Analog Devices' LT8376 60 V, 3 A synchronous step-down LED drive utilizes Silent Switcher technology to achieve very low EMI

     ADI's LT8376 monolithic synchronous step-down DC/DC converter uses fixed frequency peak current control to provide PWM dimming for a string of LEDs. The analog voltage or pulse duty cycle on the CTRL pin is programmed against the LED current. The resistance divider of FB pin can set the output voltage limit.

     The LT8376 also includes a driver, an external high voltage side PMOS for PWM dimming, and an internal PWM signal generator for PWM dimming analog control when there is no external signal. The external resistor on the RT pin or the external clock on the SYNC/SPRD pin programs the switching frequency between 200 kHz and 2 MHz. The frequency is changed from 100% to 125% to reduce EMI with optional spread spectrum frequency modulation enabled.

     Additional functions include LED current monitors, accurate EN/UVLO pin thresholds, open and leakage fault reporting for open and short circuit load conditions, and thermal shutdown. The LT8376 utilizes proprietary Silent Switcher technology to achieve very low EMI.

     The evaluation board EVAL-LT8376-AZ is a 60V, 2A synchronous step-down LED driver with LT8376. When the VIN is between 43 V and 57 V, EVAL-LT8376-AZ drives up to 36 V single string LED at 1.5 A. The board has an undervoltage lockout (UVLO) set to 40 V and a 2 V hysteresis open. It operates at a switching frequency of 350 kHz and has an optional Spread Spectrum Modulation (SSFM) that adjusts the switching frequency from fSW to fSW+25% to reduce EMI emissions when enabled.