ZHCSKV1A February   2020  – July 2020 LM76005

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  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  Bootstrap Voltage and VBOOT UVLO (BOOT Pin)
      10. 7.3.10 Power Good and Overvoltage Protection (PGOOD)
      11. 7.3.11 Overcurrent and Short-Circuit Protection
      12. 7.3.12 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
  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  Feedforward 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
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Support Resources
  12. 12Mechanical, Packaging, and Orderable Information

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8.2 Typical Applications

The LM76005 only requires a few external components to convert from a wide range of supply voltages to output voltage, as shown in Figure 8-1:

GUID-D9ADFDED-330D-4D3A-8486-329D06239B98-low.gifFigure 8-1 LM76005 Basic Schematic

The LM76005 also integrates a full list of features to aid system design requirements, such as the following:

  • VCC UVLO
  • Programmable soft start
  • Start-up tracking
  • Programmable switching frequency
  • Clock synchronization
  • Power-good indication

Each system can select the features needed in a specific application. A comprehensive schematic with all features utilized is shown in Figure 8-2:

GUID-7E6C5153-B124-4C5D-96AD-3F1E14681DBA-low.gifFigure 8-2 LM76005 Comprehensive Schematic

The external components must fulfill the requirements of the application, but also the stability criteria of the device control loop. The LM76005 is optimized to work within a range of external components. Inductance and capacitance of the LC output filter each create poles that have to be considered in the control of the converter. For VOUT = 1 V, 3.3 V, 5V, the recommended output capacitors have been generated assuming typical derating for 16-V, X7R, automotive grade capacitors. For VOUT = 12 V, the recommended output capacitors have been generated assuming typical derating for 25-V, X7R, automotive grade capacitors, and for VOUT = 24 V, the recommended output capacitors have been generated assuming typical derating for 50-V, X7R, automotive grade capacitors. If lower voltage, nonautomotive grade, or lower temperature rated capacitors are used, more capacitors than listed are likely to be needed.Table 8-1 can be used to simplify the output filter component selection.

Table 8-1 Typical Component Selection
fSW (kHz)VOUT (V)L (µH)COUT (µF)RFBT (kΩ)RFBB (kΩ)
20012.5720100OPEN
40011.2600100OPEN
50011470100OPEN
2003.31030010043.5
4003.34.722010043.5
5003.34.720010043.5
20051525010025
40056.818010025
50055.215010025
20012222001009.09
40012101501009.09
500127.21201009.09
20024441501004.37
40024221001004.37
5002415881004.37