Thermal Considerations
EBX-38 Hardware Reference Manual
61
S
YSTEM
-
LEVEL
C
ONSIDERATIONS
The EBX-38 thermal solutions – either the HDW-406 heat sink alone or with the HDW-407 fan –
are part of the larger thermal system of the application. Other PC/104 boards stacked above the
Viper and any other nearby heat sources (power supplies or other circuits), all contribute to how
the EBX-38 will perform from a thermal standpoint.
The ambient air surrounding the EBX-38 needs to be maintained at 85 ºC or below. This can
prove to be challenging depending on how and where the EBX-38 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 beginning on page 64) within the enclosure
Position the EBX-38 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 EBX-38 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 EBX-38 and cannot be
isolated from the overall thermal performance. Due to the interaction of the user application, the
Viper thermal solution, and the overall environment of the end system, thermal performance
cannot be rigidly defined.
CPU
T
HERMAL
T
RIP
P
OINTS
The CPU cores in the Viper have their own thermal sensors. Coupled with these sensors are
specific reactions to four thermal trip points. The table below describes the four thermal trip
points.
