The LT3756 and LT3756-1 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 7V 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 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. Both parts are available in the 16-lead QFN (3mm x 3mm) and MSOP packages.
- 3000:1 True Color PWM™ Dimming
- Output Voltage Up to 100V
- Wide Input Voltage Range: 6V to 100V
- 100mV High Side Current Sense
- Adjustable Frequency: 100kHz to 1MHz
- Programmable Undervoltage Lockout
- Frequency Synchronization (LT3756-1)
- CTRL Pin Provides Analog Dimming
- Programmable Soft-Start
- Constant-Current and Constant-Voltage Regulation
- Drives LEDs in Boost, Buck Mode,
Buck-Boost Mode, SEPIC or Flyback Topology
- Open LED Protection
- Open LED Status Pin (LT3756)
- PWM Disconnect Switch Driver
- Low Shutdown Current: <1µA
- Thermally Enhanced 16-Lead QFN
(3mm × 3mm) and MSOP Packages
- High Power LED Applications