Thermal Diode; Thermal "Diode" Parameters Using Diode Model - Intel CORE 2 DUO E4000 - DATASHEET 3-2008 Datasheet

5.3

Thermal Diode

The processor incorporates an on-die PNP transistor where the base emitter junction is
used as a thermal "diode", 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.
the "diode" parameter and interface specifications. Two different sets of "diode"
parameters are listed in
apply to traditional thermal sensors that use the Diode Equation to determine the
processor temperature. Transistor Model parameters
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.
T
CONTROL
thermal diode. The value for T
configured for each processor. When T
below T
C_MAX
temperature can be maintained at T
diode.
Table 32.

Thermal "Diode" Parameters using Diode Model

Symbol
I
FW
n
R
T
NOTES:
1. Intel does not support or recommend operation of the thermal diode under reverse bias.
2. Characterized across a temperature range of 50 – 80 °C.
3. Not 100% tested. Specified by design characterization.
4. The ideality factor, n, represents the deviation from ideal diode behavior as exemplified by
the diode equation:
where I
k = Boltzmann Constant, and T = absolute temperature (Kelvin).
5. The series resistance, R
junction temperature. R
include any socket resistance or board trace resistance between the socket and the
external remote diode thermal sensor. R
with automatic series resistance cancellation to calibrate out this error term. Another
application is that a temperature offset can be manually calculated and programmed into
an offset register in the remote diode thermal sensors as exemplified by the equation:
where T
Constant, q = electronic charge.
88
Table 32
is a temperature specification based on a temperature reading from the
CONTROL
as defined by the thermal profile in
Parameter
Forward Bias Current
Diode Ideality Factor
Series Resistance
I
FW
= saturation current, q = electronic charge, V
S
, is provided to allow for a more accurate measurement of the
T
, as defined, includes the lands of the processor but does not
T
T
= sensor temperature error, N = sensor current ratio, k = Boltzmann
error
Thermal Specifications and Design Considerations
Table 32,Table
and Table 33. The Diode Model parameters
(Table
will be calibrated in manufacturing and
is above T
DIODE CONTROL
Table
(or lower) as measured by the thermal
CONTROL
Min Typ
5 —
1.000 1.009
2.79 4.52
= I * (e qV /nkT –1)
D
S
D
can be used by remote diode thermal sensors
T
= [R * (N–1) * I
error T FWmin
33, and Table 34 provide
(Table
33) have been added to
, then T must be at or
C
28; otherwise, the processor
Max Unit
200 µA
1.050 -
6.24 Ω
= voltage across the diode,
] / [nk/q * ln N]
32)
Notes
1
2, 3, 4
2, 3, 5
Datasheet