The LM3431 is a combination switching boost voltage regulator and multi-channel LED current controller.
The LM3431 evaluation board is designed to drive 4 parallel strings of 8 series LEDs at 140mA per string from an input voltage range of 8V to 18V. The boost switcher regulates LED cathode voltage for optimum efficiency, while allowing the output voltage to vary according to the LED forward voltage. The LM3431 incorporates complete fault protection features including LED short and open protection, over-current protection, over-voltage and under-voltage protection, and thermal shutdown. The error detection flag can be monitored at the DLY post, which has a programmable delay time.
The board includes a DIM input terminal for a selectable digital or analog dimming control signal. PWM dimming frequencies up to 1kHz at 100:1 contrast ratio and contrast ratios up to 500:1 at 200Hz are possible.