SNVSBC5A December   2020  – December 2022 TPS548B28

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 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  Internal VCC LDO And Using External Bias On VCC Pin
      2. 7.3.2  Enable
      3. 7.3.3  Output Voltage Setting
        1. 7.3.3.1 Remote Sense
      4. 7.3.4  Internal Fixed Soft Start and External Adjustable Soft Start
      5. 7.3.5  External REFIN For Output Voltage Tracking
      6. 7.3.6  Frequency and Operation Mode Selection
      7. 7.3.7  D-CAP3™ Control Mode
      8. 7.3.8  Low-side FET Zero-Crossing
      9. 7.3.9  Current Sense and Positive Overcurrent Protection
      10. 7.3.10 Low-side FET Negative Current Limit
      11. 7.3.11 Power Good
      12. 7.3.12 Overvoltage and Undervoltage Protection
      13. 7.3.13 Out-Of-Bounds (OOB) Operation
      14. 7.3.14 Output Voltage Discharge
      15. 7.3.15 UVLO Protection
      16. 7.3.16 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Auto-Skip Eco-mode™ Light Load Operation
      2. 7.4.2 Forced Continuous-Conduction Mode
      3. 7.4.3 Powering the Device From a 12-V Bus
      4. 7.4.4 Powering the Device From a 3.3-V Bus
      5. 7.4.5 Powering the Device From a Split-rail Configuration
  8. 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
        1. 8.2.2.1  Output Voltage Setting Point
        2. 8.2.2.2  Choose the Switching Frequency and the Operation Mode
        3. 8.2.2.3  Choose the Inductor
        4. 8.2.2.4  Set the Current Limit (TRIP)
        5. 8.2.2.5  Choose the Output Capacitor
        6. 8.2.2.6  Choose the Input Capacitors (CIN)
        7. 8.2.2.7  Soft Start Capacitor (SS/REFIN Pin)
        8. 8.2.2.8  EN Pin Resistor Divider
        9. 8.2.2.9  VCC Bypass Capacitor
        10. 8.2.2.10 BOOT Capacitor
        11. 8.2.2.11 PGOOD Pullup Resistor
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Performance On TI EVM
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.3 Output Voltage Setting

The output voltage is programmed by the voltage-divider resistors, RFB_HS and RFB_LS. Connect RFB_HS between the FB pin and the positive node of the load, and connect RFB_LS between the FB pin and VSNS– pin. The recommended RFB_LS value is 10 kΩ, ranging from 1 kΩ to 20 kΩ. Determine RFB_HS by using Equation 1.

Equation 1. GUID-9132D9B5-5AF3-4F9C-A5F4-ED139C351BC1-low.gif

The FB accuracy is determined by two elements. The first element is the accuracy of the internal 600-mV reference, which will be applied to the SS/REFIN pin unless an external VREF is applied. The TPS548B28 device offers ±0.5% VINTREF accuracy from a 0°C to 85°C temperature range, and ±1.0% VINTREF accuracy from –40°C to 125°C temperature range. The second element is the SS/REFIN-to-FB accuracy which tells how accurately the control loop regulates FB node to SS/REFIN pin. The TPS548B28 device offers ±0.6% SS/REFIN-to-FB accuracy from –40°C to 125°C temperature range. For example, when operating from a 0°C to 85°C temperature range, the total FB accuracy is ±1.1% which includes the impact from chip junction temperature and also the variation from part to part.

To improve the overall VOUT accuracy, using a ±1% accuracy or better resistor for the FB voltage divider is highly recommended.

Regardless of remote sensing or single-end sensing connection, the FB voltage divider, RFB_HS and RFB_LS, must be always placed as close as possible to the device.