JAJSVT7 December   2024 LMG5126

ADVANCE INFORMATION  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Device Configuration
      2. 6.3.2 Switching Frequency and Synchronization (SYNCIN)
      3. 6.3.3 Dual Random Spread Spectrum (DRSS)
      4. 6.3.4 Operation Modes (BYPASS, DEM, FPWM)
    4. 6.4 Device Functional Modes
      1. 6.4.1 Shutdown State
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Feedback Compensation
    2. 7.2 Typical Application
      1. 7.2.1 Application
      2. 7.2.2 Design Requirements
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Determining the Duty Cycle
        2. 7.2.3.2 Timing Resistor RT
        3. 7.2.3.3 Vout Programming
        4. 7.2.3.4 Inductor Selection Lm
        5. 7.2.3.5 Output Capacitor Cout
      4. 7.2.4 Application Curves
        1. 7.2.4.1 Efficiency
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 ドキュメントの更新通知を受け取る方法
    2. 8.2 サポート・リソース
    3. 8.3 Trademarks
    4. 8.4 静電気放電に関する注意事項
    5. 8.5 用語集
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Package Option Addendum
    2. 10.2 Tape and Reel Information
    3. 10.3 Mechanical Data

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）
  • VBT|22
サーマルパッド・メカニカル・データ

7.2.3.3 Vout Programming

For fixed output voltage, VOUT can be programmed by connecting a resistor to ATRK/DTRK and turn on precise internal 20μA current source.

Equation 9. RATRK=Vout_max6V×10kΩ=100kΩ

For class-H audio application, Vout can be adjusted to optimize the efficiency. Analog tracking or digital tracking can be applied with ATRK/DTRK.

For analog tracking, apply a voltage to ATRK/DTRK to program Vout. The voltage can be found as:

Equation 10. VATRK_max=Vout_max30=2V
Equation 11. VATRK_min=Vout_min30=0.8V

The output voltage can also be programmed by digital PWM signal (DTRK). The duty cycle DTRK can be found as:

Equation 12. DTRK=Vout_max0.75V×100%=80%
Equation 13. DTRK_min=Vout_min0.75V×100%=32%

Make sure the DTRK frequency is between 100kHz and 2200kHz.

A two stage RC filter with offset can be utilized to convert a digital PWM signal to analog voltage as shown in Figure 7-3.

The two stage RC filter is used to filter the PWM signal into a smooth analog voltage. The two stage RC filter is selected considering voltage ripple and rise time on ATRK/DTRK.

Pullup resistor (RPU) and pulldown resistor (RPD) are utilized to add an offset voltage to ATRK/DTRK so that 100% PWM duty cycle sets the output voltage to Vout_max and 0% PWM duty cycle sets the output voltage to Vout_min.

LMG5126 Two Stage RC Filter to ATRK/DTRKFigure 7-3 Two Stage RC Filter to ATRK/DTRK