Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105 Data Sheet
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