Thermal Considerations
39
Lion (VL-EPMe-42) Reference Manual
System-level Considerations
The EPMe-42 thermal solutions – either the HDW-406 heat sink alone or with the HDW-413 fan –
are part of the larger thermal system of the application. Other PC/104 boards stacked under the
Lion and any other nearby heat sources (power supplies or other circuits), all contribute to how the
EPMe-42 will perform from a thermal standpoint.
The ambient air surrounding the EPMe-42 needs to be maintained at 85ºC or below. This can
prove to be challenging depending on how and where the EPMe-42 is mounted in the end user
system. Standard methods for addressing this requirement include the following:
Provide a typical airflow of 100 linear feet per minute (LFM) / 0.5 linear meters per second
(as described in the section titled EPMe-42 Thermal Characterization, beginning on page
42) within the enclosure
Position the EPMe-42 board to allow for convective airflow
Lower the system level temperature requirement as needed
The decision as to which thermal solution to use can be based on several factors including (but
not limited to) the following:
Number of CPU cores in the SoC (single, dual, or quad)
CPU core program utilization
Temperature range within which the EPMe-42 will be operated
Air movement (or lack of air movement)
Video processing intensity
Memory access demands
High speed I/O usage (PCIe, USB 3.0, SATA usage)
Most of these factors involve the demands of the user application on the EPMe-42 and cannot be
isolated from the overall thermal performance. Due to the interaction of the user application, the
Lion thermal solution, and the overall environment of the end system, thermal performance cannot
be rigidly defined.
