RS-232 transceiver for the 5V serial port that needs to work in a noisy bay
The MAX211EEAI+T is a Maxim Integrated full-duplex RS-232 transceiver packing four drivers and five receivers into a 28-pin SSOP package. It operates from a single 4.5V to 5.5V supply and handles data rates up to 120 kbps. The 500 mV of receiver hysteresis gives it some noise margin on the receive lines, useful when the cable runs through a motor drive cabinet or past a switching supply. The industrial temperature range (-40°C to 85°C) covers factory-floor and outdoor telecom enclosures.
Driver and receiver count — sizing the BOM line count
Four drivers and five receivers means this part handles a full RS-232 port with handshake lines (TXD, RXD, RTS, CTS, DSR, DCD, DTR, RI) plus one extra receive line. If your design only needs three drivers and three receivers, you have spare channels for diagnostics or a second port. If you need five drivers, this part won't fit — step up to the MAX213 family which offers five drivers.
120 kbps data rate — what it means for the link budget
At 120 kbps this transceiver is comfortably faster than the original 20 kbps RS-232 limit but well below the multi-megabit rates of modern RS-485 or LVDS links. It handles 115200 baud with margin, which covers most terminal, modem, and industrial sensor traffic. If your application needs 1 Mbps or higher, this is the wrong part — look at the MAX3222 or MAX3232 families that run at 250 kbps or 1 Mbps.
Supply voltage and package — board-level fit
The 4.5V to 5.5V supply range means this part wants a regulated 5V rail. The 28-SSOP package (0.209" body width, 5.30 mm) is a common footprint.
Lifecycle and sourcing posture
The MAX211EEAI+T carries an Active lifecycle status from the manufacturer, so there is no near-term end-of-life concern for production planning. It is ROHS3 compliant.