SNAS744B
July 2017 – March 2018
LMS3655
PRODUCTION DATA.
1
Features
2
Applications
3
Description
Device Images
Typical Application Circuit
LMS3655 Efficiency: VOUT = 5 V
4
Revision History
5
Device Comparison Table
6
Pin Configuration and Functions
Pin Functions
7
Specifications
7.1
Absolute Maximum Ratings
7.2
ESD Ratings
7.3
Recommended Operating Conditions
7.4
Thermal Information
7.5
Thermal Information (for Device Mounted on PCB)
7.6
Electrical Characteristics
7.7
System Characteristics
7.8
Timing Requirements
7.9
Typical Characteristics
8
Detailed Description
8.1
Overview
8.2
Functional Block Diagram
8.2.1
Control Scheme
8.3
Feature Description
8.3.1
RESET Flag Output
8.3.2
Enable and Start-Up
8.3.3
Soft-Start Function
8.3.4
Current Limit
8.3.5
Hiccup Mode
8.3.6
Synchronizing Input
8.3.7
Undervoltage Lockout (UVLO) and Thermal Shutdown (TSD)
8.3.8
Input Supply Current
8.4
Device Functional Modes
8.4.1
AUTO Mode
8.4.2
FPWM Mode
8.4.3
Dropout
8.4.4
Spread-Spectrum Operation
9
Application and Implementation
9.1
Application Information
9.2
Typical Applications
9.2.1
General Application
9.2.1.1
Design Requirements
9.2.1.2
Detailed Design Procedure
9.2.1.2.1
External Components Selection
9.2.1.2.1.1
Input Capacitors
9.2.1.2.1.2
Output Inductors and Capacitors
9.2.1.2.1.2.1
Inductor Selection
9.2.1.2.1.2.2
Output Capacitor Selection
9.2.1.2.2
FB for Adjustable Output
9.2.1.2.3
VCC
9.2.1.2.4
BIAS
9.2.1.2.5
CBOOT
9.2.1.2.6
Maximum Ambient Temperature
9.2.1.3
Application Curves
9.2.2
Adjustable 5-V Output
9.2.2.1
Design Requirements
9.2.2.2
Detailed Design Procedure
9.2.2.3
Application Curves
9.2.3
Adjustable 3.3-V Output
9.2.3.1
Design Requirements
9.2.3.2
Detailed Design Procedure
9.2.3.3
Application Curves
9.2.4
6-V Adjustable Output
9.2.4.1
Design Requirements
9.2.4.2
Detailed Design Procedure
9.2.4.3
Application Curves
9.3
Do's and Don't's
10
Power Supply Recommendations
11
Layout
11.1
Layout Guidelines
11.2
Layout Example
12
Device and Documentation Support
12.1
Device Support
12.1.1
Third-Party Products Disclaimer
12.2
Documentation Support
12.2.1
Related Documentation
12.3
Receiving Notification of Documentation Updates
12.4
Community Resources
12.5
Trademarks
12.6
Electrostatic Discharge Caution
12.7
Glossary
13
Mechanical, Packaging, and Orderable Information
Package Options
Mechanical Data (Package|Pins)
RNL|22
MPQF443E
Thermal pad, mechanical data (Package|Pins)
RNL|22
QFND673
Orderable Information
snas744b_oa
1
Features
96% Peak Efficiency While Converting 12 V to 5 V
Low EMI and Switch Noise
Minimized Switch Node Ringing
Pseudo-Random Spread Spectrum
400-kHz (±10%) Fixed Switching Frequency
–40°C to +150°C Junction Temperature Range
External Frequency Synchronization
RESET
Output With Internal Filter and 3-ms Release Timer
Automatic Light Load Mode for Improved Efficiency
Pin-Selectable Forced PWM Mode
Built-In Compensation, Soft Start, Current Limit, Thermal Shutdown, and UVLO
0.35-V Dropout With 3.5-A Load at 25°C (Typical)
32-µA I
Q_VIN
: Quiescent Current at 3.3 V
OUT
and No Load (Typical)
5.5-A Continuous Load Current
Adjustable Output Voltage (1 V to 20 V)
±1.5% Reference Voltage Tolerance
4-mm × 5-mm, 0.5-mm Pitch SON Package