Datasheet

T
CF
=
(80 + 273) = -1.75
o
C
˜
1.003 - 1.008
1.003
¹
·
©
§
T
CF
=
(T
CR
+ 273K)
x
K
S
- K
PROCESSOR
K
S
¹
·
©
§
LM95214
www.ti.com SNIS146A –MARCH 2007–REVISED MARCH 2013
Processor Family Diode Equation η
D
, non-ideality Series R,Ω
min typ max
Pentium™ III CPUID 67h 1 1.0065 1.0125
Pentium III CPUID 68h/PGA370Socket/
1.0057 1.008 1.0125
Celeron
Pentium 4, 423 pin 0.9933 1.0045 1.0368
Pentium 4, 478 pin 0.9933 1.0045 1.0368
Pentium 4 on 0.13 micron process, 2 - 3.06
1.0011 1.0021 1.0030 3.64
GHz
Pentium 4 on 90 nm process 1.0083 1.011 1.023 3.33
Intel Processor on 65 nm process 1.000 1.009 1.050 4.52
Pentium M (Centrino) 1.00151 1.00220 1.00289 3.06
MMBT3904 1.003
AMD Athlon MP model 6 1.002 1.008 1.016
AMD Athlon 64 1.008 1.008 1.096
AMD Opteron 1.008 1.008 1.096
AMD Sempron 1.00261 0.93
Compensating for Different Non-Ideality
In order to compensate for the errors introduced by non-ideality, the temperature sensor is calibrated for a
particular processor. Texas Instruments temperature sensors are always calibrated to the typical non-ideality and
series resistance of a given transistor type. The LM95214 is calibrated for the non-ideality factor and series
resistance values of the MMBT3904 transistor without the requirement for additional trims. When a temperature
sensor calibrated for a particular thermal diode type is used with a different thermal diode type, additional errors
are introduced.
Temperature errors associated with non-ideality of different processor types may be reduced in a specific
temperature range of concern through use of software calibration. Typical Non-ideality specification differences
cause a gain variation of the transfer function, therefore the center of the temperature range of interest should be
the target temperature for calibration purposes. The following equation can be used to calculate the temperature
correction factor (T
CF
) required to compensate for a target non-ideality differing from that supported by the
LM95214.
where
• η
S
= LM95214 non-ideality for accuracy specification
• η
PROCESSOR
= Processor thermal diode typical non-ideality
• T
CR
= center of the temperature range of interest in °C (7)
where
The correction factor should be directly added to the temperature reading produced by the LM95214. For
example when using the LM95214, with the 3904 mode selected, to measure a AMD Athlon processor, with a
typical non-ideality of 1.008, for a temperature range of 60 °C to 100 °C the correction factor would calculate to:
(8)
Therefore, 1.75°C should be subtracted from the temperature readings of the LM95214 to compensate for the
differing typical non-ideality target.
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