SP337EBEY-L Datasheet, PDF (1/18 Pages) Exar Corporation – 3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER

SP337E
3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER
MARCH 2011
REV. 1.0.2
GENERAL DESCRIPTION
The SP337E is a dual mode serial transceiver
containing both RS-232 and RS-485/422 line drivers
and receivers. The RS-232 mode provides three
drivers and five receivers to support all eight signals
commonly used in the DB9 serial port connector
(3TX/5RX). In RS-485 mode the device features two
independent high speed RS-485/422 transmit and
receive channels (2TX/2RX). The default RS-485
configuration is full-duplex, but half-duplex operation
can be obtained by tying together the TX and RI pins,
and the TXEN and RXEN signals.
The SP337E is pin compatible to Exar’s SP334.
The SP337EB features a maximum data rate of
250kbps in RS-232 mode and a maximum data rate
of 15Mbps in RS-485. However, the SP337EU
features a maximum data rate of 1Mbps in RS-232
mode and a maximum data rate of 15Mbps in RS-485
mode.
The Exar-patented high efficiency charge pumps
(5,306,954) deliver true RS-232 driver output
voltages from a single power supply from 3.3V to 5V.
Charge pump outputs are self-monitored to minimize
power consumption. The SP337E requires only four
0.1μF capacitors for complete functionality.
All RS-485 receivers or transceivers feature high
impedance inputs which allow up to 256 transceivers
on a single shared bus. When configured in RS-485
mode, each driver may be individually enabled or put
into tri-state, simplifying use on shared buses or for
bidirectional communication. The RS-485/422 drivers
can be disabled (high-Z output) by the TXEN enable
pin. The RS-232 receiver outputs can be disabled by
the RXEN enable pin.
All receivers have advanced failsafe protection to
prevent oscillation when inputs are un-connected. In
RS-232 mode, each receiver input has a 5kΩ pull-
down to ground. in RS-485 mode, receivers will
default to output logic 1 if inputs are floating, shorted,
or open but terminated.
All driver outputs and receiver inputs are protected
against ESD strikes up to +/-15,000 volts.
FEATURES
• 3.3V to 5V Single Supply Operation
• Robust +/-15kV ESD Protection
■ Human Body Model
• Max Data Rate of 15Mbps in RS-485 mode
and up to 1Mbps in RS-232 mode (SP337EU)
• 3 Drivers, 5 Receivers RS-232/V.28
• 2 Drivers, 2 Receivers RS-485/RS-422
■ Full-Duplex Configuration
■ 1/8th Unit Load, up to 256 receivers on bus
• RS-485 Advanced Failsafe on Open, Short or
Terminated Lines
• Full Differential Driver Tri-State (Hi-Z) Control
• Receiver Output Tri-State Control
• WSOIC-28 or TSSOP-28 Package
TYPICAL APPLICATIONS
• Dual Protocol Serial Ports (RS-232 or RS-485)
• Industrial Computers
• Industrial and Process Control Equipment
• Point-Of-Sales Equipment
• Networking Equipment
• HVAC Controls Equipment
• Building Security Equipment
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com