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OCPRF100 MP Server System Technical Product Specification
Revision 1.0
64
Figure 5-5: Power Good Signal Characteristics
5.6.4 Power Supply Present Indicator (Output)
This signal is used to sense the number of power supplies in the system (operational or not). A
pin on the output connector must be allocated to pull the power supply present signal on the
power supply backplane to DC output ground. Without this pull-down, the power supply present
signal will be pulled up through a pull-up resistor to +5 V standby on the backplane. The power
supply present is an output signal from the power supply to the system.
5.6.5 Predictive Failure Signal (Output)
This signal is available on the power supply connector. A “high” state in this signal indicates that
the power supply is likely to fail in the near future due to a poorly performing fan. The predictive
fan failure signal going “high” will not cause the power supply to shut down, but it must cause the
“PRED FAIL” LED to turn on. The predictive failure is an output signal from the power supply to
the system.
† Measured relative to the power supply DC common output ground pins
.
5.6.6 Power Supply Failure Signal (Output)
This signal is available on the power supply connector. Upon receiving this signal, the system
informs the operator that the appropriate power supply has failed, and therefore, a replacement
Table 5-11: Predictive Failure Signals
Predictive Failure Signal Voltage Level † Current
LOW STATE (power supply OK) 0.4 V max 4 mA min sink current
HIGH STATE (poorly performing fan) 4 V min 0.5 mA max source current
TTL HIGH
TTL LOW
t
1
t
2
(100-1500msec) (1msec min.)
POWER
GOOD
SIGNAL
n
V
m
V
+5VDC
OUTPUT
VOLTAGE
n
V
Nominal Output Voltage +5 VDC
Minimum Output Voltage +4.75 VDC
t1 Delay Turn-on (100-1500msec)
t2 Delay Turn-off (1msec min)
Vm