RS-232/RS-485/RS-422 Serial Transceiver with Internal Termination and Wide Output Swing


The XR34350 is an advanced multiprotocol transceiver supporting RS-232, RS-485 and RS-422 serial standards in a 40-pin QFN package. Integrated cable termination and four configuration modes allow all three protocols to be used interchangeably over a single cable or connector with no additional switching components. Full operation requires only four external charge pump capacitors.

The RS-485/RS-422 modes feature one driver and one receiver (1Tx/1Rx) in both half and full duplex configurations. The RS-232 mode (3Tx/5Rx) provides full support of all eight signals commonly used with the DB9 RS-232 connector. A dedicated diagnostic loopback mode is also provided.

The high speed drivers operate up to 20Mbps in RS-485/RS-422 modes, and up to 1Mbps in RS-232 mode. All drivers can be slew limited to 250kbps in any mode to minimize electromagnetic interference (EMI).

All transmitter outputs and receiver inputs feature robust electrostatic discharge (ESD) protection to ±15kV IEC-61000-4-2 Air Gap, ±8kV IEC-61000-4-2 contact and ±15kV Human Body Model (HBM). Each receiver output has full fail-safe protection to avoid system lockup, oscillation, or indeterminate states by defaulting to logic-high output level when the inputs are open, shorted, or terminated but undriven. No external biasing resistors are required.

The RS-232 receiver inputs include a 5kΩ pull-down to ground. The RS-485/RS-422 receiver inputs are high impedance (>96kΩ when termination is disabled), allowing up to 256 devices on a single communication bus (1/8th unit load). The XR34350 operates from a single power supply, either 3.3V or 5V, with low idle current (2mA typical in all modes). The shutdown mode consumes less than 10μA for low power standby operation.

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  • Rx enabled during Tx short circuit condition
  • Pin selectable cable termination
  • No external resistors required for RS-485/RS-422 termination and biasing
  • 3.3V or 5V single supply operation
  • Robust ESD protection on bus pins
    • ±15kV IEC 61000-4-2 (Air Gap)
    • ± 8kV IEC 61000-4-2 (Contact)
    • ±15kV Human Body Model (HBM)
  • Max data rate of 20Mbps in RS-485/RS-422 modes and up to 1Mbps in RS-232 modes
  • Pin selectable 250kbps slew limiting
  • 3 drivers, 5 receivers RS-232/V.28
  • High swing RS-232 driver outputs (±10V no load)
  • 1 driver, 1 receiver RS-485/RS-422
    • Full and half duplex configuration
    • 1/8th unit load, up to 256 receivers on bus
  • RS-485/RS-422 enhanced failsafe for open, shorted, or terminated but idle inputs
  • Space saving 6mm x 6mm QFN-40 package
  • Pin compatible with SP339E and SP338E


  • Software programmable serial ports (RS-232 or RS-485/RS-422)
  • Industrial and single board computers
  • Industrial and process control equipment
  • HVAC controls
  • Building security and automation equipment
  • Point-of-Sale (POS) equipment

Design Tools


Pkg Code Details Quantities Dimensions PDF
QFN40 6x6 OPT1
  • JEDEC Reference: MO-220
  • MSL Pb-Free: L3 @ 260ºC
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 32.3ºC/W
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 490
  • Quantity per Reel: 3000
  • Quantity per Tube: n/a
  • Quantity per Tray: 490
  • Reel Size (Dia. x Width x Pitch): 330 x 16 x 12
  • Tape & Reel Unit Orientation: Quadrant 1
  • Dimensions: mm
  • Length: 6.00
  • Width: 6.00
  • Thickness: 1.00
  • Lead Pitch: 0.50

Parts & Purchasing

Part Number Pkg Code RoHS Min Temp Max Temp Status Buy Now Order Samples
XR34350IL QFN40 6x6 OPT1 -40 85 Active
XR34350ILTR QFN40 6x6 OPT1 -40 85 Active
XR34350ILEVB Board Active
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Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.
Distribution Date Description File
07/21/2017 Qualification of alternate assembly subcon, ANST. PCN 17-0626-01 ANST-1033.pdf
01/05/2017 Addition of an alternate qualified location, ANST, China. PCN 16-0835-01 ANST-1033.pdf