DC1319B-B: 500mA @ 80V Max, 8 ~ 80V in

Demonstration circuit 1319B-A/1319B-B is a high voltage and high current LED driver controller. The VIN pin input voltage is as high as 100V, and the LED output voltage is also as high as 100V. The demonstration circuit is assembled as a boost topology from 8V to 80V input and up to 80V LED output at 0.5A with an open-LED status pin (DC1319B-A) or a sync input pin (DC1319B-B). DC1319B features PWM dimming, analog dimming, shutdown, and open-LED overvoltage protection. Efficiency at 12VIN is as high as 91% for 40W output.

The switching frequency is set at 300 kHz to accommodate the automotive switching frequency range. Small ceramic input and output capacitors are used to save space and cost and a high voltage 100V external power switch and a 100V catch diode are used for up to 40W (80V at 0.5A) output as assembled. The open-LED overvoltage protection limits the output to approximately 92V if the LED string is opened.

Note: LED output voltages above 80V, but less than the open-LED voltage of 92V, are possible with limitations to low input voltage operation. Please consult the factory.

For low input voltage operation, the CTRL pin voltage is reduced as the input voltage drops below 10V, reducing LED brightness and restraining the peak switch currents in order to limit inductor and switch size. UVLO turns the LEDs off when VIN drops below 8V.

DC1319B PWM dimming is simple. The boost topology LED string returns to the LED terminal and the PWM dimming MOSFET turns the LED string on and off with an input to the PWM dimming terminal. For the highest PWM dimming ratio, it is recommended to use 100Hz as a PWM dimming frequency. Information regarding PWM dimming ratios and performance can be found in the LT3756-2/LT3756-1 data sheet in the Applications Information section.

Soft-start is provided with a simple and small capacitor to maintain control of the switch current during turn on for high power designs.

Modifications can be made to the DC1319B in order to convert the board from a boost topology LED driver to any other topology. Please consult the factory or LT3756-2/LT3756-1 data sheet for details regarding how to customize the DC1319B or how to design different topologies for custom specifications.