50 Mbps half-duplex RS-485 — what the data rate buys you
At that line rate it handles Profibus, DMX512, and other high-speed industrial fieldbuses where a 10 Mbps part would leave no timing margin. The single driver/receiver pair (1/1) suits point-to-point or multi-drop with one talker at a time.
80 mV hysteresis — noise margin on long cable runs
Receiver hysteresis is specified at 80 mV, which filters reflections and common-mode noise on cables that run tens of metres through a factory floor. Without that margin a 50 Mbps link would false-trigger on every stub reflection.
TI lists the SN65HVD78DRBT as Active. That means no last-time-buy window to chase, no risk of a forced redesign mid-production.