SLVS873F June   2015  – September 2021 TPS61098 , TPS610981 , TPS610982 , TPS610985 , TPS610986 , TPS610987

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Boost Controller Operation
      2. 8.3.2 Pass-Through Operation
      3. 8.3.3 LDO / Load Switch Operation
      4. 8.3.4 Start Up and Power Down
      5. 8.3.5 Over Load Protection
      6. 8.3.6 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation Modes by MODE Pin
        1. 8.4.1.1 Active Mode
        2. 8.4.1.2 Low Power Mode
      2. 8.4.2 Burst Mode Operation under Light Load Condition
      3. 8.4.3 Pass-Through Mode Operation
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 VMAIN to Power MCU and VSUB to Power Subsystem
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Device Choice
          2. 9.2.1.2.2 Maximum Output Current
          3. 9.2.1.2.3 Inductor Selection
          4. 9.2.1.2.4 Capacitor Selection
          5. 9.2.1.2.5 Control Sequence
        3. 9.2.1.3 Application Curves
      2. 9.2.2 VMAIN to Power the System in Low Power Mode
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 VSUB to Power the System in Active Mode
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  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 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.4 Start Up and Power Down

The boost converter of the TPS61098x is designed always-on, so there is no enable or disable control of it. The boost converter starts operation once input voltage is applied. If the input voltage is not high enough, a low voltage startup oscillator operates the switches first. During this phase, the switching frequency is controlled by the oscillator, and the maximum switch current is limited. Once the converter has built up the output voltage V(MAIN) to approximately 1.8 V, the device switches to the normal hysteretic current mode operation and the VMAIN rail starts to supply the internal control circuit. If the input voltage is too low or the load during startup is too heavy, which makes the converter unable to build up 1.8 V at V(MAIN) rail, the boost converter can't start up successfully. It will keep in this status until the input voltage is increased or removed.

The TPS61098x is able to startup with 0.7 V input voltage with ≥ 3 kΩ load. The startup time depends on input voltage and load conditions. After the V(MAIN) reaches 1.8 V to start the normal hysteretic current mode operation, an internal ramp-up reference controls soft-start time of the boost converter until V(MAIN) reaches its set value.

The TPS61098x does not support undervoltage lockout function. When the input voltage drops to a low voltage and can't provide the required energy to the boost converter, the V(MAIN) drops. When and to what extent V(MAIN) drops are dependent on the input and load conditions. When the boost converter is unable to maintain 1.8 V at VMAIN rail to supply the internal circuit, the TPS61098x powers down and enters into startup process again.