XR3170E Datasheet, PDF (1/24 Pages) Exar Corporation – 3.3V High Speed RS-485/RS-422 TRANSCEIVERS WITH 1/8 UNIT LOAD

XR3170E-3178E
3.3V HIGH SPEED RS-485/RS-422 TRANSCEIVERS WITH 1/8^th UNIT LOAD
DECEMBER 2009
REV. 1.0.0
GENERAL DESCRIPTION
FEATURES
The XR3170E - XR3178E family of RS-485 devices
are designed for reliable, bidirectional communication
on multipoint bus transmission lines. Each device
contains one differential driver and one differential
receiver. XR3172E, XR3175E and XR3178E are half-
duplex devices; other part numbers are full-duplex.
All devices comply with TIA/EIA-485 and TIA/EIA-422
standards. Lead free and RoHS compliant packages
are available for all models.
These devices are ruggedized for use in harsh
operating conditions over the entire common-mode
voltage range from -7V to +12V. Receivers are
specially designed to fail-safe to a logic high output
state if the inputs are left un-driven or shorted. All RS-
485 bus pins are protected against severe ESD
events up to +/-15kV (Air-Gap and Human Body
Model) and up to +/-8kV Contact Discharge (IEC
61000-4-2). Drivers are protected from excess
current flow caused by bus contention or output
short-circuits by both an internal current limit and a
thermal-overload shutdown. Devices are rated for
Industrial (-40 to +85°C) operating temperatures.
Receivers have exceptionally high input impedance,
which places only 1/8^th the standard load on a shared
bus. Up to 256 transceivers may coexist while
preserving full signal margin.
All devices operate from a single 3.3V power supply
and draw negligible quiescent power. All versions
except the XR3171E, XR3174E and XR3177E may
independently enable and disable their driver and
receiver and enter a low power shutdown mode if
both driver and receiver are disabled. All outputs
maintain high impedance in shutdown or when
powered off.
• 3.3V Single Supply Operation
• High Speed 20Mbps Data Rate
• Slew Rate Limited - 250kbps And 500kbps Data
Rate
• 1/8^th Unit Load, 256 Transceivers On Bus
• Enhanced Failsafe For Receiver - Open, Short Or
Terminated Lines
• Robust ESD Protection For RS-485 Pins
■ +/-15kV Air-Gap Discharge
■ +/-15kV Human Body Model
■ +/-8kV Contact Discharge
• Hot Swap Glitch Protection
• Driver Short Circuit Current Limit And Thermal
Shutdown For Overload Protection
• Ultra-Low 650uA Quiescent Current
• 1µA Shutdown Mode
• Industry Standard Package Footprints
TYPICAL APPLICATIONS
• Motor Control
• Building Automation
• Security Systems
• Remote Utility Meter Reading
• Long Or Un-Terminated Transmission Lines
FIGURE 1. TYPICAL APPLICATION CIRCUIT
DE
XR3178E
B
DI
RT
A
RO
B
STUB
A
DE
XR3178E
B
RT
DI
A
RO
B
A
RE
DE
RE ^DE
RE
RE
DI
RO
DI
RO
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com