Two Channel Boost Regulator with DHC for LED Backlighting Evaluation Board

Synchronous Buck Controllers for Precision Dimming LED Drive Evaluation Module Board

Evaluation Module - TPS92661Q LED Lighting Matrix Manager for Exterior Automotive Lighting

Demonstration circuit 976 is a Quadruple High Power LED Driver in Buck Mode featuring the LT3476EUHF. The LT3476 is a quad output, multitopology DC/DC converter designed to operate as a current source for driving high current LEDs. Each of the four regulators on the demo circuit is independently operated. The VIN power supply for the IC ranges from 2.8V to 16V. The PVIN power supply for the buck regulators ranges up to 33V. On the demo circuit, the default current for each output channel is 350mA but it can be adjusted up to 1.05A via resistor dividers at the VADJ pins. The output current should not exceed the rated current of the LEDs used. If 1W LEDs, such as the Lumileds Luxeon LEDs, are used, 350mA current is the maximum. 1A output current is reserved for 3W LEDs, such as Luxeon III. The input voltage is limited by the CAP pin overvoltage protection threshold. As a result, each channel of the demo circuit can drive up to 27V total LED voltage.

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.

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 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 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