Demonstration circuit 1137 is a 20mA Six White LED Driver and OLED driver with Integrated Schottky featuring the LT3498. The LT3498 is a dual output boost converter featuring a 2.3MHz PWM LED driver and a PFM (Pulse Frequency Modulation) OLED driver. The demo board is designed to operate from 3V to 5V, ideal for Li Ion battery powered dual display applications, such as main and sub-displays for cell phones. The demo board offers flexible LED dimming methods. Users can use DC dimming, filtered PWM dimming or direct PWM dimming. The parts functions as a “one-wire” current source from the LED string point of view. The circuit protection clamps LED driver output to 27V (typ) if an open circuit condition occurs. When CTRL2 is higher than 1.5V, the demo board OLED supply output voltage is 16V. It can deliver up to 24mA from a 3V source.

Demonstration circuit 1288 is a Triple Boost or Buck-Boost LED Driver featuring the LT3496EUFD (for evaluating an LT3496 buck mode LED driver, use the demonstration circuit 986). The LT3496 is a triple output DC/DC converter designed to operate as current sources for driving high current LEDs. The board can be configured as either a buck-boost (default) or boost solution. The current for each output is set at 200mA in either mode. The three LEDs are included in the demo board assembly. The operating power input voltage (PVIN) range is 8V to 16V. The buck-boost circuit can tolerate an input voltage up to 40V when the LED string is on the high side. The part shuts down when the overvoltage threshold is reached. For a typical application with 5 LEDs totaling 16V of LED voltage, the circuit will operate until PVIN reaches 22V if the overvoltage protection is set to 38V.

4.5A Monolithic LED Drivers with True Color PWM Dimming Features: True Color PWM™ Dimming Delivers Constant LED Color with Up to 3000:1 Range Wide Input Voltage Range: 2.8V to 36V 4.5A, 60mΩ, 42V Internal Switch Drives LEDs in Boost, Buck-Boost or Buck Modes Integrated Resistors for Inductor and LED Current Sensing Program LED Current: 100mA to 1050mA (LT3478-1) (10mV to 105mV)/RSENSE (LT3478) Program LED Current De-Rating vs Temperature Separate Inductor Supply Input Inrush Current Protection Programmable Soft-Start Fixed Frequency Operation from 200kHz to 2.25MHz Open LED Protection (Programmable OVP) Accurate Shutdown/UVLO Threshold with Programmable Hysteresis 16-Pin Thermally Enhanced TSSOP Package

LIGHTING DEVELOPMENT KITS;

LT3466 is a dual full function step-up DC/DC converter specifically designed to drive up to 20 White LEDs (10 in series per converter) with a constant current. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors and expensive factory calibration.The two independent converters are capable of driving asymmetric LED strings. The dimming of the two LED strings can also be controlled independently. The LT3466 is ideal for providing backlight for main and sub-displays in cell phones and other handheld devices.The LT3466 operating frequency can be set with an external resistor over a 200kHz to 2MHz range. A low 200mV feedback voltage minimizes power loss in the current setting resistor for better efficiency. Additional features include output voltage limiting when LEDs are disconnected and internal soft-start.The LT3466 is available in the 10-pin (3mm × 3mm × 0.75mm) DFN and 16-pin thermally enhanced TSSOP packages.Applications Main/Sub Displays Digital Cameras, Sub-Notebook PCs PDAs, Handheld Computers Automotive

EVAL KIT, CONSTANT CURRENT, LED DRIVER;

The ADM8845 uses charge pump technology to provide thepower required to drive up to six LEDs. The LEDs are used forbacklighting a color LCD display, having regulated constant current for uniform brightness intensity. The main display canhave up to four LEDs, and the sub display can have one or two LEDs. The digital CTRL1 and CTRL2 input control pins controlthe shutdown operation and the brightness of the main and subdisplays.To maximize power efficiency, the charge pump can operate ina 1?, 1.5?, or 2? mode. The charge pump automaticallyswitches between 1?/1.5?/2? modes, based on the input voltage,to maintain sufficient drive for the LED anodes at the highestpower efficiency. Improved brightness matching of the LEDs is achieved by afeedback pin to sense individual LED current with a maximum matching accuracy of 1%.Applications Cellular phones with main and sub displays White LED backlighting Camera flash/strobes and movie lights Micro TFT color displays DSC PDAs

