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The fan outputs a SENSE signal, an open-collector output, which pulses at a rate of two
pulses per fan revolution. A baseboard pull-up resistor provides VCC to match the
baseboard-mounted fan speed monitor requirements, if applicable. Use of the SENSE
signal is optional. If the SENSE signal is not used, pin 3 of the connector should be tied
to GND.
It is recommended that a 4 pin fan header be used on the baseboard, in addition to, a
control ASIC that can send a PWM signal to the active fan heatsink solution on the 4
pin, at a nominal 25 KHz frequency. If a 3-pin CPU fan header is used instead, the
active fan heatsink solution will revert back to an automatic ambient air temperature
control mode.
The fan power header on the baseboard must be positioned to allow the fan heatsink
power cable to reach it. The fan power header identification and location must be
documented in the supplier's platform documentation, or on the baseboard itself. The
baseboard fan power header should be positioned within 177.8 mm [7 in.] from the
center of the processor socket.
Table 2-10. Fan Specifications (Boxed 4-wire PWM/DTS Heatsink Solution)
Description
+12V: 12 Volt Fan Power
Supply
IC: Fan Current Draw
SENSE: SENSE Frequency
Note:
System board should pull this pin up to V
Figure 2-26. Fan Cable Connection (Active CEK)
Table 2-11. Fan Cable Connector Pin Out (Active CEK)
2.4.8.2
Systems Considerations Associated with the Active CEK
This heatsink was designed to help pedestal chassis users to meet the processor
thermal requirements without the use of chassis ducting. It may be necessary to
implement some form of chassis air guide or air duct to meet the T
° C depending on the pedestal chassis layout. Also, while the active heatsink solution is
designed to mechanically fit into a 2U chassis, it may require additional space at the
top of the heatsink to allow sufficient airflow into the heatsink fan. Therefore, additional
48
Typ
Min
Steady
10.8
N/A
1.25
2
Pin Number
1
Ground (Constant)
2
Power (+12 V)
3
Signal: 2 pulses per revolution
4
Control 21 KHz - 28 KHz
Dual-Core Intel® Xeon® Processor 5100 Series Thermal/Mechanical Design Guide
Thermal/Mechanical Reference Design
Max
Max
Steady
Startup
12
12
13.2
1.5
1.5
2
2
2
with a resistor.
CC
Signal
Unit
Notes
V
A
Pulses per fan revolution
Color
Black
Yellow
Green
Blue
temperature of 40
LA
th
1
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