SLUSDA4B February   2019  – October 2019 TPS562231

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      TPS562231 Efficiency
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Adaptive On-Time Control and PWM Operation
      2. 7.3.2 Soft Start and Pre-Biased Soft Start
      3. 7.3.3 Over Current and Short Circuit Protection
      4. 7.3.4 Undervoltage Lockout (UVLO) Protection
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Continuous Conduction Mode (CCM)
      3. 7.4.3 Pulse Skip Mode (PSM, TPS562231)
  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 Resistors Selection
        2. 8.2.2.2 Output Filter Selection
        3. 8.2.2.3 Input Capacitor Selection
        4. 8.2.2.4 Bootstrap Capacitor Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.3 Over Current and Short Circuit Protection

The TPS562231 is protected from over-current conditions by cycle-by-cycle current limit on the valley of the inductor current. Hiccup mode will be activated if a fault condition persists to prevent over-heating.

The current going through low-side (LS) MOSFET is sensed and monitored. When the LS MOSFET turns on, the inductor current begins to ramp down. The LS MOSFET will not be turned OFF if its current is above the LS current limit ILS_LIMIT even the feedback voltage, VFB, drops below the reference voltage VREF. The LS MOSFET is kept ON so that inductor current keeps ramping down, until the inductor current ramps below the LS current limit ILS_LIMIT. Then the LS MOSFET is turned OFF and the HS switch is turned on after a dead time.

As the inductor current is limited by ILS_LIMT, the output voltage tends to drop as the inductor current may be smaller than the load current. Hiccup current protection mode is activated once the VFB drops below the UVP threshold after a delay time (600 µs typically). In hiccup mode, the regulator is shut down and kept off for 24 ms typically before the TPS562231 try to start again. If over-current or short-circuit fault condition still exist, hiccup will repeat until the fault condition is removed. Hiccup mode reduces power dissipation under severe over-current conditions, prevents over-heating and potential damage to the device.