Evaluation board EVAL-LT8356-1-AZ is a high voltage LED controller featuring the LT8356-1. It is assembled as a buck-boost mode LED driver but can be altered to a boost LED driver by adjusting the FB network and LED-connection. EVAL-LT8356-1-AZ drives a single string of LEDs up to 36V at 1A when the input is between 8V and 36V. It has an undervoltage lockout (UVLO) set at 6.5V falling and 7.5V rising. The evaluation board features PWM dimming, analog dimming, shutdown, open LED and short LED fault protection and reporting. EVAL-LT8356-1-AZ runs at 250kHz switching frequency and features spread spectrum frequency modulation (SSFM) modulating its switching frequency from 250kHz to 310kHz to reduce EMI emissions. Small ceramic input and output capacitors are used to save space and cost. A high voltage 100V external power switch and 100V catch diode are used for up to 36W buck-boost mode output as assembled. The open LED overvoltage protection (OVP) uses the IC’s constant voltage regulation loop to limit the LED+ to LED– voltage to approximately 41V if the LED string is opened. The VOUT, if referenced to GND, will jump to VIN + 41V if the LED string is opened. The input and output filters on EVAL-LT8356-1-AZ help further reduce its EMI. These filters consist of a small ferrite bead or inductor and high frequency ceramic capacitors. A small resistor on the gate pin of the power MOSFET is used to reduce high frequency EMI. These filters, combined with proper board layout and SSFM, are very effective in reducing EMI to comply with CISPR25 class 5 limits. Please follow the recommended layout and the four-layer PCB thickness of EVAL-LT8356-1-AZ. For best efficiency and PWM dimming performance, the EMI filters can be removed. The LT8356-1’s integrated PWMTG high-side PMOS driver assists with PWM dimming of the connected LEDs. The LED string can be PWM-dimmed for accurate brightness control with an externally generated PWM signal for highest achievable dimming ratio. It can also utilize LT8356-1’s internally generated PWM feature for up to 128:1 exponential dimming. When running PWM dimming, the SSFM aligns itself with the PWM signal for flicker-free operation of the LED string. This applies to both internal and external PWM dimming. The LT8356-1 uses CTRL and IADJ pins for two-pin analog dimming. The input undervoltage lockout (UVLO), LED current, output overvoltage protection (OVP), and switching frequency, can all be easy adjusted with simple resistor changes to EVAL-LT8356-1-AZ. Modifications can be made to convert the board from buck-boost mode LED driver to boost and buck mode LED Driver, and maintain low EMI, PWM dimming and fault diagnostic features. Buck mode and boost LED Driver schematics are provided in the data sheet. Please consult the data sheet or the applications team regarding how to customize EVAL-LT8356-1-AZ. The LT8356-1 data sheet gives a complete description of the part, operation, and applications information. The data sheet must be read in conjunction with the demo manual for evaluation board EVAL-LT8356-1-AZ. The LT8356IUDCM-1 is assembled in a 20-lead side solderable plastic QFN package with a thermally enhanced exposed ground pad. Proper board layout is essential for maximum performance. See the data sheet section “Designing the Printed Circuit Board”.

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 LT3954 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator. It features an internal low side N-channel MOSFET rated for 40V/5A. The LT3954 is ideally suited for driving high current LEDs, but also has features to make it suitable for charging batteries and supercapacitors. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A voltage feedback pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.The LT3954 senses output current at the high side or at the low side of the load. The internal PWM generator can be configured to self-oscillate at fixed frequency with duty ratio programmable from 4% to 96%. When driven by an external signal, the PWM input provides LED dimming ratios of up to 3000:1. The CTRL input provides additional analog dimming capability.Applications High Power LEDs Output Short-Circuit Protected Boost Battery and SuperCap Chargers Accurate Current Limited Voltage Regulators