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

Laser Drivers

Demonstration circuit DC1666A is a synchronous four-switch buck-boost LED driver controller. It accepts an input voltage from 4.7V to 60V, and drives up to 25V of LEDs at 2A. DC1666A features both PWM and analog dimming of the LED string. It has an OPENLED flag that indicates when the LED string has been removed and it has a SHORTLED flag that indicates that the output has been shorted to GND. In both cases, the IC remains in control and well protected.

DISPLAY INTERFACE, 10BIT, 1.9V, LQFP-80; IC Interface Type:I2C; Interface Applications:LCD Monitors and Projectors, Plasma Display Panels, RGB Graphics Processing; Supply Voltage Min:1.7V; Supply Voltage Max:1.9V; No. of Pins:80Pins RoHS Compliant: Yes

IC Multidisplay LED Controller Features: Step-Up/Direct-Connect Fractional Charge Pump Provides Up to 92% Efficiency Up to 400mA Continuous Output Current Independent Current and Dimming Control for 1-6 LED MAIN, 1-4 LED SUB and RGB LED Displays LED Currents Programmable Using 2-Wire I2C™ Serial Interface 1% LED Current Matching Low Noise Constant Frequency Operation* Minimal Component Count Automatic Soft-Start Limits Inrush Current 16 Exponentially Spaced Dimming States Provides 128:1 Brightness Range for MAIN and SUB Displays Up to 4096 Color Combinations for RGB Display Low Operating Current: IVIN = 180µA Tiny, Low Profile 24-Lead (4mm × 4mm × 0.75mm) QFN Package

3A, DC/DC Converter with Dual Rail-to-Rail Current Sense Features: Dual 100mV Rail-to-Rail Current Sense Amplifiers Wide Input Voltage Range: 2.5V to 25V 3A, 42V Internal Switch High Efficiency Power Conversion: Up to 93% Drives LEDs in Boost, Buck-Boost or Buck Mode Frequency Set by External Resistor: 200kHz to 3.5MHz Programmable Soft-Start Low VCESAT Switch: 0.3V at 2.5A Capable of Positive and Negative Output Voltages (Boost, Inverting, SEPIC, Flyback) Available in Thermally Enhanced 20-Lead (4mm × 4mm) QFN and 20-Lead TSSOP Packages

36V, 2A Synchronous Step-Up LED Driver Features:±2.5% LED Current Regulation±2% Output Voltage Regulation5000:1 PWM Dimming at 100Hz128:1 Internal PWM DimmingSpread-Spectrum Frequency ModulationSilent Switcher® Architecture for Low EMIOperates in Boost, Buck Mode and Buck-Boost Mode2.8V to 36V Input Voltage RangeUp to 34V LED String Voltage2A, 40V Internal Switches200kHz to 2MHz with SYNC FunctionAnalog or Duty Cycle LED Current ControlOpen/Short LED Protection and Fault IndicationThermally Enhanced 28-Pin (4mm × 5mm) QFN

Demonstration circuit 976 is a Quadruple High Power LED Driver in Buck Mode featuring the LT3476EUHF. The LT3476 is a quad output, multitopology DC/DC converter designed to operate as a current source for driving high current LEDs. Each of the four regulators on the demo circuit is independently operated. The VIN power supply for the IC ranges from 2.8V to 16V. The PVIN power supply for the buck regulators ranges up to 33V. On the demo circuit, the default current for each output channel is 350mA but it can be adjusted up to 1.05A via resistor dividers at the VADJ pins. The output current should not exceed the rated current of the LEDs used. If 1W LEDs, such as the Lumileds Luxeon LEDs, are used, 350mA current is the maximum. 1A output current is reserved for 3W LEDs, such as Luxeon III. The input voltage is limited by the CAP pin overvoltage protection threshold. As a result, each channel of the demo circuit can drive up to 27V total LED voltage.

The LTC3202 is a low noise, constant frequency charge pump DC/DC converter that uses fractional conversion to increase efficiency in white LED applications. The part can be used to produce a regulated voltage or current of up to 125mA from a 2.7V to 4.5V input. Low external parts count (two flying capacitors and two small bypass capacitors at VIN and VOUT) make the LTC3202 ideally suited for small, battery-powered applications.An internal 2-bit DAC allows LED current to be adjusted for LED brightness control. The LTC3202 also has thermal shutdown protection and can survive a continuous short-circuit from VOUT to GND. Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. A low current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1?A.The LTC3202 is available in the 10-pin MSOP and 3mm x 3mm DFN packages.Applications White LED Backlighting Programmable Boost Current Source?

DC507A: Demo Board for the LT1937 White LED Step-Up Converter in SC70 and ThinSOT.