ZHCSM35F January   2007  – May 2021 LM5002

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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 High Voltage VCC Regulator
      2. 7.3.2 Oscillator
      3. 7.3.3 External Synchronization
      4. 7.3.4 Enable and Standby
      5. 7.3.5 Error Amplifier and PWM Comparator
      6. 7.3.6 Current Amplifier and Slope Compensation
      7. 7.3.7 Power MOSFET
    4. 7.4 Device Functional Modes
      1. 7.4.1 Thermal Protection
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 VIN
      2. 8.1.2 SW PIN
      3. 8.1.3 EN or UVLO Voltage Divider Selection
      4. 8.1.4 Soft Start
    2. 8.2 Typical Applications
      1. 8.2.1 Non-Isolated Flyback Regulator
        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 Flyback Transformer
          3. 8.2.1.2.3 Peak MOSFET Current
          4. 8.2.1.2.4 Output Capacitance
          5. 8.2.1.2.5 Output Diode Rating
          6. 8.2.1.2.6 Power Stage Analysis
          7. 8.2.1.2.7 Loop Compensation
      2. 8.2.2 Isolated Flyback Regulator
        1. 8.2.2.1 Design Requirements
      3. 8.2.3 Boost Regulator
        1. 8.2.3.1 Design Requirements
      4. 8.2.4 24-V SEPIC Regulator
        1. 8.2.4.1 Design Requirements
      5. 8.2.5 12-V Automotive SEPIC Regulator
        1. 8.2.5.1 Design Requirements
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 接收文档更新通知
    2. 11.2 支持资源
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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8.2.5.1 Design Requirements

The 12-V automotive SEPIC converter shown in Figure 8-9 uses the internal bandgap voltage reference for the regulation setpoint. The output is 12 V at 25 mA while the input voltage can vary from 3.1 V to 60 V. The output current rating can be increased if the minimum VIN voltage requirement is increased. The switching frequency is set to 750 kHz. The internal VCC regulator provides 6.9-V bias power for the LM5002. The output voltage can be used as an auxiliary voltage if the nominal VIN voltage is greater than 12 V by adding a diode from the output into the VCC pin. In this configuration, the minimum input voltage must be greater than 12 V to prevent the internal VCC to VIN diode from conducting. If the applied VCC voltage exceeds the minimum VIN voltage, then an external blocking diode is required between the VIN pin and the power source to block current flow from VCC to the input supply.