The CY2291, CY2292 and CY2295 are three-PLL frequency synthesizers that utilize EPROM technology. Many different programmable output frequencies and power saving features are contained in one small package. These features result inflexibility and cost savings, as well as short sample and productionlead times.This document begins with an explanation of the CY2291 features.The internal architecture and common applications are then presented. At that point, some recommendations about layout and filtering techniques are made. Finally, the Configuration Request Form is discussed in detail.Although this application note specifically references the CY2291, the information presented also applies to the CY2292 and the CY2295. The only differences are that the CY2295 comes in a 28 pin SSOP package and the CY2292comes in a 16-pin SOIC package (32XIN, 32XOUT, 32K, and VBATT are absent and the FLOPPYCLK output has been replaced with a GND pin on the CY2292).