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
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
SP337E
3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER
REV. 1.0.2
F
IGURE
1. T
YPICAL
RS-232
AND
RS-485 A
PPLICATION
C
IRCUITS
ORDERING INFORMATION
P
ART
N
UMBER
SP337EBCT-L
SP337EBCY-L
SP337EBET-L
SP337EBEY-L
SP337EUCT-L
SP337EUCY-L
SP337EUET-L
SP337EUEY-L
P
ACKAGE
28-pin WSOIC
28-pin TSSOP
28-pin WSOIC
28-pin TSSOP
28-pin WSOIC
28-pin TSSOP
28-pin WSOIC
28-pin TSSOP
O
PERATING
T
EMPERATURE
R
ANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
D
EVICE
S
TATUS
Active
Active
Active
Active
Active
Active
Active
Active
2
SP337E
REV. 1.0.2
3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER
PIN DESCRIPTIONS
Pin Assignments
P
IN
#
P
IN
N
AME
T
YPE
D
ESCRIPTION
RS-232
T3 Driver TTL input
1
TI3
Input
RS-485/RS-422
T3 Driver TTL input
This pin has a 400k pull-up to Vcc in both RS-232 and RS-485 modes.
The pull-up is disabled in the SP337EU shutdown mode.
X*
Only RS-485 mode
2
TXEN
Input
This pin has a 400k pull-up to Vcc in both RS-232 and RS-485 modes.
The pull-up is disabled in the SP337EU shutdown mode.
X*
T3 Driver Output
T3(Z) Inverting Output
T3(Y) Non-Inverting Output
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
TX4
TX3
Vcc
TX1
TX2
GND
C1+
V+
C2+
C1-
C2-
V-
RI1
RI2
RI3
RI4
RX1
RX2
RX3
RX4
RX5
RI5
RS232/RS485
RXEN
Output
Output
Power
Output
Output
Power
Pump
Pump
Pump
Pump
Pump
Pump
Input
Input
Input
Input
Output
Output
Output
Output
Output
Input
Input
Input
Power Supply Voltage, between 3.3V and 5V
T1 Driver Output
T2 Driver Output
Ground
Positive Terminal of Positive Flying Capacitor
Vdd Storage Capacitor
Positive Terminal of Negative Flying Capacitor
Negative Terminal of Positive Flying Capacitor
Negative Terminal of Negative Flying Capacitor
Vss Storage Capacitor
R1 Receiver Input, 5k pull-down
R2 Receiver Input, 5k pull-down
R3 Receiver Input, 5k pull-down
R4 Receiver Input, 5k pull-down
R1(B) Receiver Inverting Input
R1(A) Receiver Non-Inverting Input
R3(A) Receiver Non-Inverting Input
R3(B) Receiver Inverting Input
T1(Y) Non-Inverting Output
T1(Z) Inverting Output
R1 Receiver Output
R2 Receiver Output
R3 Receiver Output
R4 Receiver Output
R5 Receiver Output
R5 Receiver Input, 5k pull-down
X*
X*
X*
X*
Mode select, either RS-232 (low) or RS-485/422 (high) mode
Receiver enable for both RS-232 and RS-485/422 mode (Active low)
3
SP337E
3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER
Pin Assignments
P
IN
#
P
IN
N
AME
T
YPE
D
ESCRIPTION
RS-232
T1 Driver Input
27
TI1
Input
RS-485/RS-422
T1 Driver Input
REV. 1.0.2
This pin has a 400k pull-up to Vcc in both RS-232 and RS-485 modes.
The pull-up is disabled in the SP337EU shutdown mode.
T2 Driver Input
X*
28
TI2
Input
This pin has a 400k pull-up to Vcc in both RS-232 and RS-485 modes.
The pull-up is disabled in the SP337EU shutdown mode.
Pins marked with an X in the above table are ignored or "don’t care" in the listed mode, provided
they do not exceed Vcc or go below ground. Some of these pins have a pull-up to Vcc which
remains active in both RS-232 and RS-485 mode, but is disabled in the SP337EU shutdown mode.
*
4
SP337E
REV. 1.0.2
3.3V TO 5V RS-232/RS-485/RS-422 MULTIPROTOCOL TRANSCEIVER
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections to the
specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability and cause permanent
damage to the device.
Supply Voltage V
CC
Receiver Input V
IN
(DC Input Voltage)
Input Voltage at TTL input Pins
Driver Output Voltage (from Ground)
Short Circuit Duration, TXout to GND
Storage Temperature Range
Lead Temperature (soldering, 10s)
Power Dissipation 28-pin SOIC-W
(derate 17mW/°C above +70°C)
Power Dissipation 28-pin TSSOP
(derate 12mW/°C above +70°C)
+6.0V
-16V to +16V
-0.3V to Vcc + 0.5V
-7.5V to +12.5V
Continuous
-65°C to + 150°C
+300°C
938mW
657mW
CAUTION:
ESD (Electrostatic Discharge) sensitive device. Permanent damage may occur on unconnected devices subject to high energy electrostatic fields. Unused
devices must be stored in conductive foam or shunts. Personnel should be properly grounded prior to handling this device. The protective foam should be
discharged to the destination socket before devices are removed.
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