LT3475
LT3475-1

PRODUCTION

Dual Step-Down 1.5A LED Driver

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Overview

  • True Color PWM™ Delivers Constant Color with 3000:1 Dimming Range
  • Wide Input Range: 4V to 36V Operating, 40V Maximum
  • Accurate and Adjustable Control of LED Current from 50mA to 1.5A
  • High Side Current Sense Allows Grounded Cathode LED Operation
  • Open LED (LT3475) and Short Circuit Protection
  • LT3475-1 Drives LED Strings Up to 25V
  • Accurate and Adjustable 200kHz to 2MHz Switching Frequency
  • Anti-Phase Switching Reduces Ripple
  • Uses Small Inductors and Ceramic Capacitors
  • Available in the Compact 20-Lead TSSOP Thermally Enhanced Surface Mount Package

The LT3475 is a dual step-down DC/DC converter designed to operate as a constant-current source. An internal sense resistor monitors the output current allowing accurate current regulation ideal for driving high current LEDs. The high side current sense allows grounded cathode LED operation. High output current accuracy is maintained over a wide current range, from 50mA to 1.5A, allowing a wide dimming range. Unique PWM circuitry allows a dimming range of 3000:1, 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 LT3475's 20 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 its wide input range of 4V to 36V, the LT3475 regulates a broad array of power sources. 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
LT3475
LT3475-1
Dual Step-Down 1.5A LED Driver
Dual Step-Down 1.5A LED Driver Efficiency Product Package 1
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 2

Design Note 2

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Circuit Monitors 1
LT2940
PRODUCTION Power and Current Monitor
Pulse-Width Modulation (PWM) & Pulse Generators 1
LTC6992
TimerBlox: Voltage-Controlled Pulse Width Modulator (PWM)
Temperature Sensors 1
LTC2997
PRODUCTION Remote/Internal Temperature Sensor
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Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

  • LT3475
  • LT3475-1
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.

Evaluation Kits

eval board
schematic 6
schematic 7
schematic 8
schematic 9
schematic 10
DC1315A

LT3475IFE-1 Demo Board | Dual Step-Down LED Driver, 4V ≤ VIN ≤ 36V, VOUT up to 13V @ 1.5A (x2)

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Product Details

Demonstration circuit 1315 features the LT3475-1 dual step-down 1.5A LED driver in a 16-lead TSSOP thermally enhanced package. The demonstration circuit is designed to drive two 1.5A 4-LED strings (one on each channel) from an input voltage between 13V and 36V, but the start-up voltage is limited to 30V. The LT3475-1 operates from 4V to 36V so a lower input voltage can be applied with fewer LEDs. 
DC923A
LT3475 Demo Board
DC923A Demo Board DC923A Demo Board DC923A Demo Board DC923A Demo Board DC923A - Schematic
DC1315A
LT3475IFE-1 Demo Board | Dual Step-Down LED Driver, 4V ≤ VIN ≤ 36V, VOUT up to 13V @ 1.5A (x2)
DC1315A Demo Board DC1315A Demo Board DC1315A Demo Board DC1315A Demo Board DC1315A - Schematic

Latest Discussions

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