SLVSGM3B March   2023  – January 2024 TPS56836 , TPS56837 , TPS56838

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  The Adaptive On-Time Control and PWM Operation
      2. 6.3.2  Mode Selection
      3. 6.3.3  Soft Start and Pre-Biased Soft Start
      4. 6.3.4  Enable and Adjusting Undervoltage Lockout
      5. 6.3.5  Output Overcurrent Limit and Undervoltage Protection
      6. 6.3.6  Overvoltage Protection
      7. 6.3.7  UVLO Protection
      8. 6.3.8  Thermal Shutdown
      9. 6.3.9  Output Voltage Discharge
      10. 6.3.10 Power Good
      11. 6.3.11 Large Duty Operation
    4. 6.4 Device Functional Modes
      1. 6.4.1 Standby Operation
      2. 6.4.2 Eco-mode
      3. 6.4.3 Forced Continuous Conduction Mode
      4. 6.4.4 Out-of-Audio™ Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Custom Design With WEBENCH® Tools
        2. 7.2.2.2 Output Voltage Resistors Selection
        3. 7.2.2.3 Output Filter Selection
        4. 7.2.2.4 Input Capacitor Selection
        5. 7.2.2.5 Bootstrap Capacitor Selection
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.5 Output Overcurrent Limit and Undervoltage Protection

The output overcurrent protection (OCP) is implemented using a cycle-by-cycle low-side MOSFET valley current detection and high-side MOSFET peak current detection. The switching current is monitored by measuring the MOSFET drain to source voltage. This voltage is proportional to the switching current. To improve accuracy, the voltage sensing is temperature compensated.

There are some important considerations for this type of overcurrent limit. When the load current is higher than the ILS_OCL added by one half of the peak-to-peak inductor ripple current, or higher than IHS_OCL subtracted by one half of the peak-to-peak inductor ripple current, the OCP is triggered and the current is being limited. Output voltage tends to drop because the load demand is higher than what the converter can support. When the output voltage falls below 65% of the target voltage, the UVP comparator detects it and shuts down the device after a deglitch wait time of 256us and then re-start after the hiccup time of 10.5 cycles of soft-start time. When the overcurrent condition is removed, the output recovers.