The following spread spectrum parameters are programmable:
1. Spread spectrum modulation frequency: 30KHz to 120KHz
2. Spread profile: Lexmark (Hershey Kiss) or linear
3. Spread type: Down or center spread
4. Spread percentage: -0.25 to -5% for down spread, +/-0.125 to +/-2.5% for center spread
These parameters can be configured on-the-fly via the I2C interface (if available), but any I2C-reconfigured values will be replaced by programmed values from non-volatile memory after power reset. Apart from this, the spread spectrum feature can be turned on or off at the clock output during run time by using the SSON pin.
There is a white paper available on “Spread Spectrum Clock Generators for solving EMI”.
The CY254xx family includes the following part numbers: