The LT3491 is a fixed frequency step-up DC/DC converter specifically designed to drive up to six white LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The device features a unique high side LED current sense that enables the part to function as a ?one wire current source;? one side of the LED string can be returned to ground anywhere, allowing a simpler one wire LED connection. Traditional LED drivers use a grounded resistor to sense LED current, requiring a 2-wire connection to the LED string.The 2.3MHz switching frequency allows the use of tiny inductors and capacitors. A single pin performs both shutdown and accurate LED dimming control. Few external components are needed: open-LED protection and the Schottky diode are all contained inside the tiny SC70 package. With such a high level of integration, the LT3491 provides a high efficiency LED driver solution in the smallest of spaces.Applications Cellular Phones PDAs, Handheld Computers Digital Cameras MP3 Players GPS Receivers

Demonstration circuit DC915 features the LT3466-1 high efficiency boost white LED driver and a step-up converter. There is one LED driver output for 6 or 8 WLEDs and a separate DC/DC converter that generates outputs for the LCD bias. VO1 drives 8 LEDs in series with 15mA LED current and VO2/VO3 can delivery ±15V at 10mA current. If the charge-pump circuitry which generates VO3 is removed (C4, C5 and D1), VO2 can deliver over 35mA of current. The input voltage range is 3V to 14V, but can go as low as 2.7V with slightly reduced output current.

The LT3478/LT3478-1 are 4.5A step-up DC/DC converters designed to drive LEDs with a constant current over a wide programmable range. Series connection of the LEDs provides identical LED currents for uniform brightness without the need for ballast resistors and expensive factory calibration.The LT3478-1 reduces external component count and cost by integrating the LED current sense resistor. The LT3478 uses an external sense resistor to extend the maximum programmable LED current beyond 1A and also to achieve greater accuracy when programming low LED currents. Operating frequency can be set with an external resistor from 200kHz up to 2.25MHz. Unique circuitry allows a PWM dimming range up to 3000:1 while maintaining constant LED color. The LT3478/LT3478-1 are ideal for high power LED driver applications such as automotive TFT LCD backlights, courtesy lighting and heads-up displays. One of two CTRL pins can be used to program maximum LED current. The other CTRL pin can be used to program a reduction in maximum LED current vs temperature to maximize LED usage and improve reliability.Additional features include inrush current protection, programmable open LED protection and programmable soft-start. Each part is available in a 16-pin thermally enhanced TSSOP Package.Applications High Power LED Driver Automotive Lighting

Demonstration circuit 986 is a Triple Step-Down LED Driver featuring the LT3496EUFD. The LT3496 is a triple output DC/DC converter designed to operate as current sources for driving high current LEDs. Each ofthe three regulators on the demo board is independently operated. The default current for each output channel is 500mA. The output current should not exceed the rated current of the LEDs used.  The maximum voltage of an LED string the demo board can drive is limited by the duty cycle and the input voltage of the LT3496. The maximum power input voltage (PVIN ) is 45V. As a result, each channel of the demo board can drive up to ~31V total LED voltage. The LT3496's input voltage range is 3V to 30V (with 40V transients), however to minimize power dissipation the demo board uses a 3V to 5.5V supply.

LED Lighting Drivers 1.0A LED Flash Driver

600mA Universal Multi-Output LED/CAM Driver Features: Low Noise, Multi-Mode Charge Pump (1x, 1.5x, 2x) Provides Up to 91% Efficiency Slew Limited Switching Reduces Conducted and Radiated Noise (EMI) Up to 600mA Total Output Current Twelve 28mA Universal Current Sources with 64-Step Linear Brightness Control 425mA CAM LED Current Source with 16-Step Linear Brightness Control and 2-Second High Current Safety Timer Independent On/Off, Brightness Level, Blinking and Gradation Control for Each Current Source Using 2-Wire I2C Interface Internal Current Reference Two I2C Addresses are Available (LTC3207 00110110, LTC3207-1 00110100) Configurable ENU Pin for Asynchronous LED On/Off Control Automatic or Forced Mode Switching Internal Soft-Start Limits Inrush Current Short-Circuit/Thermal Protection 4mm × 4mm 24-Pin QFN Plastic Package

600mA Universal Multi-Output LED/CAM Driver Features: Low Noise, Multi-Mode Charge Pump (1x, 1.5x, 2x) Provides Up to 91% Efficiency Slew Limited Switching Reduces Conducted and Radiated Noise (EMI) Up to 600mA Total Output Current Twelve 28mA Universal Current Sources with 64-Step Linear Brightness Control 425mA CAM LED Current Source with 16-Step Linear Brightness Control and 2-Second High Current Safety Timer Independent On/Off, Brightness Level, Blinking and Gradation Control for Each Current Source Using 2-Wire I2C Interface Internal Current Reference Two I2C Addresses are Available (LTC3207 00110110, LTC3207-1 00110100) Configurable ENU Pin for Asynchronous LED On/Off Control Automatic or Forced Mode Switching Internal Soft-Start Limits Inrush Current Short-Circuit/Thermal Protection 4mm × 4mm 24-Pin QFN Plastic Package

LED Lighting Drivers 4 Channel High Current LED Driver with Adaptable Power Control

The LT3799 is an isolated flyback controller with power factor correction specifically designed for driving LEDs. The controller operates using critical conduction mode allowing the use of a small transformer. Using a novel current sensing scheme, the controller is able to deliver a well regulated current to the secondary side without using an opto-coupler. A strong gate driver is included to drive an external high voltage MOSFET. Utilizing an onboard multiplier, the LT3799 typically achieves power factors of 0.97. The FAULT pin provides notification of open and short LED conditions.The LT3799 uses a micropower hysteretic start-up to efficiently operate at offline input voltages, with a third winding to provide power to the part. An internal LDO provides a well regulated supply for the part’s internal circuitry and gate driver. TRIAC Dimmable LED Current Regulation LT3799 YES ±10% LT3799-1 NO ±5% Applications Offline 4W to 100W+ LED Applications High DC VIN LED Applications

The ADP8140 provides high current control of up to four LED drivers. Each driver can sink up to 500 mA. The sink current is programmed for all four drivers with one external resistor.The device features a feedback output that controls an external power supply for optimal efficiency. The ADP8140 also protects the LEDs, power supply, and itself against thermal events, short circuits, overvoltages, and LED open circuits. Multiple ADP8140 ICs are easily connected in parallel to drive additional LED strings or higher current LEDs. The ADP8140 is available in a small, thermally enhanced, lead frame chip scale package (LFCSP).Applications High brightness LED lighting Large format LED backlighting