300 mV hysteresis — noise margin for long cable runs
The MAX3223EEUP+T: The receiver hysteresis is specified at 300 mV, which gives the input a clean switching threshold even when the signal has picked up ground shifts or crosstalk over a multi-meter RS-232 cable — a common pain point in electrically noisy industrial environments. Full-duplex operation means the TX and RX paths are independent, so the part can simultaneously transmit and receive on separate lines without a direction-control pin — a direct fit for standard RS-232 DTE/DCE connections.