SBVS343A March   2019  – September 2019

PRODUCTION DATA.

1. Features
2. Applications
3. Description
1.     Device Images
4. Revision History
5. Pin Configuration and Functions
6. Specifications
7. Detailed Description
1. 7.1 Overview
2. 7.2 Functional Block Diagram
3. 7.3 Feature Description
4. 7.4 Device Functional Modes
8. Application and Implementation
1. 8.1 Application Information
2. 8.2 Typical Application
1. 8.2.1 Design Requirements
2. 8.2.2 Detailed Design Procedure
3. 8.2.3 Application Curves
9. Power Supply Recommendations
10. 10Layout
11. 11Device and Documentation Support
1. 11.1 Device Support
1. 11.1.1 Development Support
2. 11.1.2 Device Nomenclature
2. 11.2 Documentation Support
4. 11.4 Community Resources
6. 11.6 Electrostatic Discharge Caution
7. 11.7 Glossary
12. 12Mechanical, Packaging, and Orderable Information

• PWP|14
• PWP|14

8.1.9 Estimating Junction Temperature

The JEDEC standard recommends the use of psi (Ψ) thermal metrics to estimate the junction temperatures of the linear regulator when in circuit on a typical PCB board application. These metrics are not thermal resistance parameters and instead offer a practical and relative way to estimate junction temperature. These psi metrics are determined to be significantly independent of the copper area available for heat spreading. The Thermal Information table lists the primary thermal metrics, which are the junction-to-top characterization parameter (ψJT) and junction-to-board characterization parameter (ψJB). These parameters provide two methods for calculating the junction temperature (TJ). As described in the Semiconductor and IC Package Thermal Metrics application report, use the junction-to-top characterization parameter (ψJT) with the temperature at the center-top of device package (TT) to calculate the junction temperature. As described in the Semiconductor and IC Package Thermal Metrics application report, use the junction-to-board characterization parameter (ψJB) with the PCB surface temperature 1 mm from the device package (TB) to estimate the junction temperature.

Equation 6. TJ = TT + ψJT × PD_Total

where

• PD_Total is the total dissipated power in the device
• TT is the temperature at the center-top of the device package
Equation 7. TJ = TB + ψJB × PD

where

• TB is the PCB surface temperature measured 1 mm from the device package and centered on the package edge

For detailed information on the thermal metrics and how to use them, see the Semiconductor and IC Package Thermal Metrics application report.