LT3514 - Triple Step-Down Switching Regulator with 100% Duty Cycle Operation

Features

  • Wide Input Voltage Range: 3.2V to 36V
    (40V Transient)
  • Three Outputs: 2A, 1A, 1A
  • 100% Duty Cycle Operation
  • Resistor-Programmed Constant Frequency
  • Short-Circuit Robust
  • Wide SYNC Range: 350kHz to 2.2MHz
  • Anti-Phase Switching Reduces Ripple
  • Feedback Voltage: 800mV
  • Independent Run/Soft-Start Pins
  • Shutdown with UVLO
  • Internal Compensation
  • Thermal Shutdown
  • Tiny 28-Lead (4mm × 5mm) Thermally Enhanced QFN Package
  • 24-Lead Exposed Pad TSSOP

Typical Application

LT3514 Typical Application
LT3514 Typical Application

Description

The LT®3514 consists of three buck regulators (2A, 1A, 1A output current). The device has a wide operating input range of 3.2V to 36V. An on-chip boost regulator allows each channel to operate up to 100% duty cycle. The LT3514 is designed to minimize external component count and results in a simple and small application circuit.

The LT3514 operates robustly in fault conditions. Cycleby- cycle peak current limit and catch diode current limit sensing protect the IC during overload conditions. Thermal shutdown protects the power switches at elevated temperatures. Soft-start helps control the peak inductor current during startup.

The LT3514 also features output voltage tracking and sequencing, programmable frequency, programmable undervoltage lockout, and a power good pin to indicate when all outputs are in regulation.

The LT3514 has one fewer channel (CH2) than the LT3504, and has one channel (CH3) that outputs 2A instead of 1A. The LT3514 in QFN is pin compatible with the LT3504. The LT3504 provides four 1A outputs.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT3514EFE#PBF TSSOP-24 FE E 05-08-1771 Yes
LT3514EFE#TRPBF TSSOP-24 FE E 05-08-1771 Yes
LT3514EUFD#PBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT3514EUFD#TRPBF 4x5 QFN-28 UFD E 05-08-1712 Yes
LT3514IFE#PBF TSSOP-24 FE I 05-08-1771 Yes
LT3514IFE#TRPBF TSSOP-24 FE I 05-08-1771 Yes
LT3514IUFD#PBF 4x5 QFN-28 UFD I 05-08-1712 Yes
LT3514IUFD#TRPBF 4x5 QFN-28 UFD I 05-08-1712 Yes


LT3514 Package Drawing
LT3514 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3514EFE#PBF TSSOP-24 E $5.36 $3.75 Yes
LT3514EFE#TRPBF TSSOP-24 E $3.81 Yes
LT3514EUFD#PBF 4x5 QFN-28 E $5.00 $3.50 Yes
LT3514EUFD#TRPBF 4x5 QFN-28 E $3.56 Yes
LT3514IFE#PBF TSSOP-24 I $5.90 $4.13 Yes
LT3514IFE#TRPBF TSSOP-24 I $4.19 Yes
LT3514IUFD#PBF 4x5 QFN-28 I $5.50 $3.85 Yes
LT3514IUFD#TRPBF 4x5 QFN-28 I $3.91 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1980A LT3514 Demo Board | 5.4V to 36VIN, Triple Output; VOUT1 = 5V @ 1A, VOUT2 = 3.3V @ 2A, VOUT3 = 1.8V @ 1A $175.00
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Click here to view our complete list of demo boards

Applications

  • Automotive Battery Regulation
  • Industrial Control Supplies
  • Wall Transformer Regulation
  • Distributed Supply Regulation

Product Notifications

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT3514

Technical Support