Analog Devices Inc./Maxim Integrated

The LT3755, LT3755-1 and LT3755-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB 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 LT3755/LT3755-1/LT3755-2 sense output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability.ApplicationsHigh Power LEDBattery ChargersAccurate Current Limited Voltage Regulators

The LT3756, LT3756-1 and LT3756-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB 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 LT3756/LT3756-1/LT3756-2 sense output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability.ApplicationsHigh Power LED ApplicationsCurrent Limited Constant Voltage ApplicationsBattery Charging

The LT3759 is a wide input range, current mode, DC/DC controller which is capable of regulating either positive or negative output voltages from a single feedback pin. It can be configured as a boost, SEPIC or inverting converter.The LT3759 drives a low side external N-channel power MOSFET. An internal LDO regulator draws power from VINor DRIVE to provide up to a 4.75V supply for the gate driver. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. The operating frequency of LT3759 can be set over a 100kHz to 1MHz range with an external resistor, or can be synchronized to an external clock using the SYNC pin.The LT3759 features soft-start and frequency foldback functions to limit inductor current during start-up and output short-circuit. A window comparator on the FBX pin reports via thePGOODpin, providing output voltage status indication. The device is available in a 12-Lead exposed pad MSOP package.ApplicationsDatacom and Industrial Boost, SEPIC and Inverting ConvertersDistributed Power SuppliesPortable Electronic EquipmentAutomotive

The LT3761A is a DC/DC controller designed to operate as a constant-current source and constant-voltage regulator. It features a programmable internal PWM dimming signal. The LT3761A 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 LT3761A senses output current at the high side or at the low side of the load. The PWM input can be configured to self-oscillate at fixed frequency with duty ratio programmable from 4% to 96%. The LT3761A offers improved accuracy of internal PWM dimming over LT3761. 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.NOTESLT3761AHigher PWM Dimming Accuracy at Lower LED Current LevelsLT3761-1Frequency SynchronizationLT3761Open LED Status PinAPPLICATIONSHigh Voltage LED Strings >100V with Ground Referred Current SenseGrounded Anode LEDsBattery and SuperCap ChargersAccurate Current Limited Voltage Regulators