SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
The Device integrates both internal and external clock source options in RMII mode. However, the internal clock source option is UNSUPPORTED by the Device integration. Figure 5-23 presents the high level view of the two clocking options.
Figure 5-23(a) shows the UNSUPPORTED internal clock source for RMII clock. It is a 50 MHz clock source that is provided by the Device on the MCU_CLKOUT0 pin. This clock source routes on the PCB to both the Device MCU_RMII1_REF_CLK input and the external Phy RMII clock input.
Figure 5-23(b) shows the SUPPORTED external clock source option for the RMII clock. In this case a 50 MHz clock is available on the PCB (possibly from an oscillator or from the Ethernet Phy). This externally generated clock source is routed to both the Device MCU_RMII1_REF_CLK input and the external Phy RMII clock input. In both cases, the Device MCU_RMII1_REF_CLK is an input. The difference between the two cases is simply that in the UNSUPPORTED Figure 5-23(a) the Device provides a 50 MHz clock source on a separate pin.