
AMD Geode SC1200/SC1201 Processor Data Book
457
10
Package Specifications
Revision 7.1
10.0Package Specifications
10.1
Thermal Characteristics
The junction-to-case thermal resistance (
θ
JC) of the pack-
ages shown in
Table 10-1 can be used to calculate the
junction (die) temperature under any given circumstance.
Note that there is no specification for maximum junction
temperature given since the operation of the device is guar-
anteed to a case temperature range of 0
°C to 85°C (see
the device is maintained within this range, the junction tem-
perature of the die will also be maintained within its allow-
able
operating
range.
However,
the
die
(junction)
temperature under a given operating condition can be cal-
culated by using the following equation:
TJ = TC + (P * θJC)
where:
TJ = Junction temperature (°C)
TC = Case temperature at top center of package (°C)
P = Maximum power dissipation (W)
θ
JC = Junction-to-case thermal resistance (°C/W)
These examples are given for reference only. The actual
value used for maximum power (P) and ambient tempera-
ture (TA) is determined by the system designer based on
system configuration, extremes of the operating environ-
ment, and whether active thermal management (via Sus-
pend Modulation) of the GX1 module is employed.
A maximum junction temperature is not specified since a
maximum case temperature is. Therefore, the following
equation can be used to calculate the maximum thermal
resistance required of the thermal solution for a given max-
imum ambient temperature:
where:
θ
CS = Max case-to-heatsink thermal resistance (°C/W)
allowed for thermal solution
θ
SA = Max heatsink-to-ambient thermal resistance (°C/W)
allowed for thermal solution
TA = Max ambient temperature (°C)
TC = Max case temperature at top center of package (°C)
P
= Maximum power dissipation (W)
If thermal grease is used between the case and heatsink,
θ
CS will reduce to about 0.01 °C/W. Therefore, the above
equation can be simplified to:
where:
θ
CA = θSA = Max heatsink-to-ambient thermal resistance
(
°C/W) allowed for thermal solution
The calculated
θ
represents the maximum allowed thermal resistance of the
selected cooling solution which is required to maintain the
application in which the device is used.
Table 10-1.
θ
JC (×C/W)
Package
Max (
°C/W)
EBGA
1
TEPBGA
5
θ
CS + θSA =
TC TA
P
θ
CA =
TC TA
P
Table 10-2. Case-to-Ambient Thermal Resistance Example @ 85
°C
Core Voltage
(VCORE)
(Nominal)
Core
Frequency
Maximum
Power (W)
θ
CA for Different Ambient Temperatures (°C/W)
20
°C25°C30°C35°C40°C
1.8V
266 MHz
3.32
19.58
18.07
16.57
15.06
13.55