SLVSHM4A December   2023  – June 2024 TPS62916E

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  Smart Config (S-CONF)
      2. 6.3.2  Device Enable (EN/SYNC)
      3. 6.3.3  Device Synchronization (EN/SYNC)
      4. 6.3.4  Spread Spectrum Modulation
      5. 6.3.5  Output Discharge
      6. 6.3.6  Undervoltage Lockout (UVLO)
      7. 6.3.7  Power-Good Output
      8. 6.3.8  Noise Reduction and Soft-Start Capacitor (NR/SS)
      9. 6.3.9  Current Limit and Short-Circuit Protection
      10. 6.3.10 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Fixed Frequency Pulse Width Modulation
      2. 6.4.2 Low Duty Cycle Operation
      3. 6.4.3 High Duty Cycle Operation (100% Duty Cycle)
      4. 6.4.4 Second Stage L-C Filter Compensation (Optional)
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      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 External Component Selection
          1. 7.2.2.2.1 Switching Frequency Selection
          2. 7.2.2.2.2 Inductor Selection for the First L-C Filter
          3. 7.2.2.2.3 Output Capacitor Selection
          4. 7.2.2.2.4 Ferrite Bead Selection for Second L-C Filter
          5. 7.2.2.2.5 Input Capacitor Selection
          6. 7.2.2.2.6 Setting the Output Voltage
          7. 7.2.2.2.7 NR/SS 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 Third-Party Products Disclaimer
      2. 8.1.2 Development Support
        1. 8.1.2.1 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

6.3.8 Noise Reduction and Soft-Start Capacitor (NR/SS)

A capacitor connected to this pin reduces the low frequency noise of the converter and sets the soft-start time. The larger the capacitor, the lower the noise and the longer the start-up time of the converter. A 470 nF capacitor is typically connected to this pin for a start-up time of 5 ms, although longer and shorter start-up times can be used. During soft start with a light load, the device skips switching pulses as needed to not discharge the output voltage. The device can start into a prebiased output voltage.

The device achieves low noise by adding an R-C filter to the reference voltage, as shown in Section 6.2. During start-up, the NR/SS capacitor is charged with a constant current of 75 µA (typical) to 0.8 V. Larger NR/SS capacitors provide for lower low frequency noise. The maximum NR/SS cap is 3.3 µF for a start-up time of 35 ms. The minimum start-up time is set internally to 0.7 ms, which occurs when there is a small NR/SS capacitor or no NR/SS capacitor.