SLVSGJ4C October   2022  – July 2023 TPSM82912 , TPSM82913 , TPSM82913E

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Smart Config (S-CONF)
      2. 7.3.2  Device Enable (EN/SYNC)
      3. 7.3.3  Device Synchronization (EN/SYNC)
      4. 7.3.4  Spread Spectrum Modulation
      5. 7.3.5  Output Discharge
      6. 7.3.6  Undervoltage Lockout (UVLO)
      7. 7.3.7  Power-Good Output
      8. 7.3.8  Noise Reduction and Soft-Start Capacitor (NR/SS)
      9. 7.3.9  Current Limit and Short-Circuit Protection
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Fixed Frequency Pulse Width Modulation
      2. 7.4.2 Low Duty Cycle Operation
      3. 7.4.3 High Duty Cycle Operation (100% Duty Cycle)
      4. 7.4.4 Second Stage L-C Filter Compensation (Optional)
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 External Component Selection
          1. 8.2.2.2.1 Switching Frequency Selection
          2. 8.2.2.2.2 Output Capacitor Selection
          3. 8.2.2.2.3 Ferrite Bead Selection for Second L-C Filter
          4. 8.2.2.2.4 Input Capacitor Selection
          5. 8.2.2.2.5 Setting the Output Voltage
          6. 8.2.2.2.6 NR/SS Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Tape and Reel Information

Package Options

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

7.3.9 Current Limit and Short-Circuit Protection

The device is protected against short circuits and overcurrent. The switch current limit prevents the device from high inductor current and from drawing excessive current from the input voltage rail. Excessive current can occur with a shorted, saturated inductor or a heavy load, shorted output circuit condition. If the inductor current reaches the threshold ISWpeak, the high-side MOSFET is turned off and the low-side MOSFET is turned on to ramp down the inductor current. The high-side MOSFET is turned on again only when the low-side current is below the low-side sourcing current limit ISWvalley.

Due to internal propagation delay, the actual current can exceed the static current limit, especially if the input voltage is high and very small inductances are used. The dynamic current limit is calculated as follows:

Equation 1. TPSM82912 TPSM82913 TPSM82913E

where

  • ISWpeak is the static current limit, specified in Electrical Characteristics
  • L is the inductance (2.2 μH for the TPSM8291x)
  • VL is the voltage across the inductor (VIN – VOUT)
  • tPD is the internal propagation delay, typically 50 ns

The low-side MOSFET also contains a negative current limit to prevent excessive current from flowing back through the inductor to the input. This can happen during light load conditions or a pre-biased output condition. If the low-side sinking current limit is exceeded, the low-side MOSFET is turned off. In this scenario, both MOSFETs are off until the start of the next cycle.