A 50 ppm error in the reference frequency produces a real time clocking error of 2 minutes per month and will not be suitable for time keeping applications. So the user must ensure that proper crystals are used with Cypress clock generators. For best results, a fundamental mode, parallel resonant crystal should be used.
For detailed explanation and analysis, please refer our Crystal Parameters Recommendation for Cypress Frequency Synthesizers whitepaper available on our website (please click on the link just provided). It describes crystal recommended for Cypress clock generators and concludes with an error budget analysis.
Following are the Crystal Specifications:
6pF-30pF capacitance (18pF typical).
drive level 500uW typical, max 2mW.
ESR < 25ohms.
Commercial or Industrial temperature depending on application.