Specifications

QSSC-S4R Technical Product Specification 850W Power Supply
107
12.4.4 Short Circuit Protection
A short circuit, which is defined as an impedance of 0.1 ohms or less, applied to any output during start-up or while
running will not cause any damage to the power supply (connectors, components, PCB traces, etcetera). TBC
When the +3.3VSB is shorted the output may go into “hiccup mode.” When the +3.3VSB attempts to restart, the
maximum peak current from the output must be less than 8.0A. The maximum average current, taking into account the
“hiccup” duty cycle, must be less than 4.0A.
12.4.5 Over Temperature Protection
The power supply will be protected against over temperature conditions caused by loss of fan cooling or excessive
ambient temperature. In an OTP condition the PSU will shutdown. When the power supply temperature drops to within
specified limits, the power supply shall restore power automatically, while the 3.3Vsb remains always on. The OTP
circuit must have built in margin such that the power supply will not oscillate on and off due to temperature recovering
condition. The OTP trip level shall have a minimum of 4°C of ambient temperature margin.
12.4.6 Reset After Shutdown
If the power supply latches into a shutdown state due to a fault condition on any output, the power supply will return to
normal operation only after the fault has been removed and the power supply has been power-cycled. Power cycling is
defined as either:
x Removing AC input power, waiting for +3.3V standby to drop below 1.0V, then reapplying AC power. (The time it
takes for +3.3V standby to drop below 1.0V must not exceed 15 seconds.)
x Cycling the state of PS_ON from on to off to on. (The minimum cycle time will be 1mS.)
12.4.7 Current Sharing
Outputs of two (or more) supplies connected in parallel must meet the regulation requirements of a single supply.
Under normal operation with two (or more) supplies running in parallel the following outputs must share load current.
Table 49. Output Current Sharing
Output Level Output Sharing
+3.3V standby Not required
+12V Active
The voltage of this signal will be a linear slope from zero loads to full load. At 65.4A, the output of a single power
supply must be between 4V to 4.20V. At 130.8A, the output when two power supplies are running in parallel must be
between 4V to 4.30V. Current sharing requirements are described in the table below:
Table 50. +12V Current Sharing Requirements
Sharing
requirements:
(Voltage will be
linear from zero to
full load)
Total Load I share Min I share Max # of supplies
100% 4.00 4.30 2
100% 7.75 8.25 1
50% 4.00 4.20 1
0% 0.00 0.50 1
12.4.8 I2C Devices
All I2C devices will be powered from the cathode side of the +3.3V standby OR’ing diode. This will allow the status and
FRU data to be read from a power supply that is not powered on or has some other fault. Protection is provided so if a
fault within the power supply occurs it does not take down the +3.3V standby bus.
Address locations will be determined by external settings through P1, pin A5. The A1 and A2 address will be wired high
on the power supply. (NE1617A* does not have an A2 address). The alert signal from (only) the I/O port will be through
P1, pin D5.
12.4.9 Module Cold Redundancy Operation
The power supply module supports both hot-redundant (when all supplies being active all the time) and cold-redundant
operation (when only one, two, or three supplies are active providing all power to the system while the remaining
supply is put into a standby state) via a cold redundancy (CR) control circuit.