SBAU392A July 2022 – January 2023 AFE7950 , TRF1208
The green LED D3 should be lit at this point. D3 indicates that PLL loop 2 of the TRF1208 is locked. Optionally, the LED D4 indicates that PLL loop 1 of the TRF1208 is locked. If there are external equipment providing 10-MHz reference to the TRF1208 for lab equipment synchronization, then this LED D4 must be lit. The EVM is still functional without PLL loop 1 running, but PLL loop 2 is necessary for a successful bring-up.