RS-232/RS-485/RS-422 Transceiver with Internal Termination

  • Pin selectable Cable Termination
  • No external resistors required for RS-485/422 termination and biasing
  • 3.3V or 5V Single Supply Operation
  • Robust ESD Protection on bus pins
    • ±15kV Human Body Model (HBM)
    • ±8kV IEC 61000-4-2 (Contact)
  • Max Data Rate of 20Mbps in RS-485/422 Modes and up to 1Mbps in RS-232 Modes
  • Pin selectable 250kbps Slew Limiting
  • 3 Drivers, 5 Receivers RS-232/V.28
  • 2 Drivers, 4 Receivers RS-485/422
    • Full, Half and Mixed Duplex Configurations
    • 1/8th Unit Load, up to 256 receivers on bus
  • RS-485/422 Enhanced Failsafe for open, shorted, or terminated but idle inputs
  • Space saving 6mm x 6mm QFN-40 Package
  • Pin compatible with SP339

  • Dual Protocol Serial Ports (RS-232 or RS-485/422)
  • Industrial Computers
  • Industrial and Process Control Equipment
  • Point-Of-Sale Equipment
  • Networking Equipment
  • HVAC Controls Equipment
  • Building Security and Automation Equipment

The SP338 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 eight 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-485/422 modes feature up to two drivers and four receivers (2TX/4RX) in half, full, and mixed 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-485/422 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 Human Body Model (HBM) and ±8kV IEC-61000-4-2 Contact. 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-485/422 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 SP338 operates from a single power supply, either 3.3V or 5V, with low idle current. The shutdown mode consumes less than 10μA for low power standby operation.

For technical support or help choosing a product please email Exar’s Serial Technical Support group at:  serialtechsupport@exar.com.

Part NumberPkg CodeRoHSMin
StatusBuy NowOrder Samples
SP338EER1-0A-EBBoard   Active

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. 
No. of Tx3/2
No. of Rx5/4
Data Rate (kbps)256/1M/20M
VCC (V)3.3 or 5
Typ. ICC (mA)2
ESD (kV)15
Supported ProtocolsRS-232, V.28, RS-485, RS-422, V.24
Technical Assets