Product Details Supplier Info More products
3909

Linear Technology has announced the LT3909, a high efficiency, constant current LED driver that can drive two strings of up to 10 LEDs at 50mA. To ensure constant brightness, each LED string contains an accurate high side current source with ±1.8 per cent current matching. Its input voltage range of 2.9V to 40V makes it ideal for applications ranging from single/multiple Li-Ion inputs to automotive and industrial applications.

The LT3909 offers PWM dimming ratios up to 40,000:1, providing an LED backlighting solution in applications such as automotive and avionic displays subject to a wide range of ambient lighting conditions. The LT3909 delivers up to 36V of LEDs per string, and its output voltage adapts to any variation in LED VF for optimum efficiency. Although designed to drive LEDs in a boost topology, LED current is accurately regulated even when VIN is greater VOUT. The LT3909 operates at a constant switching frequency of 2MHz, enabling the use of very small externals while avoiding critical frequency bands such as AM radio in automotive applications. The combination of its tiny externals and 3mm x 3mm DFN (or MSOP-12E) package offers a very compact solution footprint for LED applications requiring two strings of 50mA LEDs.

The LT3909 utilises an internal 400mΩ, 40V, 1A switch with an integrated Schottky diode on-chip, eliminating both the added cost and space required of an external diode. A unique high side LED current sense topology enables the LED cathode to be connected directly to ground, creating a single wire current source. A single resistor sets LED current from 10mA to 50mA for both high side current sources. The LT3909 offers both open and shorted LED protection with a fault flag to indicate these conditions. Even if one LED string experiences an open-LED or short-to-GND failure, the other string will remain in regulation. Other features include internal compensation, soft-start and micropower shutdown.

The LT3909EDD is available in a 12-lead 3mm x 3mm DFN package and the LT3909EMSE is available in a thermally enhanced 12-lead MSOP package. Industrial temperature versions, the LT3909IDD and LT3909IMSE, are tested and guaranteed to operate from a –40°C to 125°C operating junction temperature. High temperature versions, the LT3909HDD and LT3909HMSE, are tested and guaranteed to operate from a –40°C to 150°C operating junction temperature.  Pricing starts at $2.50 each for 1,000-piece quantities and all versions are available from stock

Linear Technology

Linear Technology Corporation, a member of the S&P 500, designs, manufactures and markets a broad line of high-performance analogue-integrated circuits for major communications, computer and industrial companies worldwide.

Linear Technology Corporation, a member of the S&P 500, designs, manufactures and markets a broad line of high-performance analogue-integrated circuits for major communications, computer and industrial companies worldwide.

Linear (or analogue) circuits provide an essential bridge between our analog world and the digital microelectronics used in consumer products, wireless communications, networking products, computers, medical electronics, factory automation and automotive electronics.

Linear Technology provides customers with high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC/DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits and many other analogue functions.

The company markets over 7,500 products to more than 15,000 original equipment manufacturers. These products compete in the marketplace based on their performance, functional value, quality and reliability. Linear Technology products are produced using state-of-the-art silicon gate CMOS, BiCMOS, complementary bipolar, high-voltage and RF wafer-fabrication process technologies.

Linear Technology, headquartered in Milpitas, California, employs 4,100 people worldwide and has technical sales and support locations throughout North America, Europe and Asia. In addition to manufacturing, assembly and test facilities in California, Washington, Singapore and Malaysia, the company has 12 design centers in Arizona, California (3), Colorado, Vermont, Massachusetts, New Hampshire, North Carolina, Texas, Singapore, and Munich, Germany.

View full profile