Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105 Data Sheet
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Product codes
ATEVK1105
787
AT32UC3A
39. Mechanical Characteristics
39.1
Thermal Considerations
39.1.1
Thermal Data
summarizes the thermal resistance data depending on the package.
39.1.2
Junction Temperature
The average chip-junction temperature, T
J
, in °C can be obtained from the following:
1.
2.
2.
where:
• θ
• θ
JA
= package thermal resistance, Junction-to-ambient (°C/W), provided in
• θ
JC
= package thermal resistance, Junction-to-case thermal resistance (°C/W), provided in
• θ
HEAT SINK
= cooling device thermal resistance (°C/W), provided in the device datasheet.
• P
D
= device power consumption (W) estimated from data provided in the section
• T
A
= ambient temperature (°C).
From the first equation, the user can derive the estimated lifetime of the chip and decide if a
cooling device is necessary or not. If a cooling device is to be fitted on the chip, the second
equation should be used to compute the resulting average chip-junction temperature
T
J
in °C.
Table 39-1.
Thermal Resistance Data
Symbol
Parameter
Condition
Package
Typ
Unit
θ
JA
Junction-to-ambient thermal resistance
Still Air
TQFP100
43.4
⋅
C/W
θ
JC
Junction-to-case thermal resistance
TQFP100
5.5
θ
JA
Junction-to-ambient thermal resistance
Still Air
LQFP144
39.8
⋅
C/W
θ
JC
Junction-to-case thermal resistance
LQFP144
8.9
T
J
T
A
P
D
θ
JA
×
(
)
+
=
T
J
T
A
P
(
D
θ
× (
HEATSINK
θ
JC
) )
+
+
=
32058K
AVR32-01/12