SLVS675E August   2006  – January 2024 TPS5410

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  Oscillator Frequency
      2. 6.3.2  Voltage Reference
      3. 6.3.3  Enable (ENA) and Internal Slow-Start
      4. 6.3.4  Undervoltage Lockout (UVLO)
      5. 6.3.5  Boost Capacitor (BOOT)
      6. 6.3.6  Output Feedback (VSENSE)
      7. 6.3.7  Internal Compensation
      8. 6.3.8  Voltage Feed-Forward
      9. 6.3.9  Pulse-Width-Modulation (PWM) Control
      10. 6.3.10 Overcurrent Limiting
      11. 6.3.11 Overvoltage Protection
      12. 6.3.12 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Minimum Input Voltage
      2. 6.4.2 ENA Control
  8. 7 Applications and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Application Circuit
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Switching Frequency
          2. 7.2.1.2.2 Input Capacitors
          3. 7.2.1.2.3 Output Filter Components
            1. 7.2.1.2.3.1 Inductor Selection
            2. 7.2.1.2.3.2 Capacitor Selection
          4. 7.2.1.2.4 Output Voltage Setpoint
          5. 7.2.1.2.5 Boot Capacitor
          6. 7.2.1.2.6 Catch Diode
          7. 7.2.1.2.7 Advanced Information
            1. 7.2.1.2.7.1 Output Voltage Limitations
            2. 7.2.1.2.7.2 Internal Compensation Network
            3. 7.2.1.2.7.3 Thermal Calculations
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Using All Ceramic Capacitors
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
          1. 7.2.2.2.1 Output Filter Capacitor Selection
          2. 7.2.2.2.2 External Compensation Network
        3. 7.2.2.3 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 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
7.2.1.2.2 Input Capacitors

The TPS5410 requires an input decoupling capacitor and, depending on the application, a bulk input capacitor. The minimum recommended value for the decoupling capacitor is 4.7 μF. A high quality ceramic type X5R or X7R is required. For some applications, a smaller value decoupling capacitor can be used, if the input voltage and current ripple ratings are not exceeded. The voltage rating must be greater than the maximum input voltage, including ripple. For this design, a 4.7 μF capacitor, C1 issued to allow for smaller 1812 case size to be used while maintaining a 50-V rating.

This input ripple voltage can be approximated by Equation 2 :

Equation 2. GUID-A7321A89-BBE3-4FCC-886D-8DE9998CE368-low.gif

Where IOUT(MAX) is the maximum load current, fSW is the switching frequency, CI is the input capacitor value and ESRMAX is the maximum series resistance of the input capacitor.

The maximum RMS ripple current also must be checked. For worst case conditions, this is approximated by Equation 3:

Equation 3. GUID-9FEEBAD5-40CA-4CA3-A09A-8C5F353A2A62-low.gif

In this example, the calculated input ripple voltage is 137 mV, and the RMS ripple current is 0.5 A. The maximum voltage across the input capacitors is VIN max plus delta VIN/2. The chosen input decoupling capacitors are rated for 50 V, and the ripple current capacity for each is 3 A at 500 kHz, providing ample margin. The actual measured input ripple voltage can be larger than the calculated value due to the output impedance of the input voltage source, decrease in actual capacitance due to bias voltage and parasitics associated with the layout.

CAUTION:

The maximum ratings for voltage and current are not to be exceeded under any circumstance.

Additionally, some bulk capacitance can be needed, especially if the TPS5410 circuit is not located within approximately 2 inches from the input voltage source. The value for this capacitor is not critical but must be rated to handle the maximum input voltage including ripple voltage and must filter the output so that input ripple voltage is acceptable.