SLVSFS3B September   2020  – July 2021 TPS62868 , TPS62869

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Options
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 I2C InterfaceTiming Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Power Save Mode
      2. 8.3.2 Forced PWM Mode
      3. 8.3.3 100% Duty Cycle Mode Operation
      4. 8.3.4 Start-up
      5. 8.3.5 Switch Current Limit and HICCUP Short-Circuit Protection
      6. 8.3.6 Undervoltage Lockout (UVLO)
      7. 8.3.7 Thermal Warning and Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Enable and Disable (EN)
      2. 8.4.2 Output Discharge
      3. 8.4.3 Start-Up Output Voltage and I2C Target Address Selection
        1. 8.4.3.1 TPS6286xxA Devices
        2. 8.4.3.2 TPS6286xxxC Devices
      4. 8.4.4 Select Output Voltage Registers (VID)
      5. 8.4.5 Power Good ( PG)
    5. 8.5 Programming
      1. 8.5.1 Serial Interface Description
      2. 8.5.2 Standard-, Fast-, and Fast-Mode Plus Protocol
      3. 8.5.3 HS-Mode Protocol
      4. 8.5.4 I2C Update Sequence
      5. 8.5.5 I2C Register Reset
    6. 8.6 Register Map
      1. 8.6.1 Target Address Byte
      2. 8.6.2 Register Address Byte
      3. 8.6.3 VOUT Register 1
      4. 8.6.4 VOUT Register 2
      5. 8.6.5 CONTROL Register
      6. 8.6.6 STATUS Register
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Setting The Output Voltage
        2. 9.2.2.2 Output Filter Design
        3. 9.2.2.3 Inductor Selection
        4. 9.2.2.4 Capacitor Selection
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application – TPS6286x0A and TPS6286x0xC Devices
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
        1. 9.3.2.1 Setting the Output Voltage
        2. 9.3.2.2 Output Filter Design
        3. 9.3.2.3 Inductor Selection
        4. 9.3.2.4 Capacitor Selection
      3. 9.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
      1. 11.2.1 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Support Resources
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Trademarks
    6. 12.6 Glossary
    7. 12.7 Electrostatic Discharge Caution
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.3 100% Duty Cycle Mode Operation

There is no limitation for small duty cycles since even at very low duty cycles, the switching frequency is reduced as needed to always ensure a proper regulation.

If the output voltage level comes close to the input voltage, the device enters 100% mode. While the high-side switch is constantly turned on, the low-side switch is switched off. The difference between VIN and VOUT is determined by the voltage drop across the high-side MOSFET and the DC resistance of the inductor. The minimum VIN that is needed to maintain a specific VOUT value is estimated as:

Equation 2.

where

  • VIN,MIN is the minimum input voltage to maintain an output voltage
  • IOUT,MAX is the maximum output current
  • RDS(on) is the high-side FET ON-resistance
  • RL is the inductor ohmic resistance (DCR)