JAJS012J October   2004  – November 2018 TPS75003

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      代表的なアプリケーションの回路図
  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 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
      1. 6.6.1 Buck Converter
      2. 6.6.2 LDO Converter
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Operation (Buck Controllers)
      2. 7.3.2  Enable (Buck Controllers)
      3. 7.3.3  UVLO (Buck Controllers)
      4. 7.3.4  Current Limit (Buck Controllers)
      5. 7.3.5  Short-Circuit Protection (Buck Controllers)
      6. 7.3.6  Soft-Start (Buck Controllers)
      7. 7.3.7  LDO Operation
      8. 7.3.8  Internal Current Limit (LDO)
      9. 7.3.9  Enable Pin (LDO)
      10. 7.3.10 Dropout Voltage (LDO)
      11. 7.3.11 Transient Response (LDO)
      12. 7.3.12 Thermal Protection (LDO)
      13. 7.3.13 Power Dissipation (LDO)
  8. 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  Input Capacitor CIN1, CIN2 Selection (Buck Controllers)
        2. 8.2.2.2  Inductor Value Selection (Buck Controllers)
        3. 8.2.2.3  External PMOS Transistor Selection (Buck Controllers)
        4. 8.2.2.4  Diode Selection (Buck Controllers)
        5. 8.2.2.5  Output Capacitor Selection (Buck Controllers)
        6. 8.2.2.6  Output Voltage Ripple Effect on VOUT (Buck Controllers)
        7. 8.2.2.7  Soft-Start Capacitor Selection (Buck Controllers)
        8. 8.2.2.8  Output Voltage Setting Selection (Buck Controllers)
        9. 8.2.2.9  Input Capacitor Selection (LDO)
        10. 8.2.2.10 Output Capacitor Selection (LDO)
        11. 8.2.2.11 Soft-Start Capacitor Selection (LDO)
        12. 8.2.2.12 Setting Output Voltage (LDO)
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 PCB Layout Considerations
    2. 10.2 Layout Example
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 11.1.2 開発サポート
    2. 11.2 ドキュメントのサポート
      1. 11.2.1 関連資料
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 コミュニティ・リソース
    5. 11.5 商標
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 Glossary
  12. 12メカニカル、パッケージ、および注文情報

8.2.2.2 Inductor Value Selection (Buck Controllers)

The inductor is chosen based on inductance value and maximum current rating. Larger inductors reduce current ripple (and therefore, output voltage ripple) but are physically larger and more expensive. Inductors with lower DC resistance typically improve efficiency, but also have higher cost and larger physical size. The buck converters work well with inductor values between 4.7μH and 47μH in most applications. When selecting an inductor, the current rating should exceed the current limit set by RIS or RDS,ON (see the Current Limit (Buck Controllers) section). To determine the minimum inductor size, first determine if the device will operate in minimum on-time or minimum off-time mode. The device will operate in minimum on-time mode if Equation 6 is satisfied:

Equation 6. TPS75003 q_VI_VO_IO_bvs052.gif

where

  • RL = the inductor DC resistance

Minimum inductor size needed when operating in minimum on-time mode is given by Equation 7:

Equation 7. TPS75003 q_Lmin1_bvs052.gif

Minimum inductor size needed when operating in minimum off-time mode is given by Equation 8:

Equation 8. TPS75003 q_Lmin2_bvs052_.gif

where

  • ΔIL = (20%–30%) × IOUT-MAX