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25175H—March 2003
Appendix A - Thermal Diode Calculations
Preliminary Information
The formulas in Equation (3) and Equation (4) can be used to
calculate the temperature offset for temperature sensors that
do not employ series resistance cancellation. The result is
added to the value measured by the temperature sensor.
Contact the vendor of the temperature sensor being used for
the value of n
. Refer to the document, On-Die Thermal Diode
f,TS
Characterization, order# 25443, for further details.
Equation (3) shows the equation for calculating the lumped
ideality factor (n
f, lumped
resistance cancellation.
n
n
--------------------------------------------------------------------- -
=
+
,
,
f lumped
f actual
k
(
-- - T
q
Equation (4) shows the equation for calculating temperature
offset (T
) in sensors that do not employ series resistance
offset
cancellation.
(
T
T
273.15
=
+
,
die spec
o f f s e t
Equation (5) is the temperature offset for temperature sensors
that utilize series resistance cancellation. Add the result to the
value measured by the temperature sensor. Note that the value
of n
in Equation (5) may not equal the value used in
f,TS
Equation (4).
(
T
T
273.15
=
+
,
die spec
o f f s e t
AMD Athlon™ XP Processor Model 8 Data Sheet
) in sensors that do not employ series
⋅
(
)
R
I
I
–
T
high
low
I
)
⋅
------- -
273.15
ln
high
+
,
die spec
I
low
n
)
⋅
1
-------------- -
,
f lumped
–
n
,
f TS
n
)
⋅
actual
1
-------------- -
,
f
–
n
,
f TS
(3)
(4)
(5)
85
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