Fujifilm Xeon 5050 S26361-F3248-L300 Datenbogen

Dual-Core Intel® Xeon® Processor 5000 Series Datasheet

79

Tcontrol is a temperature specification based on a temperature reading from the 
thermal diode. The value for Tcontrol will be calibrated in manufacturing and configured 
for each processor. The Tcontrol value is set identically for both processor cores. The 
Tcontrol temperature for a given processor can be obtained by reading the 
IA32_TEMPERATURE_TARGET MSR in the processor. The Tcontrol value that is read 
from the IA32_TEMPERATURE_TARGET MSR must be converted from Hexadecimal to 
Decimal and added to a base value of 60

°

C. The value of Tcontrol may vary from 0x00h 

to 0x1Eh. 

When Tdiode is above Tcontrol, then T

CASE

 must be at or below T

CASE_MAX

 as defined by 

the thermal profile. (Refer to 

, 

 ; 

, 

). Otherwise, the processor temperature 

can be maintained at or below Tcontrol.

The Dual-Core Intel Xeon Processor 5000 series incorporates an on-die PNP transistor 
whose base emitter junction is used as a thermal “diode”, one per core, with its 
collector shorted to Ground. A thermal sensor located on the system board may 
monitor the die temperature of the processor for thermal management and fan speed 
control. 

, 

 and 

 provide the “diode” parameters and 

interface specifications. Two different sets of “diode” parameters are listed in 

 

and 

. The Diode Model parameters (

) apply to traditional thermal 

sensors that use the Diode Equation to determine the processor temperature. 
Transistor Model parameters (

) have been added to support thermal sensors 

that use the transistor equation method. The Transistor Model may provide more 
accurate temperature measurements when the diode ideality factor is closer to the 
maximum or minimum limits. This thermal “diode” is separate from the Thermal 
Monitor’s thermal sensor and cannot be used to predict the behavior of the Thermal 
Monitor. 

When calculating a temperature based on thermal diode measurements, a number of 
parameters must be either measured or assumed. Most devices measure the diode 
ideality and assume a series resistance and ideality trim value, although some are 
capable of also measuring the series resistance. Calculating the temperature is then 
accomplished by using the equations listed under 

. In most temperature 

sensing devices, an expected value for the diode ideality is designed-in to the 
temperature calculation equation. If the designer of the temperature sensing device 
assumes a perfect diode, the ideality value (also called n

trim

) will be 1.000. Given that 

most diodes are not perfect, the designers usually select an n

trim 

value that more 

closely matches the behavior of the diodes in the processor. If the processors diode 
ideality deviates from that of n

trim

, each calculated temperature will be offset by a fixed 

amount. The temperature offset can be calculated with the equation: 

T

error(nf)

 = T

measured

 X (1- n

actual

/n

trim 

) 

where T

error(nf) 

is the offset in degrees C, T

measured 

is in Kelvin, n

actual 

is the measured 

ideality of the diode, and n

trim 

is the diode ideality assumed by the temperature sensing 

device. 

In order to improve the accuracy of diode based temperature measurements, a new 
register (Tdiode_Offset) has been added to Dual-Core Intel Xeon Processor 5000 series 
which will contain thermal diode characterization data. During manufacturing each 
processor’s thermal diode will be evaluated for its behavior relative to a theoretical 
diode. Using the equation above, the temperature error created by the difference