BCM4319 Preliminary Data Sheet
Package Information
Section 16: Package Information
Package Thermal Characteristics
Table 31: 138-Ball WLBGA Package Thermal Characteristicsa
0 fpm,
0 mps
100 fpm,
0.508 mps
200 fpm,
0.508 mps
400 fpm,
0.508 mps
600 fpm,
0.508 mps
Airflow
29.79
1.06
0.09
0.03
27.34
–
26.59
–
25.79
–
25.29
–
θJA (°C/W)
θJB (°C/W)
θJC (°C/W)
ψJT (°C/W)
–
–
–
–
0.03
0.03
0.03
0.03
a. No heat sink, TA = 85ºC. This is an estimate based on 2-layer PCB and P = 1.1W.
Junction Temperature Estimation and PSI VERSUS THETA
JT
JC
Package thermal characterization parameter PSI-JT (Ψ ) yields a better estimation of actual junction
JT
temperature (T ) versus using the junction-to-case thermal resistance parameter Theta-JC (Θ ). The reason
J
JC
for this is Θ assumes that all the power is dissipated through the top surface of the package case. In actual
JC
applications, some of the power is dissipated through the bottom and sides of the package. Ψ takes into
JT
account power dissipated through the top, bottom, and sides of the package.
The equation for calculating the device junction temperature is as follows:
TJ = TT + P × ΨJT
Where:
•
•
•
•
T = Junction temperature at steady-state condition (°C)
J
T = Package case top center temperature at steady-state condition (°C)
T
P = Device power dissipation (Watts)
Ψ
= Package thermal characteristics; no airflow (°C/W)
JT
Broadcom®
Single-Chip IEEE 802.11™ a/b/g/n MAC/Baseband/Radio
Page 80
April 2, 2014 • 4319-DS05-R
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