The LT3754 offers ±2.8% (±0.7% typical) LED current matching to ensure uniform brightness of the display. Dimming ratios as high as 3,000:1 can be attained by using True Color PWM™ dimming. A programmable 100kHz to 1MHz fixed frequency operation and current mode architecture offers stable operation over a wide range of supply and output voltages while minimizing the size of the external components. Additionally, the switching frequency is synchronizable to an external clock. Its thermally enhanced 5mm x 5mm QFN-32 package offers a very compact solution footprint for LED backlighting applications.
The LT3754 uses an external N-Channel MOSFET switch to provide a boost mode constant current source. However, even when VIN exceeds VOUT, the LT3754 will continue to accurately regulate the LED current. The internal boost controller uses an adaptive feedback loop to regulate the output voltage slightly higher than the required LED voltage to ensure maximum efficiency. If any of the LED strings experiences an open circuit, it will continue to regulate the existing strings and signals the OPENLED alert pin. If higher current LEDs are required, multiple strings can be combined, enabling the LT3754 to drive up to eight strings of ten 100mA LEDs or four channels of ten 200mA LEDs. Additional features include programmable overvoltage protection, LED current derating based on junction temperature and/or LED temperature and output voltage limiting when all LED strings are disconnected.
