SNVS470I January   2007  – November 2025 LM25576

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 High Voltage Start-Up Regulator
    4. 6.4 Device Functional Modes
      1. 6.4.1 Shutdown and Stand-by Mode
      2. 6.4.2 Oscillator and Sync Capability
      3. 6.4.3 Error Amplifier and PWM Comparator
      4. 6.4.4 RAMP Generator
      5. 6.4.5 Maximum Duty Cycle and Input Drop-Out Voltage
      6. 6.4.6 Current Limit
      7. 6.4.7 Soft Start
      8. 6.4.8 Boost Pin
      9. 6.4.9 Thermal Protection
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Bias Power Dissipation Reduction
    2. 7.2 Typical Application
      1. 7.2.1 Typical Schematic for High Frequency (1 MHz) Application
      2. 7.2.2 Typical Schematic for Buck and Boost (Inverting) Application
      3. 7.2.3 Design Requirements
        1. 7.2.3.1  R3 (RT)
        2. 7.2.3.2  L1
        3. 7.2.3.3  C3 (CRAMP)
        4. 7.2.3.4  C9, C10
        5. 7.2.3.5  D1
        6. 7.2.3.6  C1, C2
        7. 7.2.3.7  C8
        8. 7.2.3.8  C7
        9. 7.2.3.9  C4
        10. 7.2.3.10 R5, R6
        11. 7.2.3.11 R1, R2, C12
        12. 7.2.3.12 R7, C11
        13. 7.2.3.13 R4, C5, C6
      4. 7.2.4 Detailed Design Procedure
        1. 7.2.4.1 Custom Design With WEBENCH® Tools
      5. 7.2.5 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 PCB Layout
      2. 7.4.2 Layout Example
      3. 7.4.3 Power Dissipation
      4. 7.4.4 Thermal Considerations
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Developmental Support
        1. 8.1.1.1 Custom Design With WEBENCH® Tools
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.2.3.11 R1, R2, C12

A voltage divider can be connected to the SD pin to set a minimum operating voltage Vin(min) for the regulator. If this feature is required, the easiest approach to select the divider resistor values is to select a value for R1 (between 10 kΩ and 100 kΩ recommended) then calculate R2 from:

Equation 12. LM25576

Capacitor C12 provides filtering for the divider. The voltage at the SD pin must never exceed 8 V, when using an external set-point divider, clamping the SD pin at high input voltage conditions can be necessary. The reference design uses the full range of the LM25576 (6 V to 42 V); therefore, these components can be omitted. With the SD pin open circuit, the LM25576 responds after the Vcc UVLO threshold is satisfied.