BCM43455 Preliminary Data Sheet
Package Information
Section 22: Package Information
Package Thermal Characteristics
Table 64: Package Thermal Characteristicsa
Characteristic
WLBGA
38.73
1.97
JA (°C/W) (value in still air)
JB (°C/W)
3.16
JC (°C/W)
JT (°C/W)
JB (°C/W)
9.3
16.21
123.6
1.38
Maximum Junction Temperature Tj (°C)
Maximum Power Dissipation (W)
a. No heat sink, TA = 70°C. This is an estimate, based on a 4-layer PCB that conforms to EIA/JESD51–7
(101.6 mm × 101.6 mm × 1.6 mm) and P = 1.119W continuous dissipation.
Junction Temperature Estimation and PSIJT Versus THETAJC
Package thermal characterization parameter PSI–JT ( ) yields a better estimation of actual junction
JT
temperature (TJ) versus using the junction-to-case thermal resistance parameter Theta–JC (JC). The reason
for this is that JC assumes that all the power is dissipated through the top surface of the package case. In actual
applications, some of the power is dissipated through the bottom and sides of the package. JT takes into
account power dissipated through the top, bottom, and sides of the package. The equation for calculating the
device junction temperature is:
TJ = TT + P x JT
Where:
•
•
•
•
TJ = Junction temperature at steady-state condition (°C)
TT = Package case top center temperature at steady-state condition (°C)
P = Device power dissipation (Watts)
JT = Package thermal characteristics; no airflow (°C/W)
Environmental Characteristics
For environmental characteristics data, see Table 25: “Environmental Ratings,” on page 98.
Broadcom®
November 5, 2015 • 43455-DS109-R
BROADCOM CONFIDENTIAL
Page 154
CYPRESS [ CYPRESS ]
