JAJSNB5B July   2023  – June 2024 TPSM828301 , TPSM828302 , TPSM828303

PRODMIX  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Options
  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 RDS Package
    5. 6.5 Thermal Information VCB Package
    6. 6.6 Electrical 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 Pulse Width Modulation (PWM) Operation
      2. 7.3.2 Power Save Mode (PSM) Operation
      3. 7.3.3 Start-Up and Soft Start
      4. 7.3.4 Switch Cycle-by-Cycle Current Limit
      5. 7.3.5 Undervoltage Lockout
      6. 7.3.6 Thermal Shutdown
      7. 7.3.7 Optimized EMI Performance
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable, Disable, and Output Discharge
      2. 7.4.2 Minimum Duty Cycle and 100% Mode Operation
      3. 7.4.3 Power Good
  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 Setting The Output Voltage
        3. 8.2.2.3 Input Capacitor Selection
        4. 8.2.2.4 Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Thermal Considerations
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 サード・パーティ製品に関する免責事項
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 サポート・リソース
    4. 9.4 Trademarks
    5. 9.5 静電気放電に関する注意事項
    6. 9.6 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.3 Input Capacitor Selection

The input capacitor is the low-impedance energy source for the converter, which helps provide stable operation. Because the buck converter has a pulsating input current, a low ESR ceramic input capacitor is required for best input voltage filtering to minimize input voltage spikes. Place the capacitor between VIN and GND pins and as close as possible to those pins.

For most applications, a minimum effective input capacitance of 3 µF is sufficient, though a larger value reduces input current ripple and is recommended. When operating from a high impedance source, TI recommends a larger input buffer capacitor ≥10 µF to avoid voltage drops during start-up and load transients. Additionally, small de-coupling capacitors can also be used in case of noise at the input if the device. The input capacitor can be increased without any limit for better input voltage filtering.

Table 8-4 shows a list of recommended capacitors.

Table 8-3 List of Recommended Capacitors
NOMINAL CAPACITANCE [µF] VOLTAGE RATING [V] DIMENSIONS [mm] MFR PART NUMBER(1)
4.7 6.3 1.6 × 0.8 × 0.8 MSASJ168BB7475MTNA01, Taiyo Yuden
4.7 10 2.0 × 1.25 × 1.25 C2012X7R1A475K125AC, TDK
10 10 1.6 × 0.8 × 0.8 GRM188Z71A106KA73#, MuRata