JAJSHM1B July   2008  – June 2019 TPS5450-Q1

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図と効率曲線
  4. 4 改訂履歴
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Recommended Operating Conditions
    3. 6.3 Thermal Information
    4. 6.4 Dissipation Ratings
    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  Oscillator Frequency
      2. 7.3.2  Voltage Reference
      3. 7.3.3  Enable (ENA) and Internal Slow Start
      4. 7.3.4  Undervoltage Lockout (UVLO)
      5. 7.3.5  Output Feedback (VSENSE) and Internal Compensation
      6. 7.3.6  Voltage Feedforward
      7. 7.3.7  Pulse-Width-Modulation (PWM) Control
      8. 7.3.8  Overcurrent Limiting
      9. 7.3.9  Overvoltage Protection
      10. 7.3.10 Thermal Shutdown
  8. 8 Application Information
    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  Boost Capacitor (BOOT)
        3. 8.2.2.3  Switching Frequency
        4. 8.2.2.4  Input Capacitors
        5. 8.2.2.5  Output Filter Components
          1. 8.2.2.5.1 Inductor Selection
          2. 8.2.2.5.2 Capacitor Selection
        6. 8.2.2.6  Output Voltage Setpoint
        7. 8.2.2.7  Boot Capacitor
        8. 8.2.2.8  Catch Diode
        9. 8.2.2.9  Output Voltage Limitations
        10. 8.2.2.10 Internal Compensation Network
      3. 8.2.3 Application Curves
  9. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Examples
    3. 9.3 Thermal Calculations
  10. 10デバイスおよびドキュメントのサポート
    1. 10.1 デバイス・サポート
      1. 10.1.1 デベロッパー・ネットワークの製品に関する免責事項
    2. 10.2 開発サポート
      1. 10.2.1 WEBENCH®ツールによるカスタム設計
    3. 10.3 ドキュメントの更新通知を受け取る方法
    4. 10.4 コミュニティ・リソース
    5. 10.5 商標
    6. 10.6 静電気放電に関する注意事項
    7. 10.7 Glossary
  11. 11メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.2.2.5.1 Inductor Selection

To calculate the minimum value of the output inductor, use Equation 4:

Equation 4. TPS5450-Q1 q_lmin_lvs757.gif

KIND is a coefficient that represents the amount of inductor ripple current relative to the maximum output current. Three things need to be considered when determining the amount of ripple current in the inductor: the peak-to-peak ripple current affects the output ripple voltage amplitude, the ripple current affects the peak switch current, and the amount of ripple current determines at what point the circuit becomes discontinuous. For designs using the TPS5450-Q1, KIND of 0.2 to 0.3 yields good results. Low output ripple voltages can be obtained when paired with the proper output capacitor, the peak switch current will be well below the current limit set point, and relatively low load currents can be sourced before discontinuous operation.

For this design example use KIND = 0.2 and the minimum inductor value is calculated to be 10.4 μH. A higher standard value is 15 μH, which is used in this design.

For the output filter inductor it is important that the RMS current and saturation current ratings not be exceeded. The RMS inductor current can be found from Equation 5:

Equation 5. TPS5450-Q1 q_ilrms_lvs757.gif

and the peak inductor current can be determined with Equation 6:

Equation 6. TPS5450-Q1 q_ilpk_lvs757.gif

For this design, the RMS inductor current is 5.004 A, and the peak inductor current is 5.34 A. The chosen inductor is a Sumida CDRH1127/LD-150 15 μH. It has a minimum rated current of 5.65 A for both saturation and RMS current. In general, inductor values for use with the TPS5450-Q1 are in the range of 10 μH to 100 μH.