °C
VL-EPU-3311-EDP
-40 ° to +85 °C
-40 ° to +85 °C
-40 ° to +85 °C
Overall Restrictions and Conditions:
Ranges shown assume less than 90% CPU utilization.
Keep the maximum CPU core temperature below 100ºC.
The ambient air surrounding the EPU-3311 needs to be maintained at 85 ºC or below. This
includes the space between the two main boards as well as the space beneath an installed
Mini PCIe expansion board. A recommended overall air flow of 100 linear feet per minute
(LFM) / 0.5 linear meters per second (LMS) addresses this requirement. If this air flow is
not provided, other means must be implemented to keep the adjacent air at 85 ºC or below.
Heat Plate Only Restrictions and Conditions:
The heat plate must be kept below 90 °C. This applies to a heat plate mounted directly to
another surface as well as when the HDW-408 heat pipe block is used.
Heat Sink Only Considerations:
At 85°C air temperature and 90% CPU utilization, there will be little if any thermal margin
to a CPU core temperature of 100 °C or the passive trip point (see test data). If this is the use
case, consider adding a fan or other additional air flow.
Heat Sink with Fan Considerations:
The heat sink and fan combination cools the CPU when it is running in high temperature
environments, or when the application software is heavily utilizing the CPU or video
circuitry. The fan assists in cooling the heat sink and provides additional air movement
within the system.
Integrator’s Note:
The ambient air surrounding the EPU-3311 needs to be maintained
at 85 °C or below.
