SNVSCB1C December   2022  – February 2024 TPSM33615 , TPSM33625

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  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 System Characteristics
    7. 6.7 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  Input Voltage Range
      2. 7.3.2  Output Voltage Selection
      3. 7.3.3  Input Capacitors
      4. 7.3.4  Output Capacitors
      5. 7.3.5  Enable, Start-Up, and Shutdown
      6. 7.3.6  External CLK SYNC (with MODE/SYNC)
        1. 7.3.6.1 Pulse-Dependent MODE/SYNC Pin Control
      7. 7.3.7  Switching Frequency (RT)
      8. 7.3.8  Power-Good Output Operation
      9. 7.3.9  Internal LDO, VCC and VOUT/FB Input
      10. 7.3.10 Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
      11. 7.3.11 Spread Spectrum
      12. 7.3.12 Soft Start and Recovery from Dropout
        1. 7.3.12.1 Recovery from Dropout
      13. 7.3.13 Overcurrent Protection (Hiccup Mode)
      14. 7.3.14 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
        1. 7.4.3.1 CCM Mode
        2. 7.4.3.2 Auto Mode – Light-Load Operation
          1. 7.4.3.2.1 Diode Emulation
          2. 7.4.3.2.2 Frequency Reduction
        3. 7.4.3.3 FPWM Mode – Light-Load Operation
        4. 7.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 7.4.3.5 Dropout
  9. 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  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Choosing the Switching Frequency
        3. 8.2.2.3  Setting the Output Voltage
        4. 8.2.2.4  Input Capacitor Selection
        5. 8.2.2.5  Output Capacitor Selection
        6. 8.2.2.6  VCC
        7. 8.2.2.7  CFF Selection
        8. 8.2.2.8  Power Good Signal
        9. 8.2.2.9  Maximum Ambient Temperature
        10. 8.2.2.10 Other Connections
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Ground and Thermal Considerations
      2. 8.5.2 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
      3. 9.1.3 Device Nomenclature
    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. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.11 Spread Spectrum

Spread spectrum eliminates peak emissions at specific frequencies by spreading these peaks across a wider range of frequencies than a part with fixed-frequency operation. The TPSM336x5 implements a modulation pattern designed to reduce low frequency-conducted emissions from the first few harmonics of the switching frequency. The pattern can also help reduce the higher harmonics that are more difficult to filter, which can fall in the FM band. These harmonics often couple to the environment through electric fields around the switch node and inductor. The TPSM336x5 uses a ±4% spread of frequencies which can spread energy smoothly across the FM and TV bands. The device implements dual random spread spectrum (DRSS). DRSS is a combination of a triangular frequency spreading pattern and pseudorandom frequency hopping. The combination allows the spread spectrum to be very effective at spreading the energy at the following:

  • Fundamental switching harmonic with slow triangular pattern
  • High frequency harmonics with additional pseudo-random jumps at the switching frequency

The advantage of DRSS is its equivalent harmonic attenuation in the upper frequencies with a smaller fundamental frequency deviation. This advantage reduces the amount of input current and output voltage ripple that is introduced at the modulating frequency. Additionally, the TPSM336x5 also allows the user to further reduce the output voltage ripple caused by the spread spectrum modulating pattern.

The spread spectrum is only available while the clock of the device is free running at its natural frequency. Any of the following conditions overrides spread spectrum, turning it off:

  • The clock is slowed due to operation at low-input voltage – this is operation in dropout.
  • The clock is slowed under light load in auto mode. Note that if you are operating in FPWM mode, spread spectrum can be active, even if there is no load.
  • The clock is slowed due to high input to output voltage ratio. This mode of operation is expected if on time reaches minimum on time. See the Electrical Characteristics.
  • The clock is synchronized with an external clock.