Intel Pentium 4 Processor on 90 nm Process Thermal and Mechanical Design Guidelines

Appendix E: TTV Metrology
R
Intel
®
Pentium
®
4 on 90 nm Process Thermal Design Guide 79
7. Refer to Section 3.3.2 to setup the thermocouples used for T
A
measurement, and connect them
to a thermocouple meter or data logger.
8. Set the voltage of the DC power supply to the value calculated from the targeted power level
and the heater resistance, if the DC-power supplier uses a voltage-control mode
(e.g.,
PowerResistanceHeaterVoltage ×=
). Alternatively, an appropriate current can be
set to the DC-power supplier if the DC-power supplier uses a current-control mode.
9. Calculate the actual power P
D
applied to the heater resistor by multiplying the readings from
the TTV voltage meter and the calculated shunt resistor current (Current = V
SHUNT
/ R
SHUNT
).
As the heater heats up, the heater resistance will increase slightly and the current will
decrease resulting in a small drop of power if a voltage-control mode is used. The power
supply voltage has to be increased to compensate for the drop in the current to maintain a
constant power. Die resistance variations restrict the capability of predicting the power
supply voltage and current settings. (Table 9 can be used as a general reference or starting
point to acquire the desired actual power.)
Table 9. Desired Power Targets
Desired Die Power Level Power Supply Setting
70 40 V and 1.5 A
80 49 V and 1.6 A
90 53V and 1.7 A
100 56V and 1.8 A
110 60 V and 1.9 A
10. Wait for one hour to reach the stable condition before reading the case temperature (T
C
) and
the local ambient temperatures (T
A
) from the thermocouples. If a data logger is used, sample
two minutes of steady state data at 1 Hz and average the temperatures over that time period.
Average all the T
A
thermocouple temperatures to arrive at a single T
A
measurement.
11. Calculate the raw case-to-ambient thermal characterization parameter (Ψ
CA
) based on
equation 1 given in Section 3.2.3. This equation is shown below.
Ψ
CA
= (T
C
- T
A
) / P
D
12. Multiply raw result with Ψ
CA
correction factor in Table 10 to arrive at final adjusted Ψ
CA
.