LT3909 - 2-String × 60mA, 2MHz Step-Up LED Driver with ±2% Current Matching
- 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
The LT®3909 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 VF for 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 VOUT for 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.
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 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
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Demo BoardsLinear 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.
|DC2176A||LT3909EDD Demo Board | 2-String Boost LED Driver, 7V ≤ VIN ≤ 36V, VLED up to 35V @ 50mA (x2)||$199.00|
- PDAs, Handheld Computers
- GPS Receivers
- Automotive Displays
- High Contrast Instrument Clusters
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