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.

Demonstration circuit DC2857A is a 36V 2A synchronous 2MHz boost LED driver featuring the LT3922-1. It drives a single string of LEDs at 330mA up to 34V when VIN is between 7V and 28V. It runs down to 4VIN with reduced ILED and can withstand VIN as high as 36V, but has overvoltage lockout (OVLO) set for 28V for this application. DC2857A runs at 2MHz switching frequency. Spread spectrum frequency modulation (SSFM) can be turned on with a simple jumper, reducing EMI. DC2857A comes with low EMI features including optimized layout, SSFM and input EMI filter. It passes CISPR 25 class 5 conducted and radiated EMI. It is protected against both open and short LED conditions and reports the faults. The LT3922-1 has an input voltage range from 2.8V to 36V. Its internal synchronous 2A 40V switches allow up to 34V of LEDs on the output with room for over voltage protection and overshoot during an open LED event. It has adjustable switching frequency between 200kHz and 2.5MHz. It can be synchronized to an external source or programmed with SSFM for low EMI. The PWMTG highside PWM MOSFET driver assists with short-circuit protection and versatility. LT3922-1 can be configured as a boost, boost-buck, or buck mode LED driver and maintain all of its low EMI, PWM dimming, and fault diagnostic features. The LT3922-1 can be PWM dimmed with an external PWM signal or an internally-generated PWM signal. DC2857A has a jumper that can be set to switch between internallygenerated PWM signal, externally-generated PWM signal, and no PWM signal (100% on). It can be analog dimmed with a control voltage on its control pin (CTRL). When run with both PWM dimming and spread spectrum, the spread spectrum aligns itself with the PWM signal for flicker-free operation. Small ceramic input and output capacitors are used to save space and cost. The board is designed with tiny, high frequency capacitors on both sides of the VOUT pins for a reduction in radiated EMI. The open LED overvoltage protection uses the IC’s constant voltage regulation loop to regulate the output to approximately 37.5V if the LED string is opened, although it may reach almost 40V peak during transient from running LEDs to open. There is a protection diode from LED+ to GND to prevent negative ringing during a short-circuit. The output current can be monitored through the ISMON output pin. Undervoltage and overvoltage lockout can be adjusted on the circuit with a few simple resistor choices. There is an EMI filter on the input of DC2857A. Please follow the recommend layout and four-layer thickness of DC2857A for low EMI applications. The LT3922-1 data sheet gives a complete description of the part, operation and applications information. The LT3922EUFD-1 is assembled in a 28-lead plastic 4mm × 5mm QFN package with a thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance. See the data sheet section Layout Considerations.

3.3 V Dual-Loop 50 Mbps to 3.3 Gbps Laser Diode Driver

4-Channel, LVDS, Dual-Output, Laser Diode Driver with Oscillator Features: Dual, current-controlled output current sources with 4 input channels TTL-selectable output Stable on-chip oscillators with independent frequency and amplitude control TTL- or LVDS-selectable write channel enables negative logic Independent TTL oscillator enables positive logic 170 mA minimum output current for the read channel 510 mA minimum output current for Write Channel 1 330 mA minimum output current for Write Channel 2 165 mA minimum output current for Write Channel 3 950 mA typical total output current Typical rise time/fall time of  0.8 ns Low power consumption Single 5 V power supply (±10%)

600mA Main/Camera LED Controller Features: Multimode Charge Pump Provides Up to 94% Efficiency (1x, 1.5x, 2x) Up to 600mA Total Output Current LTC3209-1: 8 Current Sources Available as 6 × 25mA MAIN, 1 × 400mA CAM and 1 × 15mA AUX LTC3209-2: 8 Current Sources Available as 5 × 25mA MAIN, 2 × 200mA CAM and 1 × 15mA AUX LED On/Off and Brightness Level Programmable Using 2-Wire I2C™ Interface Automatic Charge Pump Mode Switching or Fixed Mode for Power Supply Generation Low Noise Constant Frequency Operation Internal Soft-Start Limits Inrush Current During Start-up and Mode Switching Short Circuit/Thermal/Open-Shorted LED Protection 256 Brightness States for MAIN Display 16 Brightness States for CAM Display 4 Brightness States for AUX Display 20-Lead (4mm × 4mm) QFN 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

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