Datasheet

Thermal Specifications and Design Considerations
88 Datasheet
5.2.5 THERMTRIP# Signal
Regardless of whether or not Thermal Monitor is enabled, in the event of a catastrophic
cooling failure, the processor will automatically shut down when the silicon has reached
an elevated temperature (refer to the THERMTRIP# definition in Table 25). At this
point, the FSB signal THERMTRIP# will go active and stay active as described in
Table 25. THERMTRIP# activation is independent of processor activity and does not
generate any bus cycles.
5.2.6 T
CONTROL
and Fan Speed Reduction
T
CONTROL
is a temperature specification based on a temperature reading from the
thermal diode. The value for T
CONTROL
will be calibrated in manufacturing and
configured for each processor. When T
DIODE
is above T
CONTROL
then T
C
must be at or
below T
C-MAX
as defined by the thermal profile in Table 27 and Figure 13; otherwise,
the processor temperature can be maintained at T
CONTROL
(or lower) as measured by
the thermal diode.
The purpose of this feature is to support acoustic optimization through fan speed
control. Contact your Intel representative for further details and documentation.
5.2.7 Thermal Diode
The processor incorporates an on-die PNP transistor whose 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. Table 29,Table 30, Table 31 and Table 32
provide the "diode" parameter and interface specifications. Two different sets of "diode"
parameters are listed in Table 29 and 30. The Diode Model parameters (Table 29) apply
to traditional thermal sensors that use the Diode Equation to determine the processor
temperature. Transistor Model parameters (Table 30) 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.
NOTES:
1. Intel does not support or recommend operation of the thermal diode under reverse bias.
2. Characterized across a 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:
I
FW
= I
S
* (e
qV
D
/nkT
–1)
where I
S
= saturation current, q = electronic charge, V
D
= voltage across the diode, k = Boltzmann
Constant, and T = absolute temperature (Kelvin).
Table 29. Thermal “Diode” Parameters using Diode Model
Symbol Parameter Min Typ Max Unit Notes
I
FW
Forward Bias Current 5 — 200 µA 1
n Diode Ideality Factor 1.000 1.009 1.050 — 2, 3, 4
R
T
Series Resistance 2.79 4.52 6.24 Ω 2, 3, 5