LT3744 - High Current Synchronous Step-Down LED Driver

Features

  • Ideal for Driving Up to 40A LEDs
  • Up to 3000:1 PWM Dimming
  • 20:1 Analog Dimming
  • ±3% Current Regulation Accuracy
  • ±3% Voltage Regulation Accuracy
  • Unique Inverting Buck-Boost Topology Allows Grounded Heat Sink to Be Used for RGB LEDs
  • 3.3V to 36V Input Voltage Range
  • Peak Current Mode with DC LED Current Sensing
  • Open and Shorted LED Protection and Fault Reporting
  • Floating LED Driver Allows Single Power Solution to Drive Multicolor LEDs or Single LED with Three Different Regulated Currents
  • Thermally Enhanced 5mm × 6mm QFN 36-Lead Package

Typical Application

LT3744 Typical Application
LT3744 Typical Application

Description

The LT®3744 is a fixed frequency synchronous step-down DC/DC controller designed to drive a LED load at up to 20A continuous or 40A pulsed. The peak current mode controller will maintain ±3% LED current regulation over a wide output voltage range, from VEE to VIN. By allowing VEE to float to negative voltages, several LEDs in series can be driven from a single Li-Ion battery with a simple, single step-down output stage. PWM dimming is achieved with the PWM pins. The regulated LED current is set with analog voltages at the CTRL pins. Regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. The switching frequency is programmable from 100kHz to 1MHz through an external resistor on the RT pin.

Additional features include an accurate external reference voltage, a control input for thermally derating regulation current, an accurate EN/UVLO pin, an open-drain output fault flag, OVLO, frequency synchronization, and thermal shutdown.

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
LT3744EUHE#PBF 5x6 QFN-36 UHE E 05-08-1876 Yes
LT3744EUHE#TRPBF 5x6 QFN-36 UHE E 05-08-1876 Yes
LT3744IUHE#PBF 5x6 QFN-36 UHE I 05-08-1876 Yes
LT3744IUHE#TRPBF 5x6 QFN-36 UHE I 05-08-1876 Yes


LT3744 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
LT3744EUHE#PBF 5x6 QFN-36 E $5.64 $3.95 Yes
LT3744EUHE#TRPBF 5x6 QFN-36 E $4.01 Yes
LT3744IUHE#PBF 5x6 QFN-36 I $7.07 $4.95 Yes
LT3744IUHE#TRPBF 5x6 QFN-36 I $5.01 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
DC1930A LT3744 Demo Board | Inverting Buck-Boost LED Driver, 3.3V ≤ VIN ≤ 30V, Drives 3 LEDs @ up to 12A $249.00
DC2339A LT3744 Demo Board | Sync Buck LED Driver, 5.5V ≤ VIN ≤ 24V, Drives 3 LEDs @ up to 20A Each $175.00
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Click here to view our complete list of demo boards

Applications

  • LED Driver for DLP Projectors
  • Heads-Up Displays
  • High Power LED

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:
LT3744

Technical Support