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

6.1 Overview

The LM25576-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 42V N-Channel buck switch with an output current capability of 3 Amps. The regulator control method is based on current mode control utilizing 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, allowing reliable processing of very small duty cycles necessary in high input voltage applications. The operating frequency is user programmable from 50kHz to 1MHz. An oscillator synchronization pin allows multiple LM25576-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 HTSSOP-20 package featuring an exposed pad to aid thermal dissipation.

The functional block diagram and typical application of the LM25576-Q1 are shown in Section 6.2. The LM25576-Q1 can be applied in numerous applications to efficiently step-down a high, unregulated input voltage. The device is well suited for telecom, industrial power bus voltage ranges.