SNVSB42A December   2017  – December 2025 LM25576-Q1

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 Resistance Characteristics
    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 Design Requirements
      2. 7.1.2 Detailed Design Procedure
        1. 7.1.2.1  R3 (RT)
        2. 7.1.2.2  Inductor (L1)
        3. 7.1.2.3  C3 (CRAMP)
        4. 7.1.2.4  C9, C10
        5. 7.1.2.5  D1
        6. 7.1.2.6  C1, C2
        7. 7.1.2.7  C8
        8. 7.1.2.8  C7
        9. 7.1.2.9  C4
        10. 7.1.2.10 R5, R6
        11. 7.1.2.11 R1, R2, C12
        12. 7.1.2.12 R7, C11
        13. 7.1.2.13 R4, C5, C6
      3. 7.1.3 Bias Power Dissipation Reduction
    2. 7.2 Typical Application
      1. 7.2.1 Typical Schematic for High Frequency (1MHz) Application
      2. 7.2.2 Typical Schematic for Buck and Boost (Inverting) Application
      3. 7.2.3 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 and Thermal Considerations
      2. 7.4.2 Layout Example
  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 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 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

6.4.1 Shutdown and Stand-by Mode

The LM25576-Q1 contains a dual level Shutdown (SD) circuit. When the SD pin voltage is below 0.7V, the regulator is in a low current shutdown mode. When the SD pin voltage is greater than 0.7V but less than 1.225V, the regulator is in standby mode. In standby mode the VCC regulator is active but the output switch is disabled. When the SD pin voltage exceeds 1.225V, the output switch is enabled and normal operation begins. An internal 5µA pull-up current source configures the regulator to be fully operational if the SD pin is left open.

Use an external set-point voltage divider from VIN to GND to set the operational input range of the regulator. Design the divider so that the voltage at the SD pin is be greater than 1.225V when Vin is in the desired operating range. Include the internal 5µA pull-up current source in calculations of the external set-point divider. Both the shutdown and standby thresholds include hysteresis of 0.1V. The SD pin internally clamps with a 1kΩ resistor and an 8V zener clamp. Ensure that the voltage at the SD pin never exceeds 14V. If the voltage at the SD pin exceeds 8V, the bias current increases at a rate of 1mA/V.

Use the SD pin to implement various remote enable and disable functions. Pulling the SD pin below the 0.7V threshold totally disables the controller. If the SD pin voltage is above 1.225V, the regulator is operational.