The LT3439 is a push-pull DC/DC transformer driver that reduces conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by controlling the output switch voltage and current slew rates. Slew rates are user adjustable to optimize output noise versus efficiency. The LT3439 can reduce high frequency harmonic content by as much as 40dB with only a minor decrease in efficiency. The LT3439 includes two 1A current limited power switches to ensure start-up under heavy loads. It also includes an oscillator that can be synchronized to an external clock for more accurate placement of switcher harmonics. Protection features include current limiting, undervoltage lockout, thermal shutdown and cross conduction prevention circuitry.