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Table 20.
Thermal Diode Parameters using Transistor Model
Symbol
I
FW
I
E
n
Q
Beta
R
T
NOTES:
1.
Intel does not support or recommend operation of the thermal diode under reverse bias.
2.
Same as I
3.
Characterized across a temperature range of 50-100°C.
4.
Not 100% tested. Specified by design characterization.
5.
The ideality factor, n
by the equation for the collector current:
I
=I
C
where I
base emitter junction (same nodes as VD), k = Boltzmann Constant, and T = absolute
temperature (Kelvin).
6.
The series resistance, R
more accurate readings as needed.
When calculating a temperature based on the 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 are capable of
also measuring the series resistance. Calculating the temperature is then accomplished
using the equations listed under
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
usually select an n
the processor. If the processor diode ideality deviates from that of the n
calculated temperature is offset by a fixed amount. This temperature offset can be
calculated with the equation:
Where T
error(nf)
ideality of the diode, and n
sensing device.
5.2
Intel® Thermal Monitor
The Intel Thermal Monitor helps control the processor temperature by activating the
TCC (Thermal Control Circuit) when the processor silicon reaches its maximum
operating temperature. The temperature at which the Intel Thermal Monitor activates
the TCC is not user configurable. Bus traffic is snooped in the normal manner and
interrupt requests are latched (and serviced during the time that the clocks are on)
while the TCC is active.
With a properly designed and characterized thermal solution, it is anticipated that the
TCC would only be activated for very short periods of time when running the most
power intensive applications. The processor performance impact due to these brief
periods of TCC activation is expected to be minor and hence not detectable.
64
Parameter
Forward Bias Current
Emitter Current
Transistor Ideality
Series Resistance
in
Table
19.
FW
, represents the deviation from ideal diode behavior as exemplified
Q
(qV
/n
kT)
*(e
BE
Q
-1)
s
= saturation current, q = electronic charge, V
S
, provided in the Diode Model Table
T
Table
) is 1.000. Given that most diodes are not perfect, the designers
trim
value that more closely matches the behavior of the diodes in
trim
T
= T
error(nf)
measured
is the offset in degrees C, T
is the diode ideality assumed by the temperature
trim
Min
Typ
Max
5
200
5
200
0.997
1.001
1.005
0.3
0.760
2.79
4.52
6.24
= voltage across the transistor
BE
19. In most sensing devices, an expected value
* (1 - n
/n
)
actual
trim
is in Kelvin, n
measured
Thermal Specifications
Unit
Notes
µA
1, 2
µA
1
3, 4, 5
3, 4
Ω
3, 6
(Table
19) can be used for
each
trim,
is the measured
actual
Datasheet
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