The MC34067/MC33067 are high performance zero voltage switch resonant mode controllers designed for off- line and dc- to- dc converter applications that utilize frequency modulated constant off-time or constant deadtime control. These integrated circuits feature a variable frequency oscillator, a precise retriggerable one-shot timer, temperature compensated reference, high gain wide bandwidth error amplifier, steering flip-flop, 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 soft- start circuitry, input undervoltage lockout with selectable thresholds, and reference undervoltage lockout. These devices are available in dual-in-line and surface mount packages. Features •Zero Voltage Switch Resonant Mode Operation •Variable Frequency Oscillator with a Control Range Exceeding 1000:1 •Precision One-Shot Timer for Controlled Off-T ime •Internally Trimmed Bandgap Reference •4.0 MHz Error Amplifier •Dual High Current Totem Pole Outputs •Selectable Undervoltage Lockout Thresholds with Hysteresis •Enable Input •Programmable Soft-Start Circuitry •Low Startup Current for Off-Line Operation •Pb-Free Packages are Available*
