Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
SP3495E-3497E
HIGH SPEED +3.3V RS-485/RS-422 TRANSCEIVERS WITH +/-15KV ESD PROTECTION AND
ADVANCED FAILSAFE
MAY 2009 REV. 1.0.0
GENERAL DESCRIPTION
The SP3495E - SP3497E transceivers are suitable
for high speed bidirectional communication on
multipoint bus transmission lines. They are designed
for balanced data transmission and comply with both
RS-485 and RS-422 EIA standards. Each device
contains one differential driver and one differential
receiver
Driver differential outputs and receiver differential
inputs are connected internally to form a half-duplex
input/output to the RS-485 bus. Separate RE
and DE
pins enable and disable the driver and receiver
independently or may be externally connected
together as a direct control. The device enters a low
power shutdown mode if both driver and receiver are
disabled. the bus-pin outputs of disabled or powered
down devices are in high impedance state. The high
impedance driver output is maintained over the entire
common-mode voltage range of -7V to +12V.
SP3495E - SP3497E operates from a single 3.3V
power supply. SP3495E - SP3497E transceivers load
the data bus only half as much as a standard RS-485
unit load. This allows up to 64 devices to be
connected simultaneously on a bus without violating
required RS-485 signal margin and without using
repeaters. Excessive power dissipation caused by
bus contention or by shorting outputs to ground or a
voltage source is prevented by short circuit protection
and thermal shutdown. This feature forces the driver
output into high impedance state if the absolute value
of the output current exceeds 250mA or if junction
temperature exceeds 165°C. Receivers will fail-safe
to a logic high output state if the inputs are
unconnected (floating) or shorted. All RS-485 inputs
and outputs are ESD protected up to +/-15kV Human
Body Model.
FEATURES
• 3.3V Single Supply Operation
• High Speed up to 32Mbps
• Robust +/-15kV ESD protection
• Hot Swap glitch protection
• Advanced Fail-safe Receiver Inputs
• Half Unit Load, 64 Transceivers on bus
• Driver short circuit current limit and thermal
shutdown for overload protection
• Low Current 1uA shutdown mode
TYPICAL APPLICATIONS
• Factory Automation Controls
• Motor Control
• Industrial Process Control
• Building Automation
• Security Systems
• Remote Utility Meter Reading
• Long or un-terminated transmission lines
F
IGURE 1. TYPICAL APPLICATION CIRCUIT
