+3V to +5.5V RS-232 Transceivers with AutoShutdown

Please check latest availability status for a specific part variant.


The MAX3221/MAX3223/MAX3243 achieve 1µA supply current with Maxim’s revolutionary AutoShutdown feature. When the MAX3221/MAX3223/MAX3243 do not sense a valid signal level on their receiver inputs, the on-board power supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system turns on again when a valid level is applied to any RS-232 receiver input.

The MAX3221/MAX3223/MAX3243 require only 0.1µF capacitors in 3.3V operation, and can operate from input voltages ranging from +3.0V to +5.5V.

A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply.

The MAX3221 is a 1-driver/1-receiver 16-pin SSOP version of the 20-pin 2-driver/2-receiver MAX3223.

The MAX3243 is a 3-driver/5-receiver with a complementary always-active receiver for external monitoring in a variety of 28 pin packages. Please see order information table for package offerings.

MAX3221, MAX3223, MAX3243: Typical Operating Circuit MAX3221, MAX3223, MAX3243: Typical Operating Circuit Enlarge+

Key Features

  • Integrated Charge Pump Circuitry Simplifies Power Requirements
    • Eliminates the Need for a ±12V Supply
    • Operation From a Single +3.3V or +5V Supply
  • 1µA Supply Current in Shutdown Mode Saves Power
    • AutoShutdown Feature is Enabled After No Activity on Receiver Inputs for 30μs
    • Software Control Option for Shutdown


  • Battery-Powered Equipment
  • Hand-Held Equipment
  • Peripherals
  • Portable Diagnostics Equipment
Part NumberVSUPPLY
TxRxData Rate
Internal Charge PumpExt. CapsCap. Value
Rx Active in ShutdnPackage/PinsBudgetary
mintypnomSee Notes
$1.75 @1k
MAX3223 222
$2.56 @1k
MAX3243 351
SOIC (W)/28
$4.45 @1k
See All RS-232 Line Driver/Receivers (136)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Technical Documents

App Note 4223 The Evolution of the RS-232 Transceivers
App Note 2588
Tutorial 2141 Determining Clock Accuracy Requirements for UART Communications
App Note 882 RS-232 Features Explained
App Note 588 Multiplexer Enables Pseudomultidrop RS-232 Transmission

Quality and Environmental Data

Product Reliability Reports: MAX3221.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

Additional Resources

RS232 Resources
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >


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