Revision 1.1
343
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G
8.0
Package Specifications
8.1
The junction-to-case thermal resistance (
θ
JC
)
of the TEPBGA package shown in Table 8-1
can be used to calculate the
junction (die) temperature under any given circumstance.
THERMAL CHARACTERISTICS
Note that there is no specification for maximum junction temperature given since the operation of the TEPBGA device is
guaranteed to a case temperature range of 0
°
C to 85
°
C (see Table 7-2 on page 281). As long as the case temperature of
the device is maintained within this range, the junction temperature of the die will also be maintained within its allowable
operating range. However, the die (junction) temperature under a given operating condition can be calculated by using the
following equation:
T
J
= T
C
+ (P *
θ
JC
)
where:
T
J
= Junction temperature (
°
C)
T
C
= 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 temperature (T
A
)
is determined by the system designer based on system configuration, extremes of the operating environment, and whether
active thermal management (via Suspend Modulation) of the GX1 processor 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 maximum 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
T
A
= Max ambient temperature (
°
C)
T
C
= 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 equa-
tion can be simplified to:
where:
θ
CA
=
θ
SA
= Max heatsink-to-ambient thermal resistance (
°
C/W) allowed for thermal solution
The calculated
θ
CA
value (examples shown in Table 8-2 on page 344) represents the maximum allowed thermal resistance
of the selected cooling solution which is required to maintain the maximum T
C
(shown in Table 7-2 on page 281) for the
application in which the device is used.
Table 8-1.
θ
JC
(×C/W) for SC1100
Package
Max
(
°
C/W)
TEPBGA without copper heat spreader
TEPBGA with copper heat spreader
7
5
θ
CS
+
θ
SA
=
T
C
T
A
P
θ
CA
=
T
C
T
A
P