LT3909 Series

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

Catalog

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

Part	Dimming	Operating Temperature [Min]	Operating Temperature [Max]	Supplier Device Package	Type	Voltage - Output	Grade	Current - Output / Channel	Number of Outputs	Mounting Type	Package / Case	Package / Case	Frequency	Voltage - Supply (Max) [Max]	Voltage - Supply (Min) [Min]	Topology
Analog Devices LT3909EMSE#TRPBF	Analog PWM	-40 °C	125 ¯C	12-MSOP-EP	DC DC Regulator	40 V	Automotive	50 mA	2	Surface Mount	12-TSSOP Exposed Pad	0.118 in 3 mm	2 MHz	40 V	2.9 V	Step-Up (Boost)
Analog Devices LT3909IMSE#PBF	Analog PWM	-40 °C	125 ¯C	12-MSOP-EP	DC DC Regulator	40 V	Automotive	50 mA	2	Surface Mount	12-TSSOP Exposed Pad	0.118 in 3 mm	2 MHz	40 V	2.9 V	Step-Up (Boost)
Analog Devices LT3909IDD#TRPBF	Analog PWM	-40 °C	125 ¯C	12-DFN (3x3)	DC DC Regulator	40 V	Automotive	50 mA	2	Surface Mount	12-WFDFN Exposed Pad		2 MHz	40 V	2.9 V	Step-Up (Boost)

Catalog

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

Key Features

• 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 VFfor 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

Description

The LT3909 is a 2-string × 60mA LED driver with a fixed 2MHz step-up DC/DC converter capable of driving up to 36V of LEDs. Each LED string contains an accurate high-side current source with ±2% current matching. Output voltage adapts to variations in LED VFfor optimum efficiency.Maximum LED current can be programmed from 10mA to 60mA per string using a single resistor. LED brightness can be reduced with analog dimming (up to 10:1) or with PWM dimming (up to 40,000:1 at 100Hz, up to 160:1 at 25kHz) (independent of leakage at VOUT). The LED pins can be paralleled for higher LED current.Additional features include: programmable maximum VOUTfor open LED protection, a fault flag to indicate open-LED or LED-short-to-GND and an internal regulation loop to safely limit junction temperature. The LT3909 also includes internal compensation, internal soft-start and micropower shutdown. The LT3909 is available in the 12-pin (3mm × 3mm) DFN and 12-pin MSOP packages.ApplicationsPDAs, Handheld ComputersGPS ReceiversAutomotive DisplaysHigh Contrast Instrument Clusters