Intel SR6850HW4 User Manual
Page 73
Intel® Server Platform SR6850HW4 TPS
Power Supply
Revision 1.0
Intel order number D23151-001
61
5.4.9 Fan Speed Control
The power supply provides forced air-cooling through three DC fans that have intake through
the circular grill. The cooling fans are 60mm in diameter and 38mm in depth. The fans are
mounted to the front (output connector), and exhaust through the rear (AC Inlet connector) of
the PS case.
The power supply uses a fan speed controller that is based on the input Fan_Cntl. The input is
an analog signal from 0.0V to 3.0V. Control of the fan is linear in relation to the Fan_Cntl signal.
Table 38. Power Supply Fan Voltage
Fan_Cntl Voltage
Minimum Fan Voltage
Maximum Fan Voltage
0.00V 7.00V
7.50V
1.50V 9.55V
10.05V
3.00V 11.50V
12.60V
A fan fault is defined as a fan RPM below 1,000 ±200 RPM during normal operation. This fault is
inhibited for 15 ±5 seconds when the power supply outputs are first powered on. This allows
time for the fan to come up to speed and the fan detects circuitry to stabilize.
A fault on two fans turns off the power supply. See Section 5.2.
Note:
Fan speed control must operate even if no AC is applied to the power supply. Fan power
comes from the 12V bus after the OR’ing diode. The control circuit power comes from either the
12V bus and/or the 3.3V
stby
bus.
5.4.10
Power Supply Module LED indicators
There are three LEDs on the rear of the power supply, next to the AC input power connector.
5.4.10.1
Power Supply Fail
The amber power supply fail LED is driven by internal circuitry. It lights when a power rail has
failed. The LED is not lit if the supply turns off due to PS_KILL. The LED illuminates even if the
power supply is in a latched state. The only time during a fault when it does not illuminate is if
the +3.3V
stby
is lost.
5.4.10.2 Power
Good
The green power good LED is driven by internal circuitry. It lights whenever PWRGD is
asserted.
5.4.10.3 AC
OK
The green AC OK LED is driven by internal circuitry. It lights whenever VIN_GOOD is asserted.