LT3474/LT3474-1 - Step-Down 1A LED Driver
Features
- 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
AEC-Q100 data available for specific packages
Typical Application
Description
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.
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 |
|---|---|---|---|---|---|
| LT3474EFE-1#PBF | TSSOP-16 | FE | E | 05-08-1663 (BA) | Yes |
| LT3474EFE-1#TRPBF | TSSOP-16 | FE | E | 05-08-1663 (BA) | Yes |
| LT3474EFE#PBF | TSSOP-16 | FE | E | 05-08-1663 (BA) | Yes |
| LT3474EFE#TRPBF | TSSOP-16 | FE | E | 05-08-1663 (BA) | Yes |
| LT3474IFE-1#PBF | TSSOP-16 | FE | I | 05-08-1663 (BA) | Yes |
| LT3474IFE-1#TRPBF | TSSOP-16 | FE | I | 05-08-1663 (BA) | Yes |
| LT3474IFE#PBF | TSSOP-16 | FE | I | 05-08-1663 (BA) | Yes |
| LT3474IFE#TRPBF | TSSOP-16 | FE | I | 05-08-1663 (BA) | Yes |
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 | |
|---|---|---|---|---|---|---|
| LT3474EFE-1#PBF | TSSOP-16 | E | $4.22 | $2.95 | Yes | |
| LT3474EFE-1#TRPBF | TSSOP-16 | E | $3.01 | Yes | ||
| LT3474EFE#PBF | TSSOP-16 | E | $4.21 | $2.95 | Yes | |
| LT3474EFE#TRPBF | TSSOP-16 | E | $3.07 | Yes | ||
| LT3474IFE-1#PBF | TSSOP-16 | I | $5.06 | $3.54 | Yes | |
| LT3474IFE-1#TRPBF | TSSOP-16 | I | $3.60 | Yes | ||
| LT3474IFE#PBF | TSSOP-16 | I | $5.06 | $3.54 | Yes | |
| LT3474IFE#TRPBF | TSSOP-16 | I | $3.66 | Yes | ||
| Buy Now • Request Samples | ||||||
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 |
|---|---|---|---|
| DC1309A | LT3474EFE-1 Demo Board | Buck LED Driver, 4 ≤ VIN ≤ 36V, VLED up to 26V @ 1A | $100.00 | |
| DC842A | LT3474EFE/IFE Demo Board | Step-Down LED Driver, 6V ≤ VIN ≤ 36V, VLED = 3.9V @ 1A | $100.00 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT3474IFE-1#PBF | TSSOP-16 | I | $5.06 | $3.54 | Yes | |
| LT3474IFE-1#TRPBF | TSSOP-16 | I | $3.60 | Yes | ||
| LT3474IFE#PBF | TSSOP-16 | I | $5.06 | $3.54 | Yes | |
| LT3474IFE#TRPBF | TSSOP-16 | I | $3.66 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Automotive and Avionic Lighting
- Architectural Detail Lighting
- Display Backlighting
- Constant Current Sources
People Who Viewed This Product Also Viewed
- LTM8042/LTM8042-1 - μModule (Power Module) Boost LED Driver and Current Source
- LT3517 - Full-Featured LED Driver with 1.5A Switch Current
- LT3478 - 4.5A Monolithic LED Drivers with True Color PWM Dimming
- LT3477 - 3A, DC/DC Converter with Dual Rail-to-Rail Current Sense
- LTM8040 - 36V, 1A μModule (Power Module) LED Driver and Current Source
- LT3761/LT3761-1 - 60VIN LED Controller with Internal PWM Generator
- LT3518 - Full-Featured LED Driver with 2.3A Switch Current
- LT3796/LT3796-1 - 100V Constant-Current and Constant-Voltage Controller with Dual Current Sense
- LT1618 - Constant-Current/Constant-Voltage 1.4MHz Step-Up DC/DC Converter
- LT3475/LT3475-1 - Dual Step-Down 1.5A LED Driver
Product Notifications
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.
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:
LT3474
LT3474-1
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
