Intel® Server System R2000WF Product Family Technical Product Specification
50
Table 32. Example load share threshold for activating supplies
State
Enable Threshold for
VCR_ON_EN
Disable Threshold for
VCR_ON_DIS
CR_BUS
De-Asserted/
Asserted States
Standard Redundancy
NA; Ignore dc/dc_ active# signal; power supply is always ON
OK = High, Fault = Low
Cold Redundant Active
NA; Ignore dc/dc_ active# signal; power supply is always ON
OK = High, Fault = Low
Cold Standby 1 (
02h
)
3.2 V (40% of max)
3.2 V x 0.5 x 0.9 = 1.44 V
OK = Open, Fault = Low
Cold Standby 2 (
03h
)
5.0 V (62% of max)
5.0 V x 0.67 x 0.9 = 3.01 V
OK = Open, Fault = Low
Cold Standby 3 (
04h
)
6.7 V (84% of max)
6.7 V x 0.75 x 0.9 = 4.52 V
OK = Open, Fault = Low
Note
: Maximum load share voltage is 8.0 V at 100% of rated output power.
Note
: Load share bus thresholds are examples. For a given power supply, these will be customized to
maintain the best efficiency curve for that specific model.
3.5.2
Powering on Cold Standby Supplies during a Fault or Over Current Condition
When an active power supply asserts its
CR_BUS
signal (pulling it low), all parallel power supplies in cold
standby mode will power on within 100 μsec.
3.5.3
BMC Requirements
The BMC uses the
Cold_Redundancy_Config
command to define and configure the power supply’s role
in cold redundancy and to turn on/off cold redundancy.
To allow for equal loading over the life time of installed power supplies, the BMC shall schedule a rolling re-
configuration of installed power supplies so that each alternates between being the “Active” power supply
and the “Cold Stby” power supply.
Events that trigger a re-configuration of the power supplies using the
Cold_Redundancy_Config
command are listed below.
AC power ON
PSON power ON
Power supply failure
Power supply inserted into system
3.5.4
Power Supply Turn on Function
Powering on and off of the cold standby power supplies is only controlled by each PSU sensing the Vshare
bus. Once a power supply turns on after crossing the enable threshold, it lowers itself to the disable
threshold. The system defines the position of each power supply in the cold redundant operation. It does
this each time the system is powered on, a power supply fails, or a power supply is added to the system.
The system is relied upon to tell each power supply where it resides in the cold redundancy scheme.
3.6
Closed Loop System Throttling (CLST)
The server system has support for Closed Loop System Throttling (CLST) which prevents the system from
crashing if a power supply module is overloaded or over heats. Should system power reach a pre-
programmed power limit, CLST throttles system memory and/or processors to reduce power. System
performance is impacted should this occur.
