LTC3311S

5V, 12.5A Synchronous Step-Down Silent Switcher 2 in 3mm x 3mm LQFN

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Recommended for New Designs

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New Content (2)

Books & eBooks

Understanding Silent Switcher Technology: High Efficiency, Low EMI eBook

Solutions Bulletins & Brochures

Silent Switcher Technology

Overview

Features and Benefits
Product Details

Features and Benefits

Pin Compatible with LTC3310/LTC3310S and LTC3311
Silent Switcher^®2 Architecture:
Ultralow EMI Emissions
High Efficiency—4.5mΩ NMOS & 16mΩ PMOS
Wide Bandwidth, Fast Transient Response
Safely Tolerates Inductor Saturation in Overload
V_IN Range: 2.25V to 5.5V
V_OUT Range: 0.5V to V_IN
V_OUT Accuracy: ±1% with Remote Sense
Peak Current Mode Control
Minimum On-Time: 35ns

Programmable Frequency to 5MHz
Shutdown Current: 1μA
Precision 400mV Enable Threshold, 1μA in Shutdown
Output Soft-Start with Voltage Tracking
Power Good Output
Die Temperature Monitor
Configurable for Paralleling Power Stages in Forced Continuous Mode
Thermally-Enhanced 3mm × 3mm LQFN Package
AEC-Q100 Qualified for Automotive Applications

Product Details

The LTC3311S is a very small, low noise, monolithic step-down DC/DC converter capable of providing up to 12.5A of output current from a 2.25V to 5.5V input supply. The device employs Silent Switcher 2 architecture with internal hot loop bypass capacitors to achieve both low EMI and high efficiency at switching frequencies as high as 5MHz. For systems with higher power requirements, multi-phasing parallel converters is readily implemented.

The LTC3311S uses a constant frequency, peak current mode control architecture for fast transient response. A 500mV reference allows for low voltage outputs. 100% duty cycle operation delivers low drop out.

Other features include a power good signal when the output is in regulation, precision enable threshold, output overvoltage protection, thermal shutdown, a temperature monitor, clock synchronization, mode selection and output short circuit protection. The device is available in a compact 18-lead 3mm × 3mm LQFN package.

APPLICATIONS

Automotive/Industrial/Communications
Servers, Telecom Power Supplies
Distributed DC Power Systems (POL)
FPGA, ASIC, μP Core Supplies

Product Categories

Power Management
- Internal Power Switch Buck Regulators
- Ultralow Noise Regulators

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Product Lifecycle Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (1)

DC3018A

LTC3311S Demo Board | 3.3V to 1.2V at 12.5A, 2MHz Low EMI Buck Regulator in a 1.17cm2 Solution

DC3018A

View Detailed Evaluation Kit Information

Demonstration Circuit 3018A features the LTC3311S 12.5A, low voltage, synchronous step-down Silent Switcher^™ 2 operating as a 2MHz 3.3V to 1.2V 12.5A buck regulator. The LTC3311S supports output voltages from 0.5V to V_IN with operating frequencies from 500kHz up to 5MHz. The LTC3311S is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic step-down switching regulator. The integrated bypass capacitors optimize all the fast current loops and make it easier to minimize EMI/EMC emissions by reducing layout sensitivity. Fast minimum on-time of 35ns enables high V_IN to low V_OUT conversion at high frequency.

DC3018A is set up to run in forced continuous mode with a 2MHz switching frequency but can be configured to pulse skip mode or different switching frequencies. RT is connected to V_IN which sets the MODE/SYNC pin as an input and allows the LTC3311S to sync from an external clock. Connecting the MODE/SYNC pin to V_IN sets the mode to pulse skip mode and connecting the MODE/SYNC pin to GND sets the mode to forced continuous mode. The Efficiency vs Load graph shows the efficiency and the power loss of the circuit with a 3.3V input in forced continuous mode operation.

The DC3018A also has an EMI filter to reduce conducted EMI. This EMI filter can be included by applying the input voltage at the VIN EMI terminal. The EMI performance of the board is shown in the EMI Test Results section. The red lines in the EMI performance graphs illustrate the CISPR25 Class 5 peak limits for the conducted and radiated emission tests.

The LTC3311S data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with the demo manual. The LTC3311S is assembled in a 3mm × 3mm LQFN package with exposed pads for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout.

Resources

Documentation & Resources

Data Sheets

LTC3311S 5V, 12.5A Synchronous Step-Down Silent Switcher 2 in 3mm x 3mm LQFN Data Sheet (Rev. A)
1/12/2021
PDF

Reliability Data

R523 Reliability Data
4/13/2020
PDF

Webcasts

Improving Switch-Mode Power Supplies Using Noise Cancelling Technology
2/8/2023

Books & eBooks

Understanding Silent Switcher Technology: High Efficiency, Low EMI eBook
7/14/2023
PDF

Solutions Bulletins & Brochures

Silent Switcher Technology
8/15/2023
PDF

Technical Articles

How to Minimize the Number, and Size, of Output Capacitors in Your Power Supply Design
9/1/2021

Rarely Asked Questions

Point-of-Load DC-to-DC Converters Solve Voltage Accuracy, Efficiency, and Latency Issues
7/1/2021

Tools & Simulations

LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

LTspice downloads and documentation

Models for the following parts are available in LTspice:

LTC3311

LTC3311-0.75

LTC3311-0.85

LTC3311-0.875

LTC3311-1

LTC3311S

LTpowerCAD

LTpowerCAD^® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

To open the project file for this circuit:

Step 1: Download and install LTpowerCAD on your computer.

Step 2: Click on the link(s) in the section below to download part-specific project files.

Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.

LTpowerCAD download and documentation

LTpowerCAD Project Files

LTC3311S Project - 3.3Vin to 1.2Vout/12.5A, 2MHz

Design tools for the following parts are available in LTpowerCAD:

LTC3311S

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number	Material Declaration	Reliability Data	Pin/Package Drawing	CAD Symbols, Footprints & 3D Models
LTC3311SEV#PBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SEV#TRMPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SEV#TRPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#PBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#TRMPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#TRPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#WPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#WTRMPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
LTC3311SIV#WTRPBF	Material Declaration	Reliability Data	18-Lead LQFN (3mm × 3mm × 0.94mm)	Ultra Librarian SamacSys
Wafer Fabrication Data		R523 Reliability Data

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Support & Discussions

LTC3311S Discussions

LTspice FRA feature

12 week(s) ago in LTspice

question about the fra feature in LTspice

21 week(s) ago in LTspice

RE: Dead Time ,Rise and fall time of LTC3311

All LTC3311S Discussions

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.