The LT 1534/LT1534-1 are a new class of switching regulator designed to reduce conducted and radiated electromagnetic interference (EMI). Ultralow noise and EMI are achieved by providing user control of the output switch slew rates. Voltage and current slew rates can be independently programmed to optimize switcher harmonic content versus efficiency. The LT1534/LT1534-1 can reduce high frequency harmonic power by as much as 40dB with only minor losses in efficiency.