The MC33033 is a high performance second generation, limited feature, monolithic brushless dc motor controller which has evolved from ON Semiconductor’s full featured MC33034 and MC33035 controllers. It contains all of the active functions required for the implementation of open loop, three or four phase motor control. The device consists of a rotor position decoder for proper commutation sequencing, temperature compensated reference capable of supplying sensor power, frequency programmable sawtooth oscillator, fully accessible error amplifier, pulse width modulator comparator, three open collector top drivers, and three high current totem pole bottom drivers ideally suited for driving power MOSFETs. Unlike its predecessors, it does not feature separate drive circuit supply and ground pins, brake input, or fault output signal. Included in the MC33033 are protective features consisting of undervoltage lockout, cycle−by−cycle current limiting with a selectable time delayed latched shutdown mode, and internal thermal shutdown. Typical motor control functions include open loop speed, forward or reverse direction, and run enable. The MC33033 is designed to operate brushless motors with electrical sensor phasings of 60°/300° or 120°/240°, and can also efficiently control brush dc motors.