By Analog Devices Inc 54
Linear Technology/Analog Devices' LT3922 is a 36 V, 2 A synchronous, step-up DC/DC converter that utilizes fixed-frequency, peak current control and provides PWM dimming for a string of LEDs. The LED current is programmed by an analog voltage or the duty cycle of pulses at the CTRL pin. This LED driver will maintain ±2% current regulation through an external sense resistor over a wide range of output voltages. The switching frequency is programmable from 200 kHz to 2 MHz by an external resistor at the RT pin or by an external clock applied at the SYNC/SPRD pin. With the optional spread spectrum frequency modulation enabled, the frequency varies from 100% to 125% to reduce EMI. The LT3922 also includes a driver for an external high side PMOS for PWM dimming and an internal PWM signal generator for analog control of PWM dimming when an external signal is not available. Additional features include an accurate external reference voltage for use with the CTRL and PWM pins, an LED current monitor, an accurate EN/UVLO pin threshold, open-drain fault reporting for open-circuit and short-circuit load conditions, and thermal shutdown. This LED driver comes in a 28-pin QFN package that has a temperature range of -40°C to +125°C (TJ). The LT3922 is perfect for machine vision, automotive and industrial lighting applications.
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