Trim capacitors for the CY22392/3/4

Question: For the CY22392/3/4 devices, are trim capacitors required on either side of the crystal? When is this necessary?



The crystal oscillator capacitance is programmable on the CY22392/3/4. Using the CyberClocks configuration software, either a crystal or external reference source can be selected. If an external reference is chosen, it will automatically set the device to the lowest capacitance value, which is an equivalent of 6 pF total, or 12 pF on the Xin pin and 12 pF on the Xout pin. Also, the maximum capacitance value is 30 pF equivalent or 60 pF on the Xin and Xout pins.

The input load capacitors are placed on-die to reduce external component cost. These capacitors are true parallel-plate capacitors for ultra-linear performance. These were chosen to reduce the frequency shift that occurs when non-linear load capacitance interacts with load, bias, supply, and temperature changes