DC1772A

DC1772A demonstration circuit is a high-voltage LED controller with internal PWM dimming. It generates its own PWMOUT waveform for accurate PWM dimming with up to 25:1 brightness ratio. It accepts an input voltage from 8 to 60V (8V UVLO and 9.1V rising turn-on), and drives up to 60V of LEDs at 1A (when PVIN is less than VLED). DC1772A features both PWM and analogue dimming of LED string. It has an (active low) OPENLED flag that indicates when the LED string has been removed. DC1772A features high efficiency at 350KHz switching frequency. At high LED string voltages up to 60V and 1A of LED current, the single switch controller has 94% efficiency. The open LED overvoltage protection uses IC’s constant voltage regulation loop to regulate the output to approximately 69.8V if the LED string is opened although it may reach 74V peak during transient from running LEDs to open. The maximum LED string voltage can be raised from 60V to 65V (or higher) with a simple change of feedback resistors.

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