Datasheet

LTC2872
1
2872f
Typical applicaTions
DescripTion
RS232/RS485 Dual
Multiprotocol Transceiver
with Integrated Termination
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.
RS485 Mode with Duplex Control
FeaTures
applicaTions
n
Four RS232 and Two RS485 Transceivers
n
3V to 5.5V Supply Voltage
n
20Mbps RS485 and 500kbps RS232
n
Automatic Selection of Integrated RS485 (120Ω)
and RS232 (5kΩ) Termination Resistors
n
Half-/Full-Duplex RS485 Switching
n
Logic Loopback Mode
n
High ESD: ±16kV on Line I/O
n
1.7V to 5.5V Logic Interface
n
Supports Up to 256 RS485 Nodes
n
RS485 Receiver Full Failsafe Eliminates UART Lockup
n
Available in 38-Pin 5mm × 7mm QFN Package
n
Flexible RS232/RS485/RS422 Interface
n
Software Selectable Multiprotocol Interface Ports
n
Point-of-Sale Terminals
n
Cable Repeaters
n
Protocol Translators
n
PROFIBUS-DP Networks
RS232 Mode Mixed Mode with RS485 Termination
2872 TA01
LTC2872
3V TO 5.5V1.7V TO V
CC
RS485
TERMINATION
H/F
DY1
2.2µF
Y1
Z1
A2
B2
A1
B1
RA1
DY2
RA2
V
DD
V
EE
DY1
DY2
RB2
RA2
DZ2
RB1
RA1
DZ1
Y1
B2
A2
Z1
Y2
Z2
A1
B1
LTC2872
DY2
RB2
RA2
DZ2
B2
A2
Y2
Z2
Y1
Z1
DY1
TE485-1
LTC2872
120Ω
ONOFF
RS485
DUPLEX
HALFFULL
Y2
Z2
A1
B1
RA1
120Ω
V
L
V
CC
CAP
470nF
22µH
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF
2.2µF2.2µF 2.2µF 2.2µF
SW
3V TO 5.5V1.7V TO V
CC
2.2µF
V
DD
V
EE
V
L
V
CC
CAP
470nF
22µH
SW
3V TO 5.5V1.7V TO V
CC
2.2µF
V
DD
V
EE
V
L
V
CC
CAP
470nF
22µH
SW
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