SAM4L Datasheet, PDF (1157/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
43. Mechanical Characteristics
43.1 Thermal Considerations
43.1.1
43.1.2
Thermal Data
Table 43-1 summarizes the thermal resistance data depending on the package.
Table 43-1. Thermal Resistance Data
Symbol Parameter
Condition Package
Typ Unit
θ_JA
Junction-to-ambient thermal resistance Still Air
TQFP100
48.1
⋅C/W
θ_JC
Junction-to-case thermal resistance
TQFP100 13.3
θ_JA
Junction-to-ambient thermal resistance Still Air
VFBGA100 31.1
⋅C/W
θ_JC
Junction-to-case thermal resistance
VFBGA100 6.9
θ_JA
Junction-to-ambient thermal resistance Still Air
WLCSP64
26.9
⋅C/W
θ_JC
Junction-to-case thermal resistance
WLCSP64
0.2
θ_JA
Junction-to-ambient thermal resistance Still Air
TQFP64
49.6
⋅C/W
θ_JC
Junction-to-case thermal resistance
TQFP64
13.5
θ_JA
Junction-to-ambient thermal resistance Still Air
QFN64
22.0
⋅C/W
θ_JC
Junction-to-case thermal resistance
QFN64
1.3
θ_JA
Junction-to-ambient thermal resistance Still Air
TQFP48
51.1
⋅C/W
θ_JC
Junction-to-case thermal resistance
TQFP48
13.7
θ_JA
Junction-to-ambient thermal resistance Still Air
QFN48
24.9
⋅C/W
θ_JC
Junction-to-case thermal resistance
QFN48
1.3
Junction Temperature
The average chip-junction temperature, T_J, in °C can be obtained from the following:
1. T_J = T_A + (P_D × θ_JA)
2. T_J = T_A + (P _D × (θ _HEATSINK + θ_JC ) )
where:
• θ_JA = package thermal resistance, Junction-to-ambient (°C/W), provided in Table 43-1.
• θ_JC = package thermal resistance, Junction-to-case thermal resistance (°C/W), provided in
Table 43-1.
• 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 Section 42.4 on page
1109.
• 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.
42023C–SAM–02/2013
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