SBVS360A February   2020  – November 2020 TPS7B85-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Enable (EN)
      2. 7.3.2 Power-Good (PG)
        1. 7.3.2.1 Adjustable Power-Good (PGADJ)
      3. 7.3.3 Adjustable Power-Good Delay Timer (DELAY)
      4. 7.3.4 Sense Comparator
      5. 7.3.5 Undervoltage Lockout
      6. 7.3.6 Thermal Shutdown
      7. 7.3.7 Current Limit
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Functional Mode Comparison
      2. 7.4.2 Normal Operation
      3. 7.4.3 Dropout Operation
      4. 7.4.4 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Input and Output Capacitor Selection
      2. 8.1.2 Dropout Voltage
      3. 8.1.3 Reverse Current
      4. 8.1.4 Power Dissipation (PD)
        1. 8.1.4.1 Thermal Performance Versus Copper Area
      5. 8.1.5 Estimating Junction Temperature
      6. 8.1.6 SI Pin
        1. 8.1.6.1 Calculating the Sense Input (SI) Pin Threshold
        2. 8.1.6.2 Different Uses for the Sense Input Pin
          1. 8.1.6.2.1 Monitoring Input Voltage
          2. 8.1.6.2.2 Creating OV and UV Power-Good
          3. 8.1.6.2.3 Monitoring a Separate Supply Voltage
      7. 8.1.7 Pulling Up the SO and PG Pins to a Different Voltage
      8. 8.1.8 Power-Good
        1. 8.1.8.1 Setting the Adjustable Power-Good Threshold
        2. 8.1.8.2 Setting the Adjustable Power-Good Delay
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Capacitor
        2. 8.2.2.2 Output Capacitor
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Package Mounting
      2. 10.1.2 Board Layout Recommendations to Improve PSRR and Noise Performance
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.4.1 Thermal Performance Versus Copper Area

The most used thermal resistance parameter, RθJA, is highly dependent on the heat-spreading capability built into the particular PCB design, and therefore varies according to the total copper area, copper weight, and location of the planes. The RθJA recorded in the Thermal Information table in the Section 6 section is determined by the JEDEC standard (see Figure 8-1), PCB, and copper-spreading area, and is only used as a relative measure of package thermal performance. For a well-designed thermal layout, RθJA is actually the sum of the package junction-to-case (bottom) thermal resistance (RθJCbot) plus the thermal resistance contribution by the PCB copper.

GUID-2BF2C0B9-4F00-41EC-AD78-3CA4192C654F-low.gifFigure 8-1 JEDEC Standard 2s2p PCB

Figure 8-2 and Figure 8-3 depict the functions of RθJA and ψJB versus copper area and thickness. These plots are generated with a 101.6-mm x 101.6-mm x 1.6-mm PCB of two and four layers. For the four-layer board, the inner planes use a 1-oz copper thickness. Outer layers are simulated with both a 1-oz and 2-oz copper thickness. A 4 x 4 array of thermal vias of 300-µm drill diameter and 25-µm Cu plating is located beneath the thermal pad of the device. The thermal vias connect the top layer, the bottom layer and, in the case of the 4-layer board, the first inner GND plane. Each of the layers has a copper plane of equal area.

GUID-20201023-CA0I-PT5C-L1VM-XHSVK3RRCLNB-low.gifFigure 8-2 RθJA vs Copper Area 2s2p DRC Package
GUID-20201023-CA0I-XMKL-1JMW-X7HRQF46R7FD-low.gifFigure 8-3 R ψJB vs Copper Area 2s2p DRC Package