BCM4354 datasheet(186/192 Pages) CYPRESS

Part #	BCM4354

Description	Single-Chip 5G Wi-Fi IEEE 802.11ac 2횞2 MAC/ Baseband/Radio with Integrated Bluetooth 4.1 and FM Receiver

PDF	192 Pages

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Manufacturer	CYPRESS [Cypress Semiconductor]

Direct Link	http://www.cypress.com

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186 / 192 page

Junction Temperature Estimation and PSIJT Versus ThetaJC

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 185

Junction Temperature Estimation and PSIJT Versus ThetaJC

The package thermal characterization parameter PSIJT (JT) yields a better estimation of actual junction

temperature (TJ) than using the junction-to-case thermal resistance parameter ThetaJC (θJC). The reason for

this is that θJC is based on the assumption that all the power is dissipated through the top surface of the package

case. In actual applications, however, some of the power is dissipated through the bottom and sides of the

package.

JT takes into account the 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 30: “Environmental Ratings,” on page 126.

BCM4354 Datasheet(PDF) 186 Page - Cypress Semiconductor