UC2633

The UC1633 family of integrated circuits was designed for use in phase locked frequency control loops. While optimized for precision speed control of DC motors, these devices are universal enough for most applications that require phase locked control. A precise reference frequency frequency dividers. The oscillator operates using a broad range of crystals, or, can function as a buffer stage to an external frequency source.

The UC1633 phase detector on these integrated circuits compares the reference frequency with a frequency/phase feedback signal. In the case of a motor, feedback is obtained at a hall output of other speed detection device. This signal is buffered by a sense ampilfier that squares up the ignal as it goes into the digital phase detector. The phase detector responds proportionally to the phase error between the reference and the sense amplifier output. This phase detector includes absolute frequency  steering to provide maximum drive signals when any frequency error exists. This feature allows optimum start-up and lock times to be realized.

Two op-amps are included that can be configured to provide necessary loop filtering. The outputs of the op-amps will source or sink in excess of 16mA, so they can provide a low impedence control signal to driving circuits.

Additional features include a double edge option on the sense amplifier that can be used to double the loop reference frequency for increased loop bandwidths. A digital lock signal is provided that indicates when there is zero frequency error, and a 5V reference output allows DC operating levels to be accurately set.