Demonstration circuit 2176A features the LT3909, a 2-string × 50mA, 2MHz step-up LED driver with ±1.8% current matching. The LT3909 precisely regulates two LED strings for equal current, supports LED dimming that reduces brightness down to a 1/40,000 ratio, protects against faults and also reports faults. The LT3909 consists of a step-up converter with a fixed 2MHz switching frequency and current sources for the LED strings. The maximum current in each LED string is 40mA. The ISET resistor can be changed to 20.0kΩ to program the string current to 50mA – see the data sheet for an application example with 50mA string current. Voltage feedback resistors optimize operation for LEDs that are 35V maximum.

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.

Demo circuit DC1274A features the LTM8040 36V, 1A step-down constant current μModule® LED driver. The demonstration circuit is designed to drive a single LED or string of LEDs at up to 1A from a wide input voltage range of 4V to 36V. The maximum LED string voltage is 13V and the minimum voltage varies depending upon the BIAS pin supply arrangement.

Demonstration circuit 850A is a Boost LED Driver featuring the LTC3783 a boost/SEPIC/flyback LED driver controller. The demo board requires a 3V to 14.4V input and provides 360mA LED current at up to 25V. It incorporates an output overvoltage protection feature to limit output voltage to less than 27V if the LED string is inadvertently disconnected. The LT3783 features 1000:1 PWM dimming for brightness control and analog dimming control.

Demonstration circuit 2686A is a 1.3A 8-switch matrix LED dimmer system with an I2C to CAN-physical transceiver featuring the LT3967 and LT3960. This demonstration circuit connects directly to a LED string and LED driver demonstration circuit to allow for independent dimming control of up to 8 channels of LEDs. A Linduino® One demonstration circuit is used to interface with the board and can connect in one of two different ways: Connect directly to a Linduino One demonstration circuit with a QuikEval™ ribbon cable. Connect using the LT3960 break-off board to connect to the I2C master device, but pass data over two twisted pair lines to the LT3960 on the main PCB. The LT3967 matrix dimmer features 8 individually con-trolled 1.3A rated floating NMOS switch channels and can support up to 56V of LEDs per device. The channels of the LT3967 can be configured for series connections, or non-series connections. Additional DC2686A demo circuits can be connected in series for higher number of LEDs, or in parallel to allow for higher current operation. Resistors are used to configure both the I2C slave address as well as the default start-up state. The default configuration for DC2686A sets the I2C address as 0000 with all LEDs off. See the LT3967 data sheet for details. The LT3960 I2C to CAN-Physical transceiver is used to send and receive I2C data through harsh or noisy environments at up to 400kb/s using the CAN-Physical layer for differential signaling over twisted pair connections. Both SDA and SCL data lines are converted to differential signals and are shared between devices connected to the bus. This allows for physical separation of the I2C source with the LT3960 transceiver board and the LT3967 main PCB along with the LED driver. This demo circuit is designed to be easily configured and interfaced with a compatible low output capacitance LED driver and LED string. It can easily be directly attached to a buck LED driver or a floating buck-mode LED driver. More sophisticated setups with series matrix dimmers for higher number of LEDs such as 12 or 16 is possible. Please consult factory applications for details or look for more details on analog.com. The LT3967 and LT3960 data sheets give complete description of the parts, their operation and applications information. The data sheets must be read in conjunction with the demo manual for demonstration circuit DC2686A. The LT3967EFE is assembled in a thermally enhanced 28-lead TSSOP package. The LT3960EMSE is assembled in a 10-lead MSOP package.

temperature range.APPLICATIONS Advanced TVs PDP HDTVs LCD TVs (HDTV ready) LCD/DLP? rear

DC1436A is a 16-Channel High Voltage Boost LED Driver featuring the LT3754. The LT3754 drives up to 50mA per string and has a maximum LED string voltage of 45V. The VIN terminal is powered from an 8V to 14V input supply and is distinct from the 24V PVIN supply (20V to 28V) for best thermal performance. Overvoltage protection is set at 55V in case the LEDs are removed from the circuit. If the LEDs are opened, the FAULT terminal output flag goes low and reports the fault condition. If one or more of the 16 LED channels is not used, its LED pin or terminal should be tied to VOUT (LED+) to disable it. Multiple channels can be tied in parallel by tying their LED1-LED16 pins together.

Demonstration Circuit 366A is a low noise constant frequency regulated charge pump featuring the 100mA output current LTC3200. The demo board accepts a 2.7V to 4.5V input voltage and drives six white LEDs in parallel, resulting in 16.6mA per LED. Ballast resistors are employed to provide more uniform light intensity fromr the paralleled LEDs.

Demonstration circuit 876 is a dual step-up white LED driver with wide dimming range featuring the LT3486. The board is optimized to drive a string of six, eight, or ten white LEDs at 100mA from each of its two outputs with a PVIN input voltage range of 3V to 25V. The maximum LED output voltage must be less than 36V as the overvoltage protection at the output will limit the maximum output voltage to 36V in the case of an open circuit load. The high input voltage range, high-efficiency low-side internal 1.3A NPN power switches, ground-referenced low-voltage current sense resistors, PWM pins for 1000:1 dimming ratio, control pins for brightness adjust, overvoltage protection, shutdown control pin, externally programmable switching frequency, low shutdown current and internal soft-start capacitor make the LT3486 an extremely powerful and versatile LED driving IC for portable applications and displays.

Demonstration circuit 2339A is a high current synchronous step-down LED driver featuring the LT3744. The unique drive stage used on the LT3744 allows the anodes of three LEDs to be connected together for better heat sinking in both the step-down configuration and the inverting buck-boost configuration (shown in a separate demonstration circuit DC1930A). The pros and cons of each configuration can be found in the data sheet.  The DC2339A targets high power LEDs and laser diodes (not included). The 3 LEDs are driven from the same output, but each LED is individually controlled. The input voltage range is 5.5V to 30V.