JAJSBJ7H June   2009  – September 2016 LM5009A

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 改訂履歴
  5. 5 Pin Configuration and 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 Switching Characteristics
    7. 6.7 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 Control Circuit Overview
      2. 7.3.2 Start-Up Regulator (VCC)
      3. 7.3.3 Regulation Comparator
      4. 7.3.4 Overvoltage Comparator
      5. 7.3.5 ON-Time Generator and Shutdown
      6. 7.3.6 Current Limit
      7. 7.3.7 N-Channel Buck Switch and Driver
      8. 7.3.8 Thermal Protection
    4. 7.4 Device Functional Modes
  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  RFB1 and RFB2
        2. 8.2.2.2  Fs and RT
        3. 8.2.2.3  L1
          1. 8.2.2.3.1 Minimum Load Current
          2. 8.2.2.3.2 Maximum Load Current
        4. 8.2.2.4  C3
        5. 8.2.2.5  C2 and R3
        6. 8.2.2.6  ESR and R3
        7. 8.2.2.7  C2
        8. 8.2.2.8  RCL
        9. 8.2.2.9  D1
        10. 8.2.2.10 C1
        11. 8.2.2.11 C4
        12. 8.2.2.12 C5
        13. 8.2.2.13 Ripple Configuration
      3. 8.2.3 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 ドキュメントのサポート
      1. 11.1.1 関連資料
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 コミュニティ・リソース
    4. 11.4 商標
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 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

10 Layout

10.1 Layout Guidelines

The LM5009A regulation and overvoltage comparators are very fast, and as such respond to short duration noise pulses. Therefore, layout considerations are critical for optimum performance. The components at pins 1, 2, 3, 5, and 6 must be as physically close as possible to the IC, thereby minimizing noise pickup in the PC tracks. The current loop formed by D1, L1, and C2 must be as small as possible. The ground connection from D1 to C1 must be as short and direct as possible.

If the internal dissipation of the LM5009A produces excessive junction temperatures during normal operation, good use of the PCB ground plane can help to dissipate heat. The exposed pad on the bottom of the 8-pin WSON package is soldered to a ground plane on the PCB, and that plane must extend out from beneath the IC to help dissipate the heat. Additionally, the use of wide PCB traces, where possible, can also help conduct heat away from the IC. Judicious positioning of the PCB within the end product, along with use of any available air flow (forced or natural convection) can help reduce the junction temperatures.

10.2 Layout Example

LM5009A LM5009A_LAYOUTEX.gif Figure 13. LM5009A Buck Layout Example With the WSON Package