XR34350 Datasheet, PDF (1/20 Pages) Exar Corporation – Internal Termination and Wide Output Swing

XR34350
RS-232/485/422 Serial Transceiver with
Internal Termination and Wide Output Swing
Description
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.
Typical Application
FEATURES
■■ 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 (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
■■ 1 driver, 1 receiver RS-485/RS-422
■■ High swing RS-232 driver outputs
(±10.0V no load)
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 40-pin 6mm x 6mm
QFN package
■■ Pin compatible with SP339E and SP338E
APPLICATIONS
■■ Dual protocol serial ports (RS-232 or
RS-485/RS-422)
■■ Industrial and process control equipment
■■ Point-of-sale equipment
■■ HVAC controls equipment
■■ Building security and automation
equipment
RS-232 or RS-485
UART
XR34350
Multi-Protocol
XCVR
Figure 1. Typical Application
REV1B
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