SNOSB24C October   2008  – November 2025 LM5576-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 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 Shutdown / Standby
      2. 6.3.2 Soft Start
      3. 6.3.3 Thermal Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 High Voltage Start-Up Regulator
      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 / Input Dropout Voltage
      6. 6.4.6 Boost Pin
      7. 6.4.7 Current Limit
  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 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1  Custom Design With WEBENCH® Tools
        2. 7.2.2.2  External Components
        3. 7.2.2.3  R3 (RT)
        4. 7.2.2.4  L1
        5. 7.2.2.5  C3 (CRAMP)
        6. 7.2.2.6  C9, C10
        7. 7.2.2.7  D1
        8. 7.2.2.8  C1, C2
        9. 7.2.2.9  C8
        10. 7.2.2.10 C7
        11. 7.2.2.11 C4
        12. 7.2.2.12 R5, R6
        13. 7.2.2.13 R1, R2, C12
        14. 7.2.2.14 R7, C11
        15. 7.2.2.15 R4, C5, C6
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      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 Development 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

6.1 Overview

The LM5576-Q1 switching regulator features all of the functions necessary to implement an efficient high voltage buck regulator using a minimum of external components. This easy to use regulator integrates a 75V N-Channel buck switch with an output current capability of 3 Amps. The regulator control method is based on current mode control uses an emulated current ramp. Peak current mode control provides inherent line voltage feed-forward, cycle-by-cycle current limiting, and ease-of-loop compensation. The use of an emulated control ramp reduces noise sensitivity of the pulse width modulation circuit, which allows reliable processing of very small duty cycles necessary in high input voltage applications. The operating frequency is user programmable from 50kHz to 500kHz. An oscillator synchronization pin allows multiple LM5576-Q1 regulators to self-synchronize or be synchronized to an external clock. The output voltage can be set as low as 1.225V. Fault protection features include current limiting, thermal shutdown, and remote shutdown capability. The device is available in the 20-pin HTSSOP package that features an exposed pad to help thermal dissipation.

The functional block diagram and typical application of the LM5576-Q1 are shown in the Section 6.2 section. The LM5576-Q1 can be applied in numerous applications to efficiently step-down a high, unregulated input voltage. The device is designed for telecom, industrial power bus voltage ranges.