Chapter 7
Electrical Data
39
24309E—March 2002
AMD Athlon™ XP Processor Model 6 Data Sheet
Preliminary Information
7.14
Thermal Diode Characteristics
Thermal Diode Electrical Characteristics.
Table 14 shows the
AMD Athlon XP processor model 6 electrical characteristics of
the on-die thermal diode.
Table 14. Thermal Diode Electrical Characteristics
Symbol
Parameter Description
Min
Nom
Max
Units
Notes
I
fw
Forward bias current
5
300
µA
1
n
Diode ideality factor
1.002
1.008
1.016
2, 3, 4, 5
Notes:
1. The sourcing current should always be used in forward bias only.
2. Characterized at 95°C with a forward bias current pair of 10
µ
A and 100
µ
A.
3. Not 100% tested. Specified by design and limited characterization.
4. The diode ideality factor, n, is a correction factor to the ideal diode equation.
For the following equations, use the following variables and constants:
n
Diode ideality factor
k
Boltzmann constant
q
Electron charge constant
T
Diode temperature (Kelvin)
V
BE
Voltage from base to emitter
I
C
Collector current
I
S
Saturation current
N
Ratio of collector currents
The equation for V
BE
is:
By sourcing two currents and using the above equation, a difference in base emitter voltage
can be found that leads to the following equation for temperature:
5. If a different sourcing current pair is used other than 10
µ
A and 100
µ
A, the following equation
should be used to correct the temperature. Subtract this offset from the temperature measured
by the temperature sensor.
For the following equations, use the following variables and constants:
I
high
High sourcing current
I
low
Low sourcing current
T
offset
(in °C) can be found using the following equation:
V
BE
nkT
q
---------
I
C
I
S
-----
ln
⋅
=
T
∆
V
BE
n
N
( )
ln
k
q
---
⋅
⋅
-----------------------------
=
T
offset
6.0 10
4
⋅
(
)
I
high
I
low
–
(
)
I
high
I
low
-----------
ln
--------------------------------
⋅
2.34
–
=