JAJSG39 September   2018 LM2735-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.      代表的な昇圧アプリケーションの回路
      2.      効率と負荷電流との関係VO＝12V
  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
      1. 7.1.1 Theory of Operation
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Current Limit
      2. 7.3.2 Thermal Shutdown
      3. 7.3.3 Soft Start
      4. 7.3.4 Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Pin and Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1  LM2735X-Q1 SOT-23 Design Example 1
        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 Inductor Selection
          3. 8.2.1.2.3 Input Capacitor
          4. 8.2.1.2.4 Output Capacitor
          5. 8.2.1.2.5 Setting the Output Voltage
        3. 8.2.1.3 Application Curves
      2. 8.2.2  LM2735Y-Q1 SOT-23 Design Example 2
      3. 8.2.3  LM2735X-Q1 WSON Design Example 3
      4. 8.2.4  LM2735Y-Q1 WSON Design Example 4
      5. 8.2.5  LM2735X-Q1 SOT-23 Design Example 6
      6. 8.2.6  LM2735Y-Q1 SOT-23 Design Example 7
      7. 8.2.7  LM2735X-Q1 SOT-23 Design Example 8
      8. 8.2.8  LM2735Y-Q1 SOT-23 Design Example 9
      9. 8.2.9  LM2735X-Q1 WSON Design Example 10
      10. 8.2.10 LM2735Y-Q1 WSON Design Example 11
      11. 8.2.11 LM2735X-Q1 WSON SEPIC Design Example 12
      12. 8.2.12 LM2735X-Q1 SOT-23 LED Design Example 14
      13. 8.2.13 LM2735Y-Q1 WSON FlyBack Design Example 15
      14. 8.2.14 LM2735X-Q1 SOT-23 LED Design Example 16 VRAIL > 5.5 V Application
      15. 8.2.15 LM2735X-Q1 SOT-23 LED Design Example 17 Two-Input Voltage Rail Application
      16. 8.2.16 SEPIC Converter
        1. 8.2.16.1 Detailed Design Procedure
          1. 8.2.16.1.1 SEPIC Design Guide
          2. 8.2.16.1.2 Small Ripple Approximation
          3. 8.2.16.1.3 Steady State Analysis With Loss Elements
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 WSON Package
    2. 10.2 Layout Examples
    3. 10.3 Thermal Considerations
      1. 10.3.1 Definitions
      2. 10.3.2 PCB Design With Thermal Performance in Mind
      3. 10.3.3 LM2735-Q1 Thermal Models
      4. 10.3.4 Calculating Efficiency, and Junction Temperature
        1. 10.3.4.1 Example Efficiency Calculation
      5. 10.3.5 Calculating RθJA and RΨJC
        1. 10.3.5.1 Procedure
        2. 10.3.5.2 Example From Previous Calculations
  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 ドキュメントの更新通知を受け取る方法
    5. 11.5 コミュニティ・リソース
    6. 11.6 商標
    7. 11.7 静電気放電に関する注意事項
    8. 11.8 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

8.2.1.2.4 Output Capacitor

The LM2735-Q1 operates at frequencies allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple. The output capacitor is selected based upon the desired output ripple and transient response. The initial current of a load transient is provided mainly by the output capacitor. The output impedance therefore determines the maximum voltage perturbation. The output ripple of the converter is a function of the reactance of the capacitor and its equivalent series resistance (ESR):

Equation 15. LM2735-Q1 20215828.gif

When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple is approximately sinusoidal and 90° phase shifted from the switching action.

Given the availability and quality of MLCCs and the expected output voltage of designs using the LM2735-Q1, there is really no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass high-frequency noise. A certain amount of switching edge noise couples through parasitic capacitances in the inductor to the output. A ceramic capacitor bypasses this noise while a tantalum does not. Since the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications require a minimum at 4.7 µF of output capacitance. Like the input capacitor, recommended multilayer ceramic capacitors are X7R or X5R. Again, verify actual capacitance at the desired operating voltage and temperature.