Features
6.3.1
Thermal Diode
The Pentium 4 processor on 0.13 micron process 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 6-2 and Table 6-3 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 6-2. Thermal Diode Parameters
Symbol
IFW
Parameter
Forward Bias Current
Min
Typ
Max
Unit
Notes1
5
300
1.0030
Ω
µA
1
n
Diode Ideality Factor
Series Resistance
1.0011
1.0021
3.64
2,3,4
RT
2,3,4,5
NOTES:
1. Intel does not support or recommend operation of the thermal diode under reverse bias.
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
equation:
I
FW=Is *(e(qVD/nkT) -1)
Where IS = saturation current, q = electronic charge, VD = voltage across the diode, k = Boltzmann Constant,
and T = absolute temperature (Kelvin).
5. The series resistance, RT, is provided to allow for a more accurate measurement of the diode junction
temperature. RT as defined includes the pins of the processor but does not include any socket resistance or
board trace resistance between the socket and the external remote diode thermal sensor. RT 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:
Terror = [RT*(N-1)*IFWmin]/[(nk/q)*ln N]
Where Terror = sensor temperature error, N = sensor current ration, k = Boltzmann Constant, q = electronic
charge.
Table 6-3. Thermal Diode Interface
Pin Name
Pin Number
Pin Description
THERMDA
THERMDC
B3
C4
diode anode
diode cathode
76
Intel® Pentium® 4 Processor on 0.13 Micron Process Datasheet
INTEL [ INTEL ]
