MAX3221EUE+

MAX3221EUE+ is Maxim’s single‑channel RS‑232 transceiver. It lets a microcontroller UART talk to RS‑232 devices and vice versa. Key points:
- One driver (TTL/CMOS input to RS‑232 output) and one receiver (RS‑232 input to TTL/CMOS output).
- Single-supply operation from about 3.0 to 5.5 V; uses a charge pump to generate RS‑232 voltage levels.
- Low‑power, 8‑pin package; EUE+ indicates RoHS-compliant, extended‑temperature variant.
- Typical use: connect a MCU to a PC/modem serial port with a simple, single‑supply interface.
- Pinout just needs TX, RX, VCC, GND (plus any pump connections per package).
Note: exact baud-rate capability, RS‑232 voltage levels, and any external capacitor requirements vary by package variant—consult the MAX3221EUE+ datasheet for precise specs.

Equivalent 2-channel RS-232 transceivers from other makers include TI SN75C3221/SN75C3223, Analog Devices ADM3221/ADM3222/ADM3223, Exar Renesas SP3221/SP3223, and STMicroelectronics ST232/ST3232 (also consider MAX3232 as a drop-in).

Here are the typical features of the MAX3221EUE+ RS-232 transceiver:
- 1-channel RS-232 transceiver (one driver and one receiver) in a single device
- Single-supply operation from 3.0 V to 5.5 V (no dual supplies needed)
- On-chip charge pump to generate RS-232 level voltages (no external negative supply)
- TTL/CMOS logic-compatible TX input and RX output
- RS-232 compliant I/O levels with standard ±voltage swings
- Suitable for industrial/extended temperature applications (E or UE+ variants)
- Fast switching for moderate data rates (typical hundreds of kbps range)
- Low quiescent current; compact packaging options
- ESD protection on RS-232 and logic pins
Note: exact I/O voltage swings, data-rate ceiling, and temperature range can vary by package/suffix; please consult the datasheet for precise specifications.

- Pin count: 20 pins (SSOP/TSSOP-20).
- Function: Dual RS-232 transceiver (two drivers and two receivers) that converts TTL/CMOS UART signals to RS-232 levels and RS-232 levels to TTL, using an internal charge-pump to generate ± voltages from 5V (requires external capacitors).

Analog Devices (ADI). ADI acquired Maxim Integrated, and MAX3221EUE+ comes from Maxim’s product line.
ADI is a multinational semiconductor company that designs and manufactures analog, mixed-signal, and DSP integrated circuits for data conversion, signal processing, and interface applications.

- RS-232 interface for microcontrollers/embedded systems (MCUs to PCs, modems, printers)
- Embedded, instrumentation, data acquisition, and telemetry systems
- Industrial automation and factory equipment
- Networking gear console ports and test/measurement equipment
- Point-of-sale terminals and barcode scanners
- Battery-powered portable devices using single-supply operation (3.3V/5V), with extended temperature environments (-40°C to +85°C)
Note: MAX3221EUE+ is a low-power RS-232 transceiver with internal charge pumps for RS-232 level generation.

16-pin small-outline package (SO-16 / SOP-16).