User guide
User Guide CC3-CAJUN • Low Power CompactPCI CPU
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EKF Elektronik GmbH • Philipp-Reis-Str. 4 • 59065 Hamm • Germany
Tel. +49 (0)2381/6890-0 • Fax. +49 (0)2381/6890-90 • info@ekf.de • www.ekf.com
The forced airflow thermal resistance of the snap-on heatsink is 4.6K/W @ 200lfm, 2.7K/W @
400lfm and 2.0K/W @ 600lfm. With no forced airflow (natural convection) the heat sink
thermal resistance is ~13.8K/W. With 100°C as maximum specified die temperature, the worst
case ambient temperatures for the CC3-CAJUN can be calculated a follows:
Maximum Permissible Ambient Temperature
Processor Max. Power 0 LFM 200 LFM 400 LFM 600 LFM
ULV Celeron
400MHz
4.23W 41.5°C
80.5°C 88.5°C 91.5°C
ULV Celeron
650MHz
8.3W - 61.5°C
77.5°C 83.0°C
LV Pentium
III 800MHz
11.2W - 48.0°C 69.5°C
77.5°C
LV Pentium
III 933MHz
12.2W - 43.5°C 67.0°C
75.0°C
Temperatures marked italic/grey:
Nominal values only, the board should not be operated permanently beyond 70°C
As it can be seen, natural convection cooling is an option for the CC3-1-CAJUN only, which is
equipped with the ULV Celeron 400MHz processor. Forced airflow cooling between 200lfm
(ULV Celeron) and 400lfm (LV Pentium III) is recommended for typical operation of the board.
A special method to reduce power consumption and therefore increasing the maximum ambient
temperature, is to force the processor into the 'Throttle Mode'. This is achieved by actuating the
'Stop Clock' input of the CPU, and can be activated through the BIOS settings. A Throttle Mode
of 50% e.g. means a duty cycle of 50% on the stop clock input. However, while saving a certain
amount in power consumption, the data throughput of the processor is also reduced.