Demonstration circuit DC2342A is a 60V synchronous boost LED controller featuring the LT®3762. It drives a single string of LEDs at 2A up to 32V when VIN is between 7V and 28V. It runs down to 4VIN with reduced ILED and can withstand VIN transients as high as 30V. DC2342A runs at approximately 300kHz switching frequency. Spread spectrum frequency modulation (SSFM) can be turned on with a simple jumper, reducing EMI. DC2342A is designed for high power step-up LED controller applications that require excellent efficiency across the VIN range. This demonstration circuit is protected against both open and short LED conditions, each having its own flag. The LT3762 has an input range from 2.5V to 42V. It has an adjustable switching frequency between 100kHz and 1MHz. Enabling SSFM spreads the switching frequency from fSW down to fSW – 30% for reduced EMI. SSFM speed is set by placing a capacitor from the SSFM pin of the LT3762 to ground, and can be disabled by shorting this pin to GND. DC2342A has a simple jumper option to enable/disable spread spectrum frequency modulation. The LT3762 can be PWM dimmed with an external PWM signal, as well as an internally generated PWM signal. A capacitor from PWM to GND of the LT3762 sets the PWM frequency, while the PWM duty cycle is determined by the voltage on the DIM terminal. Between 0V and 3V, VDIM gives between 0.4% and 97% PWM duty cycle. DC2342A has a jumper that can be set to switch between internally generated PWM signal, externally generated PWM signal, and no PWM signal (100% on). When run with both PWM dimming and spread spectrum enabled, the spread spectrum aligns itself with the PWM signal for flicker free operation. DC2342A can also be analog dimmed by placing a voltage source at either of its two CTRL turrets. Small ceramic input and output capacitors are used to save space and cost. The open LED overvoltage protection uses the IC’s constant voltage regulation loop to regulate the output to approximately 35.5V if the LED string is opened, although it may reach almost 40V peak during the transient caused by an open circuit. There is a protection diode from LED+ to GND to prevent negative ringing during a short-circuit. Undervoltage lockout can be adjusted on the circuit with a few simple resistor choices. Further modifications can be made to DC2342A to reconfigure the circuit from a boost topology to operate as a buck-mode or buck-boost mode LED driver. Please consult the factory for details. The LT3762 data sheet gives a complete description of the part, operation and applications information. The data sheet must be read in conjunction with this Demo Manual for demonstration circuit DC2342A. The LT3762EUFD 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.

The LT3952A is a current mode step-up DC/DC converter with an internal, 60V, 80m? DMOS power switch. The LT3952A is specifically designed to drive high power LEDs in multiple configurations. It combines input and output current regulation loops with output voltage regulation to operate as a flexible current/voltage source.Programmable switching frequency with optional spread-spectrum modulation provides EMI reduction, while still allowing optimization of the external components for efficiency or component size. The LED current is programmable with an external sense resistor, and can be adjusted from zero to full scale with a voltage at the CTRL pin. The external PWM input provides LED ON/OFF control and 4000:1 dimming ratio, and an internal PWM generator delivers the efficiency of PWM dimming to standalone or I/O limited applications. The LT3952A is available in the thermally enhanced 28-lead TSSOP package.Applications Display Backlighting Automotive and Avionic Lighting Accurate Current-Limited Voltage Regulators

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

LED Lighting Drivers 1.0A LED Flash Driver

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

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.

Demonstration circuit 2020A is a 60VIN, 80VOUT LED driver. It generates its own PWMOUT waveform from its internal PWM generator for accurate PWM dimming with up to 33:1 brightness ratio. It accepts an input voltage from 5V to 60V and drives up to 67V of LEDs at 300mA (when PVIN is less than VLED). DC2020A features both PWM and analog dimming of the LED string. It has an OPENLED flag that indicates when the LED string has been removed. DC2020A features high efficiency at 350kHz switching frequency. At high LED string voltages up to 67V and 300mA of LED current, the single switch controller has 92% efficiency. The LT3955 has an internal 80V, 3.5A switch that simplifies the schematic and layout.

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

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