BCM43903 Datasheet, PDF (84/87 Pages) Cypress Semiconductor – WICED™ IEEE 802.11 b/g/n SoC with an Embedded Applications Processor

BCM43903 Preliminary Data Sheet
Thermal Information
Section 19: Thermal Information
Package Thermal Characteristics
Table 31: Package Thermal Characteristics^a
Characteristic
WLBGA
_JA (°C/W) (value in still air)
_JB (°C/W)
_JC (°C/W)
_JT (°C/W)
_JB (°C/W)
Maximum Junction Temperature T_j (°C)
Maximum power dissipation (W)
31.72
3.95
2.16
4.3
9.28
113.9
1.38
a. No heat sink, TA = 70°C. This is an estimate based on a 4-layer PCB that conforms to EIA/JESD51–7. Air
velocity is 0 m/s.
Junction Temperature Estimation and PSI_JT Versus THETA_JC
Package thermal characterization parameter PSI–J_T (_JT) yields a better estimation of actual junction
temperature (T_J) versus using the junction-to-case thermal resistance parameter Theta–J_C (_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:
T_J = T_T + P x _JT
Where:
• T_J = Junction temperature at steady-state condition (°C)
• T_T = 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 13: “Environmental Ratings,” on page 58.
Broadcom^®
March 12, 2016 • 43903-DS102-R
BROADCOM CONFIDENTIAL
Page 83