The MAX3221 device provides the electrical interface between an asynchronous communication controller (UART) and an RS-232 serial-port connector. It integrates a dual charge pump that generates RS-232 voltage levels from a single low-voltage supply, enabling straightforward RS-232 connectivity in 3.3-V and 5-V embedded systems.

The device meets common RS-232 electrical requirements (TIA/EIA-232-F and ITU V.28) and provides robust ESD protection on RS-232 bus pins. Automatic power-down can disable the driver and reduce supply current when no valid RS-232 signal is present; the INVALID output can be used for link presence and receiver input validity indication.

Variant note: MAX3221 is available in SSOP (DB) and TSSOP (PW) packages. MAX3221IDBR denotes the industrial-temperature SSOP (DB) tape-and-reel option.

MAX3221IDBR is supplied in a DB (SSOP-16) surface-mount package and is specified for the industrial temperature range (-40°C to +85°C). Always verify land pattern and mechanical dimensions using the official package drawing before PCB release.

The 16-pin package integrates logic-side I/O, RS-232 receiver/driver pins, charge-pump capacitor connections (C1+/C1−, C2+/C2−), generated rails (V+ and V−), and control/status pins (EN, FORCEON, FORCEOFF, INVALID). Refer to the datasheet pin table for exact pin numbers for the DB package.

• EN: Receiver enable (controls ROUT output state)
• DIN: Driver input (logic side)
• DOUT: RS-232 driver output
• RIN: RS-232 receiver input
• ROUT: Receiver output (logic side)
• FORCEON / FORCEOFF: Automatic power-down control inputs
• INVALID: Status output indicating receiver input validity
• C1+, C1−, C2+, C2−: Charge-pump capacitor pins (use 0.1 μF capacitors)
• V+: Positive rail generated by the charge pump
• V−: Negative rail generated by the charge pump
• VCC: 3-V to 5.5-V supply voltage
• GND: Ground

When selecting substitutes, compare channel count, data rate, ESD level, automatic power-down behavior, and package compatibility. Always verify pin functions and capacitor requirements before approving alternates for production.

• SNx5C3221 - Pin-compatible higher-speed option (up to 1 Mbps)
• MAX3221IPWR - Same function in TSSOP (PW) package (verify footprint)
• MAX3221CDBR - Commercial temperature option (0°C to +70°C)

Note: Always confirm footprint compatibility, control-pin behavior, and ESD rating against official documentation before replacement approval.

Texas Instruments (TI) supplies analog and embedded semiconductor solutions used across industrial, automotive, communications, and computing markets. The MAX3221 family delivers single-supply RS-232 connectivity with robust ESD protection and flexible power-management features for embedded systems.