JAJSE25A October   2017  – October 2019 LM76002 , LM76003

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     概略回路図
    2.     効率と出力電流との関係 (VOUT＝5V、fSW＝400kHz、自動モード)
  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 Timing Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 System Characteristics
    9. 6.9 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  Fixed-Frequency, Peak-Current-Mode Control
      2. 7.3.2  Light Load Operation Modes — PFM and FPWM
      3. 7.3.3  Adjustable Output Voltage
      4. 7.3.4  Enable (EN Pin) and UVLO
      5. 7.3.5  Internal LDO, VCC UVLO, and Bias Input
      6. 7.3.6  Soft Start and Voltage Tracking (SS/TRK)
      7. 7.3.7  Adjustable Switching Frequency (RT) and Frequency Synchronization
      8. 7.3.8  Minimum On-Time, Minimum Off-Time, and Frequency Foldback at Dropout Conditions
      9. 7.3.9  Internal Compensation and CFF
      10. 7.3.10 Bootstrap Voltage and VBOOT UVLO (BOOT Pin)
      11. 7.3.11 Power Good and Overvoltage Protection (PGOOD)
      12. 7.3.12 Overcurrent and Short-Circuit Protection
      13. 7.3.13 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
      4. 7.4.4 CCM Mode
      5. 7.4.5 DCM Mode
      6. 7.4.6 Light Load Mode
      7. 7.4.7 Foldback Mode
      8. 7.4.8 Forced Pulse-Width-Modulation Mode
      9. 7.4.9 Self-Bias Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Output Voltage Setpoint
        3. 8.2.2.3  Switching Frequency
        4. 8.2.2.4  Input Capacitors
        5. 8.2.2.5  Inductor Selection
        6. 8.2.2.6  Output Capacitor Selection
        7. 8.2.2.7  Feed-Forward Capacitor
        8. 8.2.2.8  Bootstrap Capacitors
        9. 8.2.2.9  VCC Capacitors
        10. 8.2.2.10 BIAS Capacitors
        11. 8.2.2.11 Soft-Start Capacitors
        12. 8.2.2.12 Undervoltage Lockout Setpoint
        13. 8.2.2.13 PGOOD
        14. 8.2.2.14 Synchronization
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Layout Highlights
      2. 10.1.2 Compact Layout for EMI Reduction
      3. 10.1.3 Ground Plane and Thermal Considerations
      4. 10.1.4 Feedback Resistors
    2. 10.2 Layout Example
    3. 10.3 Thermal Design
  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 開発サポート
        1. 11.1.1.1 WEBENCH®ツールによるカスタム設計
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 サポート・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

7.4.3 Active Mode

The LM76002/LM76003 is in active mode when the EN pin and UVLO high threshold levels are satisfied. The simplest way to enable the operation of the LM76002/LM76003 is to connect the EN pin to VIN, which allows self start-up of the LM76002/LM76003 when the input voltage is in the operation range: 3.5 V to 60 V. See Enable (EN Pin) and UVLO for details on setting these operating levels.

In active mode, depending on the load current, the LM76002/LM76003 will be in one of five sub modes:

  1. CCM with fixed switching frequency with load between half of IMINPK to full load.
  2. DCM when the load current is lower than half of the inductor current ripple.
  3. Light load mode where the device uses pulse frequency modulation (PFM) and lowers the switching frequency at load under half of IMINPK to improve efficiency.
  4. Foldback mode when switching frequency is reduced to maintain output regulation with supply voltages that cause the minimum tON or tOFF to be exceeded.
  5. Forced-pulse-width modulation (FPWM) is similar to CCM with fixed switching frequency, but extends the fixed frequency range of operation from full to no load.