THERMAL CHARACTERISTICS
The thermal specifications for the ÉlanSC400 and
ÉlanSC410 microcontrollers are given as a TCASE (the
case temperature) specification. The 33-MHz and
66-MHz devices are specified for operation when
TCASE is with the range of 0°C–+95°C. The 100-MHz
device is specified for operation when TCASE is within
the range of 0°C–+85°C. TCASE can be measured in
any environment to determine whether the microcon-
troller is within specified operating range. The case
temperature should be measured at the center of the
top surface opposite the solder balls.
where:
TJ is the junction temperature (°C).
TA is the ambient temperature (°C).
TCASE is the case temperature (°C).
ΨJ-T is the junction-to-case thermal resistance (°C/W).
θJA is the junction-to-ambient thermal resistance
(°C/W).
P is the maximum power consumption (W).
The ambient temperature (TA) is guaranteed as long as
TCASE is not violated. The ambient temperature can be
calculated from ΨJ-T and θJA from the following
equations:
The values for θJA and ΨJ-T are given in Table 52 for
the BGA 292 package. These numbers are valid only
for packages with all 292 balls soldered to a board with
two power planes and two signal planes.
TJ = TCASE + P • ΨJ-T
TA = TJ – P • θJA
Table 53 shows the TA allowable (without exceeding
TCASE) at various airflows and operating frequencies.
P is calculated using the ICC at 3.3 V as tabulated in the
DC Characteristics section beginning on page 86.
TCASE = TA + P • (θJA – ΨJ-T
)
Table 52. Thermal Resistance ΨJ-T and θJA (°C/W) for the 292-BGA Package)
Airflow in Feet/Minute (m/s)
Thermal
Resistance
0
200
(1.01)
20.5
6.2
400
(2.03)
19.0
6.2
600
(3.04)
18.1
6.2
800
(4.06)
17.4
6.2
(0)
θJA
25.0
6.2
ΨJ-T
Table 53. Maximum TA at Various Airflows in °C
Airflow in Feet/Minute (m/s)
400
0
200
600
(3.04)
87.8
80.4
63.4
800
Maximum TA
(0)
(1.01)
86.4
77.5
59.0
(2.03)
87.3
79.3
61.7
(4.06)
88.3
81.3
64.6
at 33 MHz
at 66 MHz
at 100 MHz
83.7
72.0
50.8
130
Élan™SC400 and ÉlanSC410 Microcontrollers Data Sheet
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