When driving the following, Vivado synthesis implements inferred tristate buffers with different device primitives:
- An external pin of the circuit (OBUFT)
- An Internal bus (BUFT):
- Vivado synthesis converts automatically inferred BUFT to logic realized in LUTs.
- When an internal bus inferring a BUFT is driving an output of the top module, the Vivado synthesis infers an OBUF.