Intel PentiumD 950 HH80553PG0964M Manuale Utente
Codici prodotto
HH80553PG0964M
Datasheet
89
Thermal Specifications and Design Considerations
5.
The series resistance, R
T
, is provided to allow for a more accurate measurement of the
junction temperature. R
T
, as defined, includes the lands of the processor but does not
include any socket resistance or board trace resistance between the socket and the
external remote diode thermal sensor. R
external remote diode thermal sensor. R
T
can be used by remote diode thermal sensors
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:
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:
T
error
= [R
T
* (N-1) * I
FWmin
] / [nk/q * ln N]
where T
error
= sensor temperature error, N = sensor current ratio, k = Boltzmann Constant, q = electronic
charge.
NOTES:
1.
1.
Intel does not support or recommend operation of the thermal diode under reverse bias.
2.
Same as I
FW
3.
Characterizedacross a range of 50 – 80 °C.
4.
Not 100% tested. Specified by design characterization.
5.
The ideality factor, nQ, represents the deviation from ideal transistor model behavior as
exemplified by the equation for the collector current:
exemplified by the equation for the collector current:
I
C
= I
S
* (e
qV
BE
/n
Q
kT
–1)
Where I
S
= saturation current, q = electronic charge, V
BE
= voltage across the transistor base emitter
junction (same nodes as VD), k = Boltzmann Constant, and T = absolute temperature (Kelvin).
6.
The series resistance, R
T,
provided in the Diode Model Table (
) can be used for
more accurate readings as needed.
When calculating a temperature based on 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 some are
capable of also measuring the series resistance. Calculating the temperature is then
accomplished using the equations listed under
. In most temperature sensing
devices, an expected value 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
trim
) will be 1.000. Given that most diodes
are not perfect, the designers usually select an n
trim
value that more closely matches
the behavior of the diodes in the processor. If the processors diode ideality deviates
from that of n
trim
, each calculated temperature will be offset by a fixed amount. This
temperature offset can be calculated with the equation:
T
error(nf)
= T
measured
X (1 - n
actual
/n
trim
)
Where T
error(nf)
is the offset in degrees C, T
measured
is in Kelvin, n
actual
is the measured
ideality of the diode, and n
trim
is the diode ideality assumed by the temperature
sensing device.
To improve the accuracy of diode based temperature measurements, a new register
containing Thermal Diode Offset data has been added to the processor. During
manufacturing each processor thermal diode will be evaluated for its behavior relative
to a theoretical diode. Using the equation above, the temperature error created by the
difference between n
trim
and the actual ideality of the particular processor will be
Table 30.
Thermal “Diode” Parameters using Transistor Model
Symbol
Parameter
Min
Typ
Max
Unit
Notes
I
FW
Forward Bias Current
5
-
200
µA
1, 2
I
E
Emitter Current
5
200
n
Q
Transistor Ideality
0.997
1.001
1.005
-
3, 4, 5
Beta
0.391
0.760
3, 4
R
T
Series Resistance
2.79
4.52
6.24
Ω
3, 6