SPRZ575 March 2024 AM67 , AM67A , TDA4AEN-Q1 , TDA4VEN-Q1
PCIe: MAIN_PLLx operating in fractional mode, which is required for enabling SSC, is not compliant with PCIe Refclk jitter limits
The MAIN_PLLx, which optionally supplies the 100MHz PCIe Refclk for SERDES and external components, does not comply to the PCIe Refclk jitter limits when configured in fractional mode. Fractional mode is required for enabling SSC, therefore SSC mode is not compliant to the PCIe Refclk jitter limits.
When sourcing the 100MHz PCIe Refclk from the MAIN_PLLx, the MAIN_PLLx should be configured in integer mode only. This prevents the use of SSC for PCIe Refclk, which requires the PLL to operate in fractional mode. If SSC is required on the PCIe interface, an external Refclk generator with SSC should be used to provide the SERDES 100MHz Refclk.