Technical data

7-12
Power Supplies
7
Load Sharing
The 12- and 20-slot chassis are capable of providing load sharing
functions amongst the power supplies. With load sharing, each
power supply provides part of the load requirements for the
system. If one power supply fails in such a configuration, the other
will assume the entire load.
For the load-sharing capabilities of the system to function properly,
the following three criteria must be met:
1. Each power supply must independently supply a minimum
of 5 Amps at 5 Volts.
2. The system must supply a minimum of 12 Amps. In this case,
each power supply will contribute 50% +/- 10%.
3. Power must be AC/AC or DC/DC (not AC/DC).
Power Supply Enable
The power supply enable is a system controlled signal that allows the supply to output
DC power. The signal sense is LOW = no output, HIGH = DC output. This signal line
from the power supply may float up to 15 volts when not connected. This line does not
output more than 10 ma when externally connected to ground. The power supply must
remain off if this signal is less than 0.6 volts.
Holdover Storage
Output voltage stays within regulation limits for at least 20 mS from the last peak of the
line voltage cycle after input power is removed. Measured with 36Vdc input and 700
watts of output power.
OverVoltage Protection
+5 volt output shall limit voltage at 6.3 Vdc +/- 3% under any single fault condition.
+12 volt outputs shall not exceed +15.0 Vdc under any single fault condition. Power
supply latches off and cycling the AC power restarts.
Overtemperature Protection
The power supply shuts down when the internal temperature exceeds maximum safe
rating. Power supply latches off and cycling enable restarts.
Table 7-4. 700 Watt DC Power Supply Specifications (Continued)