LT3909

RECOMMENDED FOR NEW DESIGNS

2-String × 60mA, 2MHz Step-Up LED Driver with ±2% Current Matching

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Overview

  • Up to 36V of LEDs, 2-String × 60mA LED Driver
  • Wide Input Range: 2.9V to 40V
  • Up to 40,000:1 PWM Dimming (250ns LED On-Time) (Independent of Leakage at VOUT)
  • ±2% LED Current Matching (Typ ±0.3%)
  • Integrated Schottky Diode
  • Internal 400mΩ, 40V, 1A Switch
  • Single Resistor Sets LED Current (10mA to 60mA) for Both High-Side Current Sources
  • Output Adapts to LED VF for Optimum Efficiency
  • LED Current Regulated Even for VIN > VOUT
  • Fault Flag + Protection for Open-LED and LED-Short-to- GND (Other String Remains in Regulation)
  • Programmable Maximum VOUT (Regulated)
  • Internal Compensation, Soft-Start and Thermal Regulation
  • Accurate EN/UVLO Threshold
  • Fixed 2MHz Switching Frequency
LT3909
2-String × 60mA, 2MHz Step-Up LED Driver with ±2% Current Matching
2-String × 40mA, 2MHz LED Driver for Ten White LEDs/String LED Current Waveforms 20,000:1 PWM Dimming (100Hz) Product Package 1 Product Package 2
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Documentation

Data Sheet 1

User Guide 1

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
Ideal Diodes and PowerPath Controllers 1
LTC4417
RECOMMENDED FOR NEW DESIGNS Prioritized PowerPath™ Controller
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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LT3909
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Evaluation Kits

eval board
schematic 1
DC2176A

LT3909EDD Demo Board | 2-String Boost LED Driver, 7V ≤ VIN ≤ 36V, VLED up to 35V @ 50mA (x2)

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Product Details

Demonstration circuit 2176A features the LT3909, a 2-string × 50mA, 2MHz step-up LED driver with ±1.8% current matching. The LT3909 precisely regulates two LED strings for equal current, supports LED dimming that reduces brightness down to a 1/40,000 ratio, protects against faults and also reports faults. The LT3909 consists of a step-up converter with a fixed 2MHz switching frequency and current sources for the LED strings.


The maximum current in each LED string is 40mA. The ISET resistor can be changed to 20.0kΩ to program the string current to 50mA – see the data sheet for an application example with 50mA string current. Voltage feedback resistors optimize operation for LEDs that are 35V maximum. 


 
DC2176A
LT3909EDD Demo Board | 2-String Boost LED Driver, 7V ≤ VIN ≤ 36V, VLED up to 35V @ 50mA (x2)
DC2176A - Schematic

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