Thermal Specifications and Design Considerations
Table 15. Thermal Diode Interface
Signal Name
Pin/Ball Number
Signal Description
THERMDA
THERMDC
E4
E5
Thermal diode anode
Thermal diode cathode
Table 16. Thermal Diode Parameters using Transistor Model
Symbol
Parameter
Min
Typ
Max
Unit
Notes
IFW
IE
Forward Bias Current
Emitter Current
5
—
—
200
200
μA
μA
1
1
5
nQ
Transistor Ideality
0.997
0.25
2.79
1.001
—
1.015
0.65
6.24
2,3,4
2,3
2,5
Beta
RT
Series Resistance
4.52
Ω
NOTES:
1.
Intel does not support or recommend operation of the thermal diode under reverse
bias.
2.
3.
4.
Characterized across a temperature range of 50–100°C.
Not 100% tested. Specified by design characterization.
The ideality factor, nQ, represents the deviation from ideal transistor model behavior as
exemplified by the equation for the collector current:
/n
IC = IS * (e qV kT –1)
BE
Q
where IS = saturation current, q = electronic charge, VBE = voltage across the
transistor base emitter junction (same nodes as VD), k = Boltzmann Constant, and
T = absolute temperature (Kelvin).
5.
The series resistance, RT, provided in the Diode Model Table (Table 16) can be used for
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 equation listed under Table 16. In most 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 ntrim) will be 1.000. Given that most diodes are not
perfect, the designers usually select an ntrim value that more closely matches the
behavior of the diodes in the processor. If the processor diode ideality deviates from
that of the ntrim, each calculated temperature will be offset by a fixed amount. This
temperature offset can be calculated with the equation:
Terror(nf) = Tmeasured * (1 – nactual/ntrim
)
Where Terror(nf) is the offset in degrees C, Tmeasured is in Kelvin, nactual is the measured
ideality of the diode, and ntrim is the diode ideality assumed by the temperature
sensing device.
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Datasheet
INTEL [ INTEL ]
