Full-duplex operation with one driver and one receiver on-chip means a single MAX1485EUB+ handles both transmit and receive pairs for a point-to-point RS-422 link or a multi-drop RS-485 bus where the driver is always enabled on the transmit side.
250 kbps data rate and 70 mV hysteresis — the bus-margin trade-off
The 250 kbps data rate is the maximum signaling speed across the RS-485 bus — at this rate the cable length is limited by the rise-time degradation, not the driver itself. For runs beyond 4000 feet, dropping to 115.2 kbps or lower keeps the eye open. The 70 mV receiver hysteresis provides 70 mV of noise margin on the differential bus — enough to reject common-mode noise from a nearby motor drive or switching supply without adding external filtering. A standard RS-485 receiver without hysteresis would chatter on a noisy idle bus.
A panel that sees direct sunlight on a summer day stays below 85°C with passive ventilation.