SNVSCD3
September 2024
LM70840
,
LM70860
,
LM70880
PRODUCTION DATA
1
1
Features
2
Applications
3
Description
4
Pin Configuration and Functions
5
Specifications
5.1
Absolute Maximum Ratings
5.2
ESD Ratings
5.3
Recommended Operating Conditions
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
Input Voltage Range (VIN)
6.3.2
High-Voltage Bias Supply Regulator (VCC, BIAS, VDDA)
6.3.3
Enable (EN)
6.3.4
Power-Good Monitor (PG)
6.3.5
Switching Frequency (RT)
6.3.6
Dual Random Spread Spectrum (DRSS)
6.3.7
Soft Start
6.3.8
Output Voltage Setpoint (FB)
6.3.9
Minimum Controllable On-Time
6.3.10
Error Amplifier and PWM Comparator (FB, EXTCOMP)
6.3.11
Slope Compensation
6.3.12
Shunt Current Sensing
6.3.13
Hiccup Mode Current Limiting
6.3.14
Device Configuration (CONFIG)
6.3.15
Single-Output Dual-Phase Operation
6.3.16
Pulse Frequency Modulation (PFM) / Synchronization
6.3.17
Thermal Shutdown (TSD)
6.4
Device Functional Modes
6.4.1
Shutdown Mode
6.4.2
Standby Mode
6.4.3
Active Mode
6.4.4
Sleep Mode
7
Application and Implementation
7.1
Application Information
7.1.1
Power Train Components
7.1.1.1
Buck Inductor
7.1.1.2
Output Capacitors
7.1.1.3
Input Capacitors
7.1.1.4
EMI Filter
7.1.2
Error Amplifier and Compensation
7.1.3
Maximum Ambient Temperature
7.1.3.1
Derating Curves
7.2
Typical Applications
7.2.1
Design 1 – High Efficiency, Wide Input, 400kHz Synchronous Buck Regulator
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
Custom Design With Excel Quickstart Tool
7.2.1.2.3
Buck Inductor
7.2.1.2.4
Current-Sense Resistance
7.2.1.2.5
Output Capacitors
7.2.1.2.6
Input Capacitors
7.2.1.2.7
Frequency Set Resistor
7.2.1.2.8
Feedback Resistors
7.2.1.2.9
Compensation Components
7.2.1.3
Application Curves
7.2.2
Design 2 – High Efficiency 48V to 12V 400kHz Synchronous Buck Regulator
7.2.2.1
Design Requirements
7.2.2.2
Detailed Design Procedure
7.2.2.3
Application Curves
7.3
Power Supply Recommendations
7.4
Layout
7.4.1
Layout Guidelines
7.4.1.1
Thermal Design and Layout
7.4.2
Layout Example
8
Device and Documentation Support
8.1
Device Support
8.1.1
Development Support
8.1.1.1
Custom Design With WEBENCH® Tools
8.2
Documentation Support
8.2.1
Related Documentation
8.2.1.1
PCB Layout Resources
8.2.1.2
Thermal Design Resources
8.3
Receiving Notification of Documentation Updates
8.4
Support Resources
8.5
Trademarks
8.6
Electrostatic Discharge Caution
8.7
Glossary
9
Revision History
10
Mechanical, Packaging, and Orderable Information
10.1
Tape and Reel Information
6.2
Functional Block Diagram