SLVSBB2F May   2012  – August 2024 TPS65131-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Power Conversion
      2. 7.3.2 Control
      3. 7.3.3 Output Rails Enable or Disable
      4. 7.3.4 Load Disconnect
      5. 7.3.5 Soft Start
      6. 7.3.6 Overvoltage Protection
      7. 7.3.7 Undervoltage Lockout
      8. 7.3.8 Overtemperature Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-Save Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 TPS65131-Q1 With VPOS = 10.5V, VNEG = –10V
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Programming the Output Voltage
          1. 8.2.3.1.1 Boost Converter
          2. 8.2.3.1.2 Inverting Converter
          3. 8.2.3.1.3 Inductor Selection
        2. 8.2.3.2 Capacitor Selection
          1. 8.2.3.2.1 Input Capacitor
          2. 8.2.3.2.2 Output Capacitors
        3. 8.2.3.3 Rectifier Diode Selection
        4. 8.2.3.4 External P-MOSFET Selection
        5. 8.2.3.5 Stabilizing the Control Loop
          1. 8.2.3.5.1 Feedforward Capacitors
          2. 8.2.3.5.2 Compensation Capacitors
      4. 8.2.4 Analog Supply Input Filter
        1. 8.2.4.1 RC-Filter
        2. 8.2.4.2 LC-Filter
      5. 8.2.5 Thermal Information
      6. 8.2.6 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Mechanical Data
    2. 11.2 Tape and Reel Information
8.2.3.1.2 Inverting Converter

An external resistor divider adjusts the output voltage of the TPS65131-Q1 inverting converter stage. Connect this divider to the FBN pin. Unlike the feedback divider at the boost converter, the reference point of the feedback divider is not GND, but Vref. So the typical value of the voltage at the FBN pin is 0V. The minimum recommended output voltage at the inverting converter is –15V. Feedback divider current considerations are similar to the considerations for the boost converter. For the same reasons, the feedback divider current should be in the range of 5µA or higher. The voltage across R4 is 1.213V. Based on those values, the recommended value for R4 should be lower than 200kΩ in order to set the divider current at the required value.

Calculate the value of resistor R3, as a function of the needed output voltage (VNEG), with Equation 2:

Equation 2. TPS65131-Q1

In this example, with R4 = 121.2kΩ, choose R3 = 1MΩ to set VNEG = –10V.