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LT3474: Step-Down 1A LED Driver Data Sheet10/14/2008
Overview
Features and Benefits
- True Color PWM™ Delivers Constant Color with 400:1 Dimming Range
- Wide Input Range: 4V to 36V
- Up to 1A LED Current
- Adjustable 200kHz–2MHz Switching Frequency
- Adjustable Control of LED Current
- Integrated Boost Diode
- High Output Current Accuracy is Maintained Over a Wide Range from 35mA to 1A
- Open LED (LT3474) and Short-Circuit Protection
- High Side Sense Allows Grounded Cathode Connection
- Uses Small Inductors and Ceramic Capacitors
- LT3474-1 Drives LED Strings Up to 26V
- Compact 16-Lead TSSOP Thermally Enhanced Surface Mount Package
Product Details
The LT3474/LT3474-1 are fixed frequency step-down DC/DC converters designed to operate as constant-current sources. An internal sense resistor monitors the output current allowing accurate current regulation, ideal for driving high current LEDs. High output current accuracy is maintained over a wide current range, from 35mA to 1A, allowing a wide dimming range.
Unique PWM circuitry allows a dimming range of 400:1, avoiding the color shift normally associated with LED current dimming.
The high switching frequency offers several advantages, permitting the use of small inductors and ceramic capacitors. Small inductors combined with the 16 lead TSSOP surface mount package save space and cost versus alternative solutions. The constant switching frequency combined with low-impedance ceramic capacitors result in low, predictable output ripple.
With their wide input range of 4V to 36V, the LT3474/ LT3474-1 regulate a broad array of power sources, from 5V logic rails to unregulated wall transformers, lead acid batteries and distributed power supplies. A current mode PWM architecture provides fast transient response and cycle-by-cycle current limiting. Frequency foldback and thermal shutdown provide additional protection.
Applications
- Automotive and Avionic Lighting
- Architectural Detail Lighting
- Display Backlighting
- Constant Current Sources
Product Categories
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 (2)
Documentation & Resources
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R303 Reliability Data3/23/2018
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DC842A - Demo Manual9/24/2009
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DC1309A - Demo Manual9/24/2009
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.
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:
LT3474
LT3474-1
Product Recommendations
LT3474 Companion Parts
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 |
|---|---|---|---|---|
| LT3474EFE#PBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474EFE#TRPBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474EFE-1#PBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474EFE-1#TRPBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474IFE#PBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474IFE#TRPBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474IFE-1#PBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| LT3474IFE-1#TRPBF | Material Declaration | Reliability Data | 16-Lead TSSOP w/ EP | |
| Wafer Fabrication Data | R303 Reliability Data |
PCN-PDN Information
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Support & Discussions
LT3474 Discussions
Sample & Buy
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Evaluation Boards
Pricing displayed is based on 1-piece.
Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
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.