LINEAR TECHNOLOGY LTC2870, LTC2871, LTC2872 Technical data
LTC2870/LTC2871/LTC2872
LTC2870
LTC2872
LTC2871
Multiprotocol Transceivers
The LTC®2870/71/72 is a family of multiprotocol transceivers with switchable integrated termination for 3.3V and 5V systems.
These devices integrate pin-controlled termination resistors that automatically switch in or out to match the transceiver’s protocol
selection of RS232 or RS485, allowing for easy interface reconfiguration and elimination of external resistors and control relays.
The LTC2870 and LTC2871 can be configured as two RS232 single-ended transceivers or one RS485 differential transceiver on
shared (LTC2870) or dedicated (LTC2871) I/O lines, while the LTC2872 can be configured as four RS232 transceivers or two
RS485 transceivers, or combinations of both, on shared I/O lines. This on-the-fly configurability helps reduce component count for
multiprotocol networks.
Features
n
3V to 5.5V Supply Voltage Range
n
One RS485 or Two RS232 Transceivers per Port
n
20Mbps RS485 and 500kbps RS232
n
Automatic Selection of Integrated RS485 (120Ω)
and RS232 (5kΩ) Termination Resistors
n
Pin-Selectable Half- or Full-Duplex Mode RS485
Number of Ports 1 1 2
Possible Configurations
(RS485 Transceivers + RS232 Transceivers)
RS232 and RS485 I/O Pin Sharing per Port Shared Dedicated Shared
HBM ESD Rating ±26kV ±16kV ±16kV
Packages 4mm × 5mm QFN-28, TSSOP-28 5mm × 7mm QFN-38, TSSOP-38 5mm × 7mm QFN-38
0+0, 0+2, 1+0 0+0, 0+1, 0+2,
n
Logic Loopback Mode
n
High ESD: ±26kV (LTC2870) or ±16kV (LTC2871/LTC2872)
On Line I/O; ±4kV On All Other Pins
n
1.7V to 5.5V Logic Interface
n
Supports Up to 256 RS485 Nodes
n
Full Failsafe RS485 Receiver Eliminates UART Lockup
1+0, 1+1, 1+2
0+0, 0+2, 0+4,
1+0, 2+0, 1+2
L, LT, LTC, LTM, Linear Technology and the Linear logo are
registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Supported Data Rate
Multiprotocol Transceivers
Part
Number
# of
Drivers
# of
Receivers
Supply
(V)
Protocols Supported
RS232/
RS562
RS422/
RS485
V.35
(Async)
V.35
(Sync)
Termination
DCE or DTE Signals
Additional
Signals
ESD
(kV)
Temp
Grade
Packages
LTC1321 2 2 RS232, RS562, RS422, RS485 120kbps 10Mbps 10 C, I SW-24, N-24
LTC1322 4 4 ±5±5RS232, RS562, RS422, RS485 120kbps 10Mbps 4 C, I SW-24, N-24
LTC1323 2 3 ±5 LocalTalk, RS232, RS422 120kbps 2Mbps DTE Data, Control 4 SW-24, SO-24
LTC1334 4 4 5 RS232, RS562, RS422, RS485 120kbps 5Mbps 10 C, I SSOP-28,
SW-28, N-28
LTC1335 4 4 5 RS562, RS422, RS485 120kbps 10Mbps 4 C, I SW-24, N-24
LTC1343 4 4 5 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
LTC1344 5 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
LTC1344A 5 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
8Mbps 4Mbps DTE or DCE Data, Clock
or Control
•
•
LL, RL, TM 4 C, I SSOP-44
4 C, I SSOP-24
4 C, I SSOP-24
LTC1345 3 3 5 V.35 10Mbps 5Mbps DTE or DCE Data, Clock 4 C, I SW-28, N-28
LTC1346A 3 3 ±5 V.35 10Mbps 5Mbps DTE or DCE Data, Clock 4 C, I SW-24
LTC1387 2 2 5 RS232, RS562, RS422, RS485 128kbps
LTC1543 3 3 5 EIA530, EIA530-A, RS232,
150kbps
or 5Mbps
4 C, I SSOP-20,
SW-20
128kbps 10Mbps 10Mbps 5Mbps DTE or DCE Data, Clock 4 C, I SSOP-28
RS449, V.35, V.36, X.21
LTC1544 4 4 5 EIA530, EIA530-A, RS232,
128kbps 10Mbps 10Mbps 5Mbps DTE or DCE Control LL 4 C, I SSOP-28
RS449, V.35, V.36, X.21
LTC1545 5 5 5 EIA530, EIA530-A,
RS232,
128kbps 10Mbps 10Mbps 5Mbps DTE or DCE Control LL, RL, TM 4 C, I SSOP-36
RS449, V.35, V.36, X.21
LTC1546 3 3 5 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
LTC2844 4 4 3.3 EIA530, EIA530-A, RS232,
128kbps 10Mbps 10Mbps 5Mbps
DTE or DCE Data, Clock 2 C, I SSOP-28
•
128kbps 10Mbps 10Mbps 5Mbps DTE or DCE Control LL 4 C, I SSOP-28
RS449, V.35, V.36, X.21
LTC2845 5 5 3.3 EIA530, EIA530-A, RS232,
128kbps 10Mbps 10Mbps 5Mbps DTE or DCE Control LL, RL, TM 4 C, I SSOP-36
RS449, V.35, V.36, X.21
LTC2846 3 3 3.3 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
LTC2847 3 3 5 EIA530, EIA530-A, RS232,
RS449, V.35, V.36, X.21
LTC2870 2 2 3 to 5 RS232, RS485, RS422 500kbps 20Mbps
LTC2871 2 2 3 to 5 RS232, RS485, RS422 500kbps 20Mbps
LTC2872 4 4 3 to 5 RS232, RS485, RS422 500kbps 20Mbps
128kbps 10Mbps 10Mbps 5Mbps
128kbps 10Mbps 10Mbps 5Mbps
DTE or DCE Data, Clock 4 C, I SSOP-36
•
DTE or DCE Data, Clock 4 C, I QFN-38
•
DTE or DCE 26 C, I QFN-28,
•
DTE or DCE 16 C, I QFN-38,
•
DTE or DCE 16 C, I QFN-38
•
TSSOP-28
SSOP-38
LTC2872 Typical Applications
RS485 Mode with Duplex Control RS232 Mode Mixed Mode with RS485 Termination
SW
22µH
3V TO 5.5V1.7V TO V
2.2µF
V
CC
Y1
Z1
A1
B1
Y2
Z2
A2
B2
V
EE
CC
470nF
2.2µF
V
CAP
RS485
HALFFULL
DUPLEX
2.2µF 2.2µF
H/F
DY1
RA1
DY2
RA2
V
L
LTC2872
DD
22µH
3V TO 5.5V1.7V TO V
2.2µF
V
CC
2.2µF
CC
V
CAP SW
L
470nF
LTC2872
DY1
DZ1
RA1
RB1
DY2
DZ2
RA2
RB2
V
2.2µF 2.2µF
DD
Y1
Z1
A1
B1
Y2
Z2
A2
B2
V
EE
CC
470nF
2.2µF
V
CAP SW
RS485
ONOFF
TERMINATION
2.2µF 2.2µF
L
TE485-1
DY1
RA1
DY2
DZ2
RA2
RB2
V
DD
LTC2872
22µH
3V TO 5.5V1.7V TO V
120Ω
120Ω
2.2µF
V
CC
Y1
Z1
A1
B1
Y2
Z2
A2
B2
V
EE
www.linear.com/multiprotocol n 1-800-4-LINEAR
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