47.
Packaging Information
47.1. Thermal Considerations
47.1.1. Thermal Resistance Data
The following table summarizes the thermal resistance data depending on the package.
Table 47-1. Thermal Resistance Data
Package Type
θ
JA
θ
JC
48-pin TQFP
64.2°C/W
12.3°C/W
64-pin TQFP
60.8°C/W
12.0°C/W
100-pin TQFP
58.5°C/W
12.7°C/W
48-pin QFN
32.4°C/W
11.2°C/W
64-pin QFN
32.7°C/W
10.8°C/W
49-pin WLCSP
37.3°C/W
5.8°C/W
Related Links
on page 1183
47.1.2. Junction Temperature
The average chip-junction temperature, T
J
, in °C can be obtained from the following:
1.
T
J
= T
A
+ (P
D
x θ
JA
)
2.
T
J
= T
A
+ (P
D
x (θ
HEATSINK
+ θ
JC
))
where:
•
θ
JA
= Package thermal resistance, Junction-to-ambient (°C/W), see Thermal Resistance Data
•
θ
JC
= Package thermal resistance, Junction-to-case thermal resistance (°C/W), see Thermal
Resistance Data
•
θ
HEATSINK
= Thermal resistance (°C/W) specification of the external cooling device
•
P
D
= Device power consumption (W)
•
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.
Related Links
on page 1147
on page 1183
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
1183