LT3755-2 Datasheet

• 3000:1 True Color PWM^™ Dimming
• Wide Input Voltage Range: 4.5V to 40V
• Output Voltage Up to 75V
• Constant-Current and Constant-Voltage Regulation
• 100mV High Side Current Sense
• Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topology
• Adjustable Frequency: 100kHz to 1MHz
• Open LED Protection
• Programmable Undervoltage Lockout with Hysteresis
• Improved Open LED Status Pin (LT3755-2)
• PWM Disconnect Switch Driver
• CTRL Pin Provides Analog Dimming
• Low Shutdown Current: <1µA
• Programmable Soft-Start
• Thermally Enhanced 16-Lead QFN (3mm × 3mm) and MSOP Packages
• AEC-Q100 Qualified For Automotive Applications

• High Power LED
• Battery Chargers
• Accurate Current Limited Voltage Regulators

The 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 LT3755-2 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.