The MAX3221CUE+T is part of Maxim's MAX3221/MAX3223/MAX3243 family of +3V to +5.5V RS-232 transceivers with AutoShutdown. The MAX3221 is the single-channel member - one transmitter and one receiver - ideal where only a single RS-232 link is needed and power must be minimal.

The revolutionary AutoShutdown feature senses the receiver inputs and, when the RS-232 cable is disconnected or the transmitters are disabled, automatically powers down the on-board supply and drivers to just 1µA. The system turns back on automatically when a valid RS-232 level is again applied - no software intervention needed, though software shutdown control is also available.

A dual charge pump generates the ±5.5V RS-232 line levels and the device needs only 0.1µF capacitors for 3.3V operation. AutoShutdown control is exposed on EN̅, FORCEON, FORCEOFF̅ and the INVALID̅ valid-signal-detect output. It suits battery-powered, hand-held and portable equipment in a 16-pin TSSOP.

Note: Refer to the official Maxim MAX3221/MAX3223/MAX3243 datasheet for full electrical parameters. Subject to change without notice; verify all parameters before final design.

The MAX3221CUE+T is supplied in a 16-pin TSSOP package, indicated by the CUE suffix; an SSOP option also exists. The small TSSOP suits space-constrained hand-held and portable designs.

The "+" suffix indicates lead-free, RoHS-compliant finish and the "T" suffix tape-and-reel packing. Standard 16-lead TSSOP land patterns and reflow profiles apply; place the four charge-pump capacitors and VCC bypass (0.1µF) close to the device. The diagram below shows the typical operating circuit.

The MAX3221 uses a 16-pin TSSOP/SSOP pinout (top view):

• Pin 1 - EN̅: Receiver enable, active-low (high tri-states the receiver output).
• Pin 2 - C1+ / Pin 4 - C1- / Pin 5 - C2+ / Pin 6 - C2-: Charge-pump capacitor connections.
• Pin 3 - V+ / Pin 7 - V-: Charge-pump outputs (+5.5V / -5.5V).
• Pin 8 - R1IN / Pin 9 - R1OUT: Receiver RS-232 input / TTL-CMOS output.
• Pin 11 - T1IN / Pin 13 - T1OUT: Transmitter TTL-CMOS input / RS-232 output.
• Pin 10 - INVALID̅: Valid-signal-detect output (to power-management unit).
• Pin 12 - FORCEON / Pin 16 - FORCEOFF̅: AutoShutdown override controls.
• Pin 14 - GND / Pin 15 - VCC: Ground and +3V-+5.5V supply.

For automatic operation tie FORCEON and FORCEOFF̅ high and let AutoShutdown manage power; use EN̅ to gate the receiver and read INVALID̅ for link status. Confirm the exact pin assignment against the datasheet image below before layout.

The following parts are listed for reference. Verify channel count, ESD and package before substituting.

Maxim Integrated, now part of Analog Devices (NASDAQ: ADI), pioneered low-power RS-232 with the AutoShutdown MAX3221/MAX3223/MAX3243 family. The single-channel MAX3221 brings true 3.3V RS-232 and 1µA standby to portable designs.

Maxim/ADI provides complete datasheets, application notes and long-term supply, with authorized distribution and technical support across China for both prototype and volume programs.