FeaTures
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Four RS232 and Two RS485 Transceivers
3V to 5.5V Supply Voltage
20Mbps RS485 and 500kbps RS232
Automatic Selection of Integrated RS485 (120Ω)
and RS232 (5kΩ) Termination Resistors
Half-/Full-Duplex RS485 Switching
Logic Loopback Mode
High ESD: ±16kV on Line I/O
1.7V to 5.5V Logic Interface
Supports Up to 256 RS485 Nodes
RS485 Receiver Full Failsafe Eliminates UART Lockup
Available in 38-Pin 5mm
×
7mm QFN Package
Flexible RS232/RS485/RS422 Interface
Software Selectable Multiprotocol Interface Ports
Point-of-Sale Terminals
Cable Repeaters
Protocol Translators
PROFIBUS-DP Networks
LTC2872
RS232/RS485 Dual
Multiprotocol Transceiver
with Integrated Termination
DescripTion
The LTC
®
2872 is a robust pin-configurable transceiver
that supports RS232, RS485, and RS422 standards while
operating on a single 3V to 5.5V supply. The LTC2872 can
be configured as four RS232 single-ended transceivers
or two RS485 differential transceivers, or combinations
of both, on shared I/O lines.
Pin-controlled integrated termination resistors allow
for easy interface reconfiguration, eliminating external
resistors and control relays. Half-duplex switches allow
four-wire and two-wire RS485 configurations. Loopback
mode steers the driver inputs to the receiver outputs for
diagnostic self-test. The RS485 receivers support up to
256 nodes per bus, and feature full failsafe operation for
floating, shorted or terminated inputs.
An integrated DC/DC boost converter uses a small induc-
tor and one capacitor, eliminating the need for multiple
supplies for driving RS232 levels.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
applicaTions
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Typical applicaTions
RS485 Mode with Duplex Control
1.7V TO V
CC
2.2µF
RS485
FULL HALF
DUPLEX
V
L
CAP
H/F
DY1
Z1
DZ1
RA1
RB1
DY2
DZ2
RA2
RB2
V
DD
2.2µF
2.2µF
Z1
A1
B1
Y2
Z2
A2
B2
V
EE
2.2µF
2.2µF
DY2
DZ2
RA2
RB2
V
DD
SW
LTC2872
Y1
DY1
V
CC
470nF
3V TO 5.5V
22µH
2.2µF
2.2µF
V
L
CAP
SW
LTC2872
Y1
V
CC
RS485
OFF ON
TERMINATION
DY1
RS232 Mode
1.7V TO V
CC
470nF
3V TO 5.5V
22µH
2.2µF
Mixed Mode with RS485 Termination
1.7V TO V
CC
2.2µF
V
L
CAP
TE485-1
SW
LTC2872
Y1
120Ω
Z1
A1
RA1
120Ω
B1
Y2
Z2
A2
B2
V
EE
2872 TA01
470nF
3V TO 5.5V
22µH
2.2µF
V
CC
RA1
A1
B1
Y2
Z2
DY2
RA2
V
DD
2.2µF
A2
B2
V
EE
2.2µF
2872f
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LINEAR [ LINEAR INTEGRATED SYSTEMS ]
