Full-duplex RS-485/422 at 20 Mbps — the 3.3 V industrial bus line
The SN65HVD74DR: The 1/1 driver/receiver count means one differential pair handles transmit, the other handles receive — no direction pin to toggle, which simplifies the MCU GPIO budget on a full-duplex bus.
Receiver hysteresis and bus-fail margin
70 mV of receiver hysteresis filters noise on long cable runs — a differential bus with 100 m of twisted pair picks up common-mode transients from nearby VFDs; the hysteresis window keeps the output from chattering at the zero-crossing point. Full-duplex operation at 20 Mbps requires matched termination at both ends of the cable — the driver's rise time is fast enough that unterminated stubs cause reflections that exceed the hysteresis band and produce bit errors. The 8-SOIC footprint (3.90 mm width) fits a standard SOIC-8 layout with the termination resistors placed within 10 mm of the pins.
Active production — no end-of-life watch needed
The base product number 65HVD74 covers the wider family; the DR suffix denotes the 8-SOIC package on tape-and-reel or cut-tape. No pin-compatible second-source is listed in the official record, but the 3.3 V full-duplex RS-485 space has several functional equivalents from other vendors — confirm the BOM's exact supply voltage and data-rate requirement before substituting.