Intel Pentium 4 Processor Extreme Edition on 0.13 Micron Process in the 775-Land Package Datasheet

Datasheet 73
Thermal Specifications and Design Considerations
5.2.5 Thermal Diode
The processor incorporates an on-die thermal diode. A thermal sensor located on the system board
may monitor the die temperature of the processor for thermal management/long term die
temperature change purposes. Table 5-2 and Table 5-3 provide the diode parameter and interface
specifications. This thermal diode is separate from the Thermal Monitor’s thermal sensor and
cannot be used to predict the behavior of the Thermal Monitor.
§
Table 5-2. Thermal Diode Parameters
Symbol Parameter Min Typ Max Unit Notes
I
FW
Forward Bias Current 5 — 300 µA
1
NOTES:
1. Intel does not support or recommend operation of the thermal diode under reverse bias.
n Diode Ideality Factor 1.0011 1.0021 1.0030 —
2, 3, 4
2. Characterized at 75 °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 equa-
tion:
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).
R
T
Series Resistance — 3.64 — Ω
2, 3, 5
5. The series resistance, R
T
, is provided to allow for a more accurate measurement of the diode 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
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:
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.
Table 5-3. Thermal Diode Interface
Signal Name Land Number Signal Description
THERMDA AL1 diode anode
THERMDC AK1 diode cathode