LTC2873
Single-Bus RS485/RS232
Multiprotocol Transceiver with
Switchable Termination
FEATURES DESCRIPTION
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One RS485 or One RS232 Transceiver The LTC 2873 is a robust pin-configurable multiprotocol
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3V to 5.5V Supply Voltage transceiver that supports RS232, RS485, and RS422
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Up to 20Mbps RS485 protocols while operating on a single 3V to 5.5V supply.
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Slew-Controlled RS232 Operation: The LTC2873 can be configured as a half-duplex RS485
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Selectable 1Mbps or 250kbps transceiver or as an RS232 transceiver using the same
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Automatic Selection of Integrated RS485 (120) two bus pins.
and RS232 (5k) Termination Resistors
A pin-controlled integrated termination resistor allows for
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High ESD: 26kV HBM
easy interface reconfiguration, eliminating external resis-
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Logic Loopback Mode
tors and control relays. Loopback mode steers the driver
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1.7V to 5.5V Logic Interface
inputs to the receiver outputs for diagnostic self-test.
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Supports Up to 256 RS485 Nodes
The RS485 receiver supports up to 256 nodes per bus,
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RS485 Receiver Failsafe Eliminates UART Lockup
and features full failsafe operation for floating, shorted or
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H-Grade Available (40C to 125C)
terminated inputs.
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Available in 24-Pin 4mm 5mm QFN Package
An integrated DC/DC boost converter uses a tiny
2mm1.6mm inductor and one capacitor, eliminating
APPLICATIONS
the need for multiple supplies when driving RS232 levels.
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All registered trademarks and trademarks are the property of their respective owners.
Software Selectable RS232/RS485/RS422 Interface
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Industrial Sensors and Actuators
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Alarm Systems
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Traffic Control and Monitoring
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Highway Signs and Jumbo Displays
TYPICAL APPLICATION
220nF
10H
1.7V TO V 3V TO 5.5V
CC
2.2F
1F
RS485/RS232 Mode Switching
LTC2873
V CAP SW V
L CC
RS485 RS232
RS485
SHDN
(485/232 (485/232
DI
HIGH) LOW)
DI
DATA IN
A/DO
485/232 RS232
RS485
5V/DIV
B/RI
120
RO
DATA OUT
B/RI
485/232 485/232
V
DD
1F A/DO
RE485
RS232
D/R 3V/DIV
TE485
(485)
5k
DE485/
V
EE
F232
1F
LB
2873 TA01b
GND
1s/DIV
2873 TA01
REV B
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ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Notes 1 and 2)
TOP VIEW
Input Supplies
V , V .................................................... 0.3V to 7V
CC L
Generated Supplies
24 23 22 21 20
V ................................................ V 0.3V to 7.5V
V 1 19 NC
DD CC
EE
RO 2 18
V .........................................................7.5V to 0.3V V
CC
EE
485/232 3 17 A/DO
SW ............................................... 0.3V to (V + 0.3V)
DD
25
RE485 4 16 GND
CAP ................................................. (V 0.3V) to 0.3V V
EE
EE
DE485/F232 5 15 B/RI
A/DO, B/RI ...................................................15V to 15V
DI 6 14 V
CC
DI, 485/232, DE485/F232, RE485,
SHDN 7 13
V
DD
8 9 10 11 12
TE485, LB ................................................ 0.3V to 7V
SHDN, RO .......................................0.3V to (V + 0.3V)
L
Differential Terminator Voltage (Enabled)
UFD PACKAGE
(A/DO to B/RI) ..................................................... 6V
24-LEAD (4mm 5mm) PLASTIC QFN
Differential Terminator Voltage (Disabled)
T = 150C, = 43C/W
JMAX JA
(A/DO to B/RI) ................................................... 30V
EXPOSED PAD (PIN 25) IS V , MUST BE SOLDERED TO PCB
EE
Operating Temperature
LTC2873C ............................................... 0C to 70C
LTC2873I .............................................40C to 85C
LTC2873H .......................................... 40C to 125C
Storage Temperature Range .................. 65C to 150C
ORDER INFORMATION