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LM3481 High-Efficiency Controller for Boost, SEPIC and Flyback DC/DC Converters
SNVS346H
November 2007 – October 2024
LM3481
PRODUCTION DATA
CONTENTS
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LM3481 High-Efficiency Controller for Boost, SEPIC and Flyback DC/DC Converters
1
1
Features
2
Applications
3
Description
4
Pin Configuration and Functions
Pin Functions
5
Specifications
5.1
Absolute Maximum Ratings
5.2
ESD Ratings: LM3481
5.3
Recommended Operating Ratings
5.4
Thermal Information
5.5
Electrical Characteristics
5.6
Typical Characteristics
6
Detailed Description
6.1
Overview
6.2
Functional Block Diagram
6.3
Feature Description
6.3.1
Overvoltage Protection
6.3.2
Bias Voltage
6.3.3
Slope Compensation Ramp
6.3.4
Frequency Adjust, Synchronization, and Shutdown
6.3.5
Undervoltage Lockout (UVLO) Pin
6.3.6
Short-Circuit Protection
6.4
Device Functional Modes
7
Application and Implementation
7.1
Application Information
7.2
Typical Applications
7.2.1
Boost Converter
7.2.1.1
Design Requirements
7.2.1.2
Detailed Design Procedure
7.2.1.2.1
Custom Design with WEBENCH Tools
7.2.1.2.2
Power Inductor Selection
7.2.1.2.3
Programming the Output Voltage and Output Current
7.2.1.2.4
Current Limit With Additional Slope Compensation
7.2.1.2.5
Power Diode Selection
7.2.1.2.6
Power MOSFET Selection
7.2.1.2.7
Input Capacitor Selection
7.2.1.2.8
Output Capacitor Selection
7.2.1.2.9
Driver Supply Capacitor Selection
7.2.1.2.10
Compensation
7.2.1.3
Application Curve
7.2.2
Typical SEPIC Converter
7.2.2.1
Design Requirements
7.2.2.2
Detailed Design Procedure
7.2.2.2.1
Power MOSFET Selection
7.2.2.2.2
Power Diode Selection
7.2.2.2.3
Selection of Inductors L1 and L2
7.2.2.2.4
Sense Resistor Selection
7.2.2.2.5
SEPIC Capacitor Selection
7.2.2.2.6
Input Capacitor Selection
7.2.2.2.7
Output Capacitor Selection
7.2.2.3
Application Curve
7.3
Power Supply Recommendations
7.4
Layout
7.4.1
Layout Guidelines
7.4.2
Layout Example
8
Device and Documentation Support
8.1
Documentation Support
8.1.1
Custom Design with WEBENCH Tools
8.1.2
Related Documentation
8.2
Receiving Notification of Documentation Updates
8.3
Support Resources
8.4
Trademarks
9
Revision History
10
Mechanical, Packaging, and Orderable Information
IMPORTANT NOTICE
Package Options
Mechanical Data (Package|Pins)
DGS|10
MPDS035C
Thermal pad, mechanical data (Package|Pins)
Orderable Information
snvs346h_oa
snvs346h_pm
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Data Sheet
LM3481
High-Efficiency Controller for Boost, SEPIC and Flyback DC/DC Converters
1
Features
10-Lead VSSOP package
Internal push-pull driver with 1A peak current capability
Current limit and thermal shutdown
Frequency compensation optimized with a capacitor and a resistor
Internal soft start
Current mode operation
Adjustable undervoltage lockout with hysteresis
Pulse skipping at light loads
Key specifications
Wide supply voltage range of 2.97V to 48V
100kHz to 1MHz Adjustable and synchronizable clock frequency
±1.5% (over temperature) internal reference
10µA shutdown current (over temperature)
Create a custom design using the LM3481 with the
WEBENCH Power Designer
2
Applications
Boost for audio amplifiers in portable speakers
Wide input boost, SEPIC, flyback power module
Isolated Supply (Flyback)
Battery-powered boost, SEPIC, flyback