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

The LTC3207/LTC3207-1 are highly integrated multi-display LED drivers. The device contains a high-efficiency, low-noise charge pump to provide power to 12 universal LED current sources and one camera LED current source. The LTC3207/LTC3207-1 require only five small ceramic capacitors to form a complete LED power supply and current controller. In addition there are two I2C addresses available.The display currents are set by an internal precision current reference. Independent dimming, On/Off, blinking and gradation control for all universal current sources is achieved via the I2C serial interface. 6-bit linear DACs are available for adjusting brightness levels for each universal LED current source. The CAM current source has a 4-bit linear DAC to adjust brightness.The LTC3207/LTC3207-1 charge pumps optimize efficiency based on the voltage across the LED current sources. The device powers-up in 1x mode and will automatically switch to boost mode whenever any enabled LED current source begins to enter dropout. The first dropout switches the IC into 1.5x mode and a subsequent dropout switches the LTC3207/LTC3207-1 into 2x mode. The device resets to 1x mode whenever a data register is updated via the ?I2C?port.Applications Video Phones with QVGA+ Displays

DC1205A: Demo Board for LT3592 500mA Wide Input Voltage Range Step-Down LED Driver with 10:1 Dimming.

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

DC484A: Demo Board for the LT1937 White LED Step-Up Converter in SC70 and ThinSOT.

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

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”.

60V Synchronous Boost LED Controller Features: 3000:1 External PWM Dimming 250:1 Internal PWM Dimming Wide VIN Operating Range: 2.5V to 38.5V Synchronous Boost Output Voltage up to 60V Spread-Spectrum Frequency Modulation for Lower EMI PMOS Switch Driver for PWM and Output Disconnect Constant Current (±3.5%) Regulation Constant Voltage (±2%) Regulation Rail-to-Rail LED Current Sense: 0V to 60V Programmable VIN Undervoltage Lockout Analog Dimming via Two Control Pins 100kHz to 1MHz Operation Programmable Open LED Protection with OPENLED Flag Short-Circuit Protection and SHORTLED Flag Drives LEDs in Boost, SEPIC, Buck Mode, or BuckBoost Mode Configurations 28 Lead TSSOP and QFN (4mm × 5mm) Exposed Pad Packages

The LT3799-1 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 LT3799-1 typically achieves power factors of 0.97. The FAULT pin provides notification of open and short LED conditions. The LT3799-1 offers improved line regulation over the LT3799, but is not designed for use with a TRIAC dimmer.The LT3799-1 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 Regulator LT3799 Yes ± 10% LT3799-1 No ± 5% Applications Offline 4W to 100W+ LED Applications High DC VIN LED Applications

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