Multiprotocol Transceivers The LTC®2870/71/72/73 are 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; the LTC2872 can be configured as four RS232 transceivers or two RS485 transceivers, or combinations of both, on shared I/O lines; the LTC2873 can be configured as one RS232 transceiver or one RS485 transceiver on shared I/O lines. Features 3V to 5.5V Supply Voltage Range Up to Two RS485 and Four RS232 Transceivers 20Mbps RS485 and 500kbps RS232 Automatic Selection of Integrated RS485 (120Ω) and RS232 (5kΩ) Termination Resistors Pin-Selectable Half- or Full-Duplex Mode RS485 n n n n n n n n n Logic Loopback Mode High ESD: Up to ±26kV on Bus I/O; ±4kV On All Other Pins 1.7V to 5.5V Logic Interface Supports Up to 256 RS485 Nodes Full Failsafe RS485 Receiver Eliminates UART Lockup n Dual Protocol (RS485/RS232) Transceivers LTC2870 LTC2871 LTC2872 LTC2873 0+0, 0+2, 1+0 0+0, 0+1, 0+2, 1+0, 1+1, 1+2 0+0, 0+2, 0+4, 1+0, 2+0, 1+2 0+0, 0+1, 1+0 RS232 and RS485 I/O Pin Sharing per Port Shared Dedicated Shared Shared HBM ESD Rating ±26kV ±16kV ±16kV ±26kV 4mm × 5mm QFN-28, TSSOP-28 5mm × 7mm QFN-38, TSSOP-38 5mm × 7mm QFN-38 4mm × 5mm QFN-24 Possible Configurations (RS485 Transceivers + RS232 Transceivers) Packages 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. Multiprotocol Transceivers Family Part Number LTC1321 LTC1322 LTC1323 LTC1334 LTC1335 LTC1343 # of # of Supply Drivers Receivers (V) Protocols Supported 2 2 ±5 RS232, RS562, RS422, RS485 4 4 ±5 RS232, RS562, RS422, RS485 2 3 ±5 LocalTalk, RS232, RS422 4 4 5 RS232, RS562, RS422, RS485 4 4 4 4 LTC1345 LTC1346A LTC1387 3 3 2 3 3 2 LTC1543 3 3 LTC1544 4 4 LTC1545 5 5 LTC1546 3 3 LTC2844 4 4 LTC2845 5 5 LTC2846 3 3 LTC2847 3 3 LTC2870 2 2 RS562, RS422, RS485 EIA530, EIA530-A, RS232, RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, RS449, V.35, V.36, X.21 5 V.35 ±5 V.35 5 RS232, RS562, RS422, RS485 128kbps 150kbps or 5Mbps 5 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 3.3 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 3.3 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 3.3 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 5 EIA530, EIA530-A, RS232, 128kbps 10Mbps RS449, V.35, V.36, X.21 3 to 5 RS232, RS485, RS422 500kbps 20Mbps LTC2871 3 3 3 to 5 RS232, RS485, RS422 LTC2872 LTC2873 4 1 4 1 3 to 5 RS232, RS485, RS422 3 to 5 RS232, RS485, RS422 LTC1344 LTC1344A 5 5 Supported Data Rate RS232/ RS422/ V.35 V.35 TermiAdditional ESD Temp. RS562 RS485 (Async) (Sync) nation DCE or DTE Signals Signals (kV) Grade Packages 120kbps 10Mbps 10 C, I SW-24, N-24 120kbps 10Mbps 10 C, I SW-24, N-24 120kbps 2Mbps DTE Data, Control 10 SW-24, SO-24 120kbps 5Mbps 10 C, I SSOP-28, SW-28, N-28 120kbps 10Mbps 10 C, I SW-24, N-24 8Mbps 4Mbps DTE or DCE Data, Clock LL, RL, TM 2 C, I SSOP-44 or Control • 2 C, I SSOP-24 • 2 C, I SSOP-24 10Mbps 5Mbps 10Mbps 5Mbps DTE or DCE DTE or DCE Data, Clock Data, Clock 10 10 6 C, I C, I C, I 10Mbps 5Mbps DTE or DCE Data, Clock 2 C, I SW-28, N-28 SSOP-24 SSOP-20, SW-20 SSOP-28 10Mbps 5Mbps DTE or DCE Control LL 2 C, I SSOP-28 10Mbps 5Mbps DTE or DCE Control LL, RL, TM 2 C, I SSOP-28 DTE or DCE Data, Clock 2 C, I SSOP-28 10Mbps 5Mbps DTE or DCE Control LL 1 C, I SSOP-28 10Mbps 5Mbps DTE or DCE Control LL, RL, TM 1 C, I SSOP-36 10Mbps 5Mbps • 10Mbps 5Mbps • DTE or DCE Data, Clock 2 C, I SSOP-36 10Mbps 5Mbps • DTE or DCE Data, Clock 1 C, I QFN-36 • DTE or DCE 26 500kbps 20Mbps • DTE or DCE 16 500kbps 20Mbps 500kbps 20Mbps • • DTE or DCE DTE or DCE 16 26 C, I, H QFN-28, TSSOP-28 C, I QFN-28, TSSOP-28 C, I QFN-38 C, I, H QFN-24 3500VRMS Isolated RS485/RS232 Transceiver 3V TO 5.5V RO 485/232 RS485 D R DI VCC1 VL1 ON1 OUTD INC INB INA EOUTD GND1 ISOLATION BARRIER LTM2892-S VCC2 VL2 ON2 IND INE INF OUTC OUTB OUTA EOUTA GND2 220nF ISOLATED 3V TO 5.5VIN 10μH 2.2μF 10k CAP VCC SW VL VDD SHDN 485/232 LTC2873 DE485/F232 VEE RE485 TE485 RS485 A/DO RO GND 1μF ISO 1μF ISO DI LB ISO 120Ω RS485 (485/232 HIGH) RS232 (485/232 LOW) B/RI RS232 5k ISO ISOLATED GND IN www.linear.com/multiprotocol n 1-800-4-LINEAR 1215B