The NE565 and NE565C are general-purpose phase-locked loops containing a stable, highly linear voltage-controlled oscillator for low distortion FM demodulation and a double-balanced phase detector with good carrier suppression. The VCO frequency is set with an external resistor and capacitor, and a tuning range of 10:1 can be obtained with the same capacitor. The characteristics of the closed-loop system—bandwidth, response speed, capture, and pull-in range—may be adjusted over a wide range with an external resistor and capacitor. The loop may be broken between the VCO and the phase detector for the insertion of a digital frequency divider to obtain frequency multiplication.
