JAJSMU5B may   2023  – july 2023 TPSM843B22

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  VIN Pins and VIN UVLO
      2. 7.3.2  Internal Bypassing (BP5)
      3. 7.3.3  Enable and Adjustable UVLO
        1. 7.3.3.1 Internal Sequence of Events During Start-up
      4. 7.3.4  Switching Frequency Selection
      5. 7.3.5  Switching Frequency Synchronization to an External Clock
        1. 7.3.5.1 Internal PWM Oscillator Frequency
        2. 7.3.5.2 Loss of Synchronization
        3. 7.3.5.3 Interfacing the SYNC/FSEL Pin
      6. 7.3.6  Remote Sense Amplifier and Adjusting the Output Voltage
      7. 7.3.7  Loop Compensation Guidelines
        1. 7.3.7.1 Output Filter Inductor Tradeoffs
        2. 7.3.7.2 Ramp Capacitor Selection
        3. 7.3.7.3 Output Capacitor Selection
        4. 7.3.7.4 Design Method for Good Transient Response
      8. 7.3.8  Soft Start and Prebiased Output Start-up
      9. 7.3.9  MSEL Pin
      10. 7.3.10 Power Good (PG)
      11. 7.3.11 Output Overload Protection
        1. 7.3.11.1 Positive Inductor Current Protection
        2. 7.3.11.2 Negative Inductor Current Protection
      12. 7.3.12 Output Overvoltage and Undervoltage Protection
      13. 7.3.13 Overtemperature Protection
      14. 7.3.14 Output Voltage Discharge
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forced Continuous-Conduction Mode
      2. 7.4.2 Discontinuous Conduction Mode During Soft Start
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 1.0-V Output, 1-MHz Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Switching Frequency
          2. 8.2.1.2.2  Output Inductor Selection
          3. 8.2.1.2.3  Output Capacitor
          4. 8.2.1.2.4  Input Capacitor
          5. 8.2.1.2.5  Adjustable Undervoltage Lockout
          6. 8.2.1.2.6  Output Voltage Resistors Selection
          7. 8.2.1.2.7  Bootstrap Capacitor Selection
          8. 8.2.1.2.8  BP5 Capacitor Selection
          9. 8.2.1.2.9  PG Pullup Resistor
          10. 8.2.1.2.10 Current Limit Selection
          11. 8.2.1.2.11 Soft-Start Time Selection
          12. 8.2.1.2.12 Ramp Selection and Control Loop Stability
          13. 8.2.1.2.13 MSEL Pin
        3. 8.2.1.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
      3. 8.4.3 Thermal Performance
  10. 9 Device and Documentation Support
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 サポート・リソース
    3. 9.3 Trademarks
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 用語集
  11. 10Mechanical, Packaging, and Orderable Information

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

7.3.8 Soft Start and Prebiased Output Start-up

During start-up, the device softly increases the reference voltage from zero to its final value, thereby reducing converter inrush current. There are four options for the soft-start time, which is the time it takes for the reference to ramp to 0.5 V:

  • 1 ms
  • 2 ms
  • 4 ms
  • 8 ms

The soft-start time is selected with a resistor to AGND on the MSEL pin. See Section 7.3.9.

If a prebiased output condition exists prior to start-up, the device prevents current from being discharged from the output. During monotonic prebiased start-up, the low-side MOSFET is not allowed to sink current until the SS pin voltage is higher than the FB pin voltage and the high-side MOSFET begins to switch. The one exception is if the BOOT-SW voltage is below its UVLO threshold. While in BOOT-SW UVLO, the low-side MOSFET is allowed to turn on to charge the BOOT capacitor. The low-side MOSFET reverse current protection provides another layer of protection for the device after the high-side MOSFET begins to switch.