JAJS463D NOVEMBER   2009  – March 2018 TPS40303 , TPS40304 , TPS40305

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      アプリケーション概略図
  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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Voltage Reference
      2. 7.3.2 Enable Functionality, Start-Up Sequence and Timing
      3. 7.3.3 Soft-Start Time
      4. 7.3.4 Oscillator and Frequency Spread Spectrum (FSS)
      5. 7.3.5 Overcurrent Protection
      6. 7.3.6 Drivers
      7. 7.3.7 Prebias Start-Up
      8. 7.3.8 Power Good
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
        1. 7.4.1.1 UVLO
        2. 7.4.1.2 Disable
        3. 7.4.1.3 Calibration
        4. 7.4.1.4 Converting
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Using the TPS40305 for a 12-V to 1.8-V Point-of-Load Synchronous Buck Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2  Selecting the Switching Frequency
          3. 8.2.1.2.3  Inductor Selection (L1)
          4. 8.2.1.2.4  Output Capacitor Selection (C12)
          5. 8.2.1.2.5  Peak Current Rating of Inductor
          6. 8.2.1.2.6  Input Capacitor Selection (C8)
          7. 8.2.1.2.7  MOSFET Switch Selection (Q1 and Q2)
          8. 8.2.1.2.8  Bootstrap Capacitor (C6)
          9. 8.2.1.2.9  VDD Bypass Capacitor (C7)
          10. 8.2.1.2.10 BP Bypass Capacitor (C5)
          11. 8.2.1.2.11 Short-Circuit Protection (R11)
          12. 8.2.1.2.12 Feedback Divider (R4, R5)
          13. 8.2.1.2.13 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.1.3 Application Curves
      2. 8.2.2 A High-Current, Low-Voltage Design Using the TPS40304
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1  Selecting the Switching Frequency
          2. 8.2.2.2.2  Inductor Selection (L1)
          3. 8.2.2.2.3  Output Capacitor Selection (C12)
          4. 8.2.2.2.4  Peak Current Rating of Inductor
          5. 8.2.2.2.5  Input Capacitor Selection (C8)
          6. 8.2.2.2.6  MOSFET Switch Selection (Q1 and Q2)
          7. 8.2.2.2.7  Bootstrap Capacitor (C6)
          8. 8.2.2.2.8  VDD Bypass Capacitor (C7)
          9. 8.2.2.2.9  BP Bypass Capacitor (C5)
          10. 8.2.2.2.10 Short-Circuit Protection (R11)
          11. 8.2.2.2.11 Feedback Divider (R4, R5)
          12. 8.2.2.2.12 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.2.3 Application Curves
      3. 8.2.3 A Synchronous Buck Application Using the TPS40303
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1  Selecting the Switching Frequency
          2. 8.2.3.2.2  Inductor Selection (L1)
          3. 8.2.3.2.3  Output Capacitor Selection (C12)
          4. 8.2.3.2.4  Peak Current Rating of Inductor
          5. 8.2.3.2.5  Input Capacitor Selection (C8)
          6. 8.2.3.2.6  MOSFET Switch Selection (Q1 and Q2)
          7. 8.2.3.2.7  Bootstrap Capacitor (C6)
          8. 8.2.3.2.8  VDD Bypass Capacitor (C7)
          9. 8.2.3.2.9  BP Bypass Capacitor (C5)
          10. 8.2.3.2.10 Short-Circuit Protection (R11)
          11. 8.2.3.2.11 Feedback Divider (R4, R5)
          12. 8.2.3.2.12 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.3.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    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. 11.2 WEBENCH®ツールによるカスタム設計
    3. 11.3 ドキュメントのサポート
      1. 11.3.1 関連資料
    4. 11.4 関連リンク
    5. 11.5 ドキュメントの更新通知を受け取る方法
    6. 11.6 コミュニティ・リソース
    7. 11.7 商標
    8. 11.8 静電気放電に関する注意事項
    9. 11.9 Glossary
  12. 12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

8.2.1.2.11 Short-Circuit Protection (R11)

The TPS40305 uses the negative drop across the low-side FET at the end of the OFF time to measure the inductor current. Allowing for 30% over maximum load and 20% rise in RDS(on)Q1 for self-heating, the voltage drop across the low-side FET at current limit is given by Equation 16.

Equation 16. TPS40303 TPS40304 TPS40305 deq_voc_lus964.gif

The TPS40305 internal temperature coefficient helps compensate for the RDS(on) temperature coefficient of the MOSFET, so the current limit programming resistor is selected by Equation 17.

Equation 17. TPS40303 TPS40304 TPS40305 deq_rcs_lus964.gif