SLVSFP4B August   2020  – March 2021 TPS62912 , TPS62913

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  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)
  8. 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 Inductor Selection for the First L-C Filter
          3. 8.2.2.2.3 Output Capacitor Selection
          4. 8.2.2.2.4 Ferrite Bead Selection for Second L-C Filter
          5. 8.2.2.2.5 Input Capacitor Selection
          6. 8.2.2.2.6 Setting the Output Voltage
          7. 8.2.2.2.7 NR/SS 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
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.4 Spread Spectrum Modulation

Using the S-CONF pin enables or disables spread spectrum modulation. DC/DC converters generate an output voltage ripple at the switching frequency. When powering ADCs or an analog front end (AFE), the switching frequency generates high frequency mixing spurs as well as a low frequency spur in the output frequency spectrum. Using the optional second stage L-C filter reduces the ripple of the converter and spurs by up to 30 dB.

The device has integrated two different spread spectrum modulation (SSM) schemes that are selected by the resistor connected to the S-CONF pin acording to Table 7-1. It is possible to select random or triangle modulation to spread the switching frequency over a larger frequency range. The triangular SSM is modulated based on the switching frequency, and results in 1.9 kHz for 1 MHz switching frequency and 4.3 kHz for 2.2 MHz switching frequency. The modulation spread is ±10% of the device switching frequency. This SSM provides high attenuation when the receiver bandwidth is less than the modulation frequency, typically the case for systems using Fast Fourier Transforms (FFT) post processing as in high speed ADC applications. For applications sensitive to noise at the modulation frequency, random SSM is used. Using a random spread spectrum modulation also reduces the spurs in the output spectrum as shown in Figure 6-2. The random SSM operates with the same frequency spread and modulation period as the triangular SSM. The randomized modulation uses a Fibonacci Linear-Feedback Shift Register (LFSR) so that every tone is generated once during the pseudo-random generation period. The frequency spreading is shown in Figure 7-2.The attenuation using random or triangle SSM is shown in Figure 6-28.

GUID-20200730-CA0I-DFXK-6BZ8-CS7NN0R90RCS-low.gif Figure 7-2 Spread Spectrum Modulation