Cpu Thermal Trip Points; Table 16: Cpu Thermal Trip Points - VersaLogic Hawk Reference Manual

The decision as to which thermal solution to use can be based on several factors including:

Number of CPU cores in the SoC (single, dual, or quad)

CPU and video processing utilization by the user application

Temperature range within which the EPU-3310 will be operated

Air movement (or lack of air movement)
Most of these factors involve the demands of the user application on the EPU-3310 and cannot
be isolated from the overall thermal performance. Due to the interaction of the user application,
the Hawk thermal solution, and the overall environment of the end system, thermal performance
cannot be rigidly defined.
The ambient air surrounding the EPU-3310 needs to be maintained at 85 ºC or below. This would
include the space between the two main boards as well as the space beneath an installed
miniPCIe expansion board. This may prove to be challenging depending on how and where the
EPU-3310 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 EPU-3310 Thermal Characterization, beginning
on page 45) within the enclosure

Position the EPU-3310 board to allow for convective airflow

Lower the system level temperature requirement as needed

CPU Thermal Trip Points

The CPU cores in the Hawk have their own thermal sensors. Coupled with these sensors are
specific reactions to three thermal trip points. Table 16 describes the three thermal trip points.
Note that these are internal temperatures that are about 10 ºC above the heat plate temperature.
Trip Point
Passive (Note 1)
Critical (Note 2)
Maximum core temperature
Notes:
1. The default value in the BIOS Setup program for this trip point is 90 ºC.
2. The default value in the BIOS Setup program for this trip point is 100 ºC.
These trip points allow maximum CPU operational performance while maintaining the lowest
CPU temperature possible. The long-term reliability of any electronic component is degraded
when it is continually run near its maximum thermal limit. Ideally, the CPU core temperatures
will be kept well below 100 ºC with only brief excursions above.
VL-EPU-3310 Reference Manual

Table 16: CPU Thermal Trip Points

At this temperature, the CPU cores throttle back to a lower speed. This
reduces the power draw and heat dissipation, but lowers the processing
speed.
At this temperature, the operating system typically puts the board into a
sleep or other low-power state.
The CPU turns itself off when this temperature is reached. This is a fixed
trip point and cannot be adjusted.
Thermal Considerations
Description
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