SNAS894B July   2025  – December 2025 LMR60460-Q1

PRODMIX  

  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 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 Enable and Undervoltage Lockout (UVLO)
      2. 7.3.2 Soft Start and Recovery from Dropout
      3. 7.3.3 Frequency Selection With RT
      4. 7.3.4 MODE/SYNC Pin Control
      5. 7.3.5 Output Voltage Selection
      6. 7.3.6 Current Limit
      7. 7.3.7 Hiccup Mode
      8. 7.3.8 Power-Good Function
      9. 7.3.9 Spread Spectrum
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown
      2. 7.4.2 Active Mode
        1. 7.4.2.1 Auto Mode Operation
        2. 7.4.2.2 Continuous Conduction Mode (CCM)
        3. 7.4.2.3 FPWM Operation
        4. 7.4.2.4 Minimum On-Time
        5. 7.4.2.5 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 Switching Frequency Selection
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Input Capacitor Selection
        5. 8.2.2.5 Bootstrap Capacitor (CBOOT) Selection
        6. 8.2.2.6 FB Voltage Divider for Adjustable Output Voltages
          1. 8.2.2.6.1 Feedforward Capacitor (CFF) Selection
        7. 8.2.2.7 RPG - PG Pullup Resistor
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Ground and Thermal Plane Considerations
      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 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
    1. 11.1 Tape and Reel Information

8.2.2.4 Input Capacitor Selection

Input capacitors serve two important functions: The first is to reduce input voltage ripple into the LMR60460-Q1 and the input filter of the system. The second is to reduce high frequency noise. These two functions are implemented most effectively with separate capacitors. The input capacitors must be rated for at least the maximum input voltage that the application requires; preferably twice the maximum input voltage. See the following table.

Table 8-3 Input Capacitor
CAPACITOR RECOMMENDED VALUE COMMENT
CIN_HF 0.1µF This capacitor is used to suppress high frequency noise originating during switching events. Place this capacitor as close to the LMR60460-Q1 devices as design rules allow. Position is more important than exact capacity. After high frequency propagates into a system, suppressing or filtering can be hard. Because this high-frequency input capacitor is exposed to battery voltage in systems that operate directly off of battery, TI recommends 50V or higher voltage rating with an X7R or better dielectric.
CIN 2 × 4.7µF This capacitance is used to suppress input ripple and transients due to output load transients. If CIN is too small, input voltage can dip during load transients resetting the system if the system is operated under low voltage conditions. TI recommends 2 × 4.7µF for 400kHz and 1 × 4.7µF for 2MHz ceramic capacitors adjacent to the input pins of LMR60460-Q1 devices. Because the input capacitors are exposed to battery voltage in systems that operate directly off of battery, TI recommends 50V or higher voltage rating with an X7R or better dielectric.

The values of CIN-HF and CIN presented in Table 8-3 can be used in most applications. If a certain amount of input voltage ripple is required, use Equation 11 to calculate the required input capacitance, but not less than recommended in the above table.

Equation 11. CIN≥D×1-D×IOUTΔVIN_PP×fsw

Where:

  • D = Duty cycle = VOUT / VIN
  • IOUT = DC output current
  • ΔVIN_PP = peak-to-peak input voltage ripple
  • fsw = switching frequency

Use Equation 12 to compare the RMS current rating of the selected input capacitors to make sure the input capacitors are capable of supplying the input switching current.

Equation 12. IIN_RMS_max⁡=IOUT×D×1-D+112×VOUTL×fsw×IOUT2×1-D2×D