The MC34066/MC33066 are high performance resonant mode controllers designed for offline and dctodc converter applications that utilize frequency modulated constant ontime or constant offtime control. These integrated circuits feature a variable frequency oscillator with programmable deadtime, precision retriggerable oneshot timer, temperature compensated reference, high gain widebandwidth error amplifier with a precision output clamp, steering flipflop, and dual high current totem pole outputs ideally suited for driving power MOSFETs. Also included are protective features consisting of a high speed fault comparator and latch, programmable softstart circuitry, input undervoltage lockout with selectable thresholds, and reference undervoltage lockout. These devices are available in dualinline and surface mount packages. Variable Frequency Oscillator with a Control Range Exceeding 1000:1