SLVSDX7D January   2019  – July 2021 TPS61022

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 Undervoltage Lockout
      2. 7.3.2 Enable and Soft Start
      3. 7.3.3 Switching Frequency
      4. 7.3.4 Current Limit Operation
      5. 7.3.5 Pass-Through Operation
      6. 7.3.6 Overvoltage Protection
      7. 7.3.7 Output Short-to-Ground Protection
      8. 7.3.8 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forced PWM Mode
      2. 7.4.2 Power-Save Mode
  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 Setting the Output Voltage
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Loop Stability, Feedforward Capacitor Selection
        5. 8.2.2.5 Input Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    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
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.4 Current Limit Operation

The TPS61022 uses a valley current limit sensing scheme. Current limit detection occurs during the off-time by sensing of the voltage drop across the synchronous rectifier.

When the load current is increased such that the inductor current is above the current limit within the whole switching cycle time, the off-time is increased to allow the inductor current to decrease to this threshold before the next on-time begins (so called frequency fold-back mechanism). When the current limit is reached, the output voltage decreases during further load increase.

The maximum continuous output current (IOUT(LC)), before entering current limit (CL) operation, can be defined by Equation 1.

Equation 1. GUID-D4E0E0C1-C5F4-4F08-81CE-59F5475273D2-low.gif

where

  • D is the duty cycle
  • ΔIL(P-P) is the inductor ripple current

The duty cycle can be estimated by Equation 2.

Equation 2. GUID-0A3741E4-AF3C-4507-88A9-B120EBE13566-low.gif

where

  • VOUT is the output voltage of the boost converter
  • VIN is the input voltage of the boost converter
  • η is the efficiency of the converter, use 90% for most applications

The peak-to-peak inductor ripple current is calculated by Equation 3.

Equation 3. GUID-57E23298-4B83-47BF-9BC9-EEBE023F6B02-low.gif

where

  • L is the inductance value of the inductor
  • fSW is the switching frequency
  • D is the duty cycle
  • VIN is the input voltage of the boost converter