Features and Benefits
- PWM Dimming Provides Up to 3000:1 Dimming Ratio
- CTRL_SEL Dimming Provides Up to 3000:1 Dimming Ratio Between Any Current
- Three-State Current Control for Color Mixing
- ±6% Current Regulation Accuracy
- 6V to 36V Input Voltage Range
- Average Current Mode Control
- 2μs Maximum Recovery Time Between Any Current Regulation State
- <1μA Shutdown Current
- Output Voltage Regulation and Open-LED Protection
- Thermally Enhanced 4mm × 5mm QFN and 28-Pin FE Package
The LT3743 is a fixed frequency synchronous step-down DC/DC controller designed to drive high current LEDs. The average current mode controller will maintain inductor current regulation over a wide output voltage range of 0V to (VIN – 2V). LED dimming is achieved through analog dimming on the CTRL_L, CTRL_H and CTRL_T pins and with PWM dimming on the PWM and CTRL_SEL pins. Through the use of externally switched load capacitors, the LT3743 is capable of changing regulated LED current levels within several μs, providing accurate, high speed PWM dimming between two current levels. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin.
Additional features include voltage regulation and overvoltage protection set with a voltage divider from the output to the FB pin. Overcurrent protection is provided and set by the CTRL_H pin.
- DLP Projectors
- High Power Architectural Lighting
- Laser Diodes
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 1470 is a High Current Synchronous Step-Down LED Driver with Three-State Control featuring the LT3743EUFD. The demo board is optimized for 20A output from a 12V input. Being an LED driver, the output current is regulated until the output voltage reaches a programmed voltage limit. The voltage limit on this demo board is set to around 6V by resistors R5 and R6. The 6V is chosen because of the 6.3V voltage rating of the output capacitors.
The ideal load to be used with this demo board is a single LED, such as PT120 from Luminus Devices. The input voltage range of the LT3743 is 6V to 36V; however, the demo board utilizes 30V MOSFETs to demonstrate best efficiency, so the maximum recommended input voltage is 24V for the demo board.
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
Press Releases (1)
Technical Articles (2)
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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.