The datasheet is ambiguous regarding external clocking of TPS61178.
The "Pin Functions" table under "6 Pin Configuration and Functions" suggests that both models can be externally clocked. However, the parenthesis in "8.3.8 External Clock Synchronization (TPS611781)" would normally mean that only TPS611781 can be externally clocked.
But, the 6th posting in this thread seems to say that TPS61178 can be externally clocked:
So, can the TPS61178 be externally clocked? If so, what is the behaviour at light load? Only pulse skipping and not pulse frequency modulation?