JAJSON4 May   2022 TPS92643-Q1

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 Revision History
  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 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  Internal Regulator
      2. 7.3.2  Buck Converter Switching Operation
      3. 7.3.3  Bootstrap Supply
      4. 7.3.4  Switching Frequency and Adaptive On-Time Control
      5. 7.3.5  Minimum On-Time, Off-Time, and Inductor Ripple
      6. 7.3.6  LED Current Regulation and Error Amplifier
      7. 7.3.7  Start-Up Sequence
      8. 7.3.8  Analog Dimming and Forced Continuous Conduction Mode
      9. 7.3.9  External PWM Dimming and Input Undervoltage Lockout (UVLO)
      10. 7.3.10 Analog Pulse Width Modulator Circuit
      11. 7.3.11 Output Short and Open-Circuit Faults
      12. 7.3.12 Overcurrent Protection
      13. 7.3.13 Thermal Shutdown
      14. 7.3.14 Fault Indicator and Diagnostics Summary
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Duty Cycle Considerations
      2. 8.1.2  Switching Frequency Selection
      3. 8.1.3  LED Current Programming
      4. 8.1.4  Inductor Selection
      5. 8.1.5  Output Capacitor Selection
      6. 8.1.6  Input Capacitor Selection
      7. 8.1.7  Bootstrap Capacitor Selection
      8. 8.1.8  Bootstrap Resistor Selection
      9. 8.1.9  Compensation Capacitor Selection
      10. 8.1.10 Input Dropout and Undervoltage Protection
      11. 8.1.11 APWM Input and Thermal Protection
      12. 8.1.12 Protection Diodes
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Calculating Duty Cycle
        2. 8.2.2.2  Calculating Minimum On-Time and Off-Time
        3. 8.2.2.3  Minimum Switching Frequency
        4. 8.2.2.4  LED Current Set Point
        5. 8.2.2.5  Inductor Selection
        6. 8.2.2.6  Output Capacitor Selection
        7. 8.2.2.7  Bootstrap Capacitor Selection
        8. 8.2.2.8  Bootstrap Resistor Selection
        9. 8.2.2.9  Compensation Capacitor Selection
        10. 8.2.2.10 VIN Dropout Protection and PWM Dimming
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact Layout for EMI Reduction
        1. 10.1.1.1 Ground Plane
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 サポート・リソース
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, 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

8.1.10 Input Dropout and Undervoltage Protection

Figure 8-1 shows that the undervoltage protection threshold is programmed using a resistor divider, RUV1 and RUV2, from the input voltage, VIN to PGND. Use Equation 23 and Equation 24 to calculate the resistor values.

Equation 23. RUV2=2×VIN(UVLO,RISE)IUDIM(DO)-VIN(DO,FALL)IUDIM(DO)-10×103
Equation 24. RUV1=VUDIM(EN,RISE)VIN(UVLO,RISE)-VUDIM(EN,RISE)×RUV2

A capacitor of 1 nF from UDIM pin to GND is placed close to device to improve noise immunity.