LT3474
LT3474-1

PRODUCTION

Step-Down 1A LED Driver

Part Models
8
1ku List Price
Starting From $3.54
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Part Details

  • 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
LT3474
LT3474-1
Step-Down 1A LED Driver
Step-Down 1A LED Driver Efficiency Product Package 1
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Documentation

Data Sheet

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

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Hardware Ecosystem

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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.


Evaluation Kits

eval board
DC842A

LT3474EFE/IFE Demo Board | Step-Down LED Driver, 6V ≤ VIN ≤ 36V, VLED = 3.9V @ 1A

Product Details

Demonstration circuit 842 features the LT3474 constant frequency 1A step-down LED driver in a compact 16-lead TSSOP thermally enhanced package. The demonstration circuit is designed to drive a single Lumileds Luxeon III star white LED (included on the board) from a wide 6V to 36V input voltage range. The typical LED forward voltage at 1A is 3.9V.


The high switching frequency scheme permits the use of small inductors and ceramic capacitors to save space and cost. The current mode PWM scheme provides fast transient response and cycle-by-cycle current limiting. Frequency foldback and thermal shutdown provide additional protection.

eval board
DC1309A

LT3474EFE-1 Demo Board | Buck LED Driver, 4 ≤ VIN ≤ 36V, VLED up to 26V @ 1A

Product Details

Demonstration circuit 1309 features the LT3474-1 36V step-down 1A LED driver. The demonstration circuit is designed to drive a string of 1A LEDs from a high input voltage. The LT3474-1 operates with a 4V to 36V input voltage range and maintains high LED current accuracy from 35mA to 1A. The LT3474-1 can be dimmed with its analog CTRL pin or with a PWM dimming input signal. A few simple modifications can be made to DC1309 in order to add PWM dimming to the circuit.

An external overvoltage protection clamp provides open LED protection and is set to about 24V on DC1309A. The level of the clamp can be changed by replacing the zener diode (D4) with a different zener diode. The LT3474-1 differs from the LT3474 in its output voltage capability. The LT3474 has a 13V clamp that does not allow the use of an LED string of greater than 13V on the output. However, LT3474-1 does not have this clamp and it can power LEDs up to 26V, as long as the external clamp is adjusted correctly.

DC842A
LT3474EFE/IFE Demo Board | Step-Down LED Driver, 6V ≤ VIN ≤ 36V, VLED = 3.9V @ 1A
DC842A - Schematic
DC1309A
LT3474EFE-1 Demo Board | Buck LED Driver, 4 ≤ VIN ≤ 36V, VLED up to 26V @ 1A
DC1309A - Schematic

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