LTC2870/LTC2871 RS232/RS485 Multiprotocol Transceivers with Integrated Termination Fea T Descrip T n The LTC 2870/LTC2871 are robust pin-configurable mul- One RS485 and Two RS232 Transceivers n tiprotocol transceivers, supporting RS232, RS485, and 3V to 5.5V Supply Voltage n RS422 protocols, operating on a single 3V to 5.5V supply. 20Mbps RS485 and 500kbps RS232 n The LTC2870 can be configured as two RS232 single- Automatic Selection of Integrated RS485 (120) ended transceivers or one RS485 differential transceiver and RS232 (5k)Termination Resistors n on shared I/O lines. The LTC2871 offers independent con- Half-/Full-Duplex RS485 Switching n trol of two RS232 transceivers and one RS485 transceiver, High ESD: 26kV (LTC2870), 16kV (LTC2871) n each on dedicated I/O lines. Logic Loopback Mode n 1.7V to 5.5V Logic Interface Pin-controlled integrated termination resistors allow n Supports Up to 256 RS485 Nodes for easy interface reconfiguration, eliminating external n RS485 Receiver Failsafe Eliminates UART Lockup resistors and control relays. Half-duplex switches allow n H-Grade Available for the LTC2870 (40C to 125C) four-wire and two-wire RS485 configurations. Loopback n Available in 28-Pin 4mm 5mm QFN and mode steers the driver inputs to the receiver outputs for TSSOP (LTC2870), and 38-Pin 5mm 7mm QFN diagnostic self-test.The RS485 receivers support up to and TSSOP (LTC2871) 256 nodes per bus, and feature full failsafe operation for floating, shorted or terminated inputs. a T An integrated DC/DC boost converter uses a tiny n Software Selectable RS232/RS485/RS422 Interface 2mm1.6mm inductor and one capacitor, eliminating n Point-of-Sale Terminals the need for multiple supplies for driving RS232 levels. n Cable Repeaters L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog n Protocol Translators Devices, Inc. All other trademarks are the property of their respective owners. Typical a T Protocol Switching with Simultaneous Protocols and RS485 Duplex Switching Automatic Termination Selection RS485 Termination Switching 1.7V TO V 3V TO 5.5V 1.7V TO V 3V TO 5.5V 1.7V TO V 3V TO 5.5V CC CC CC 220nF 220nF 220nF 10H 10H 10H 0.1F 2.2F 0.1F 2.2F 0.1F 2.2F V CAP SW V V CAP SW V V CAP SW V L CC L CC L CC LTC2870 LTC2871 LTC2870, 485/232 TE485 RS485 LTC2871 RS232 RS485 TERMINATION Y DY OFF ON 120 Y Y DI Z DI, Z Z DY A 120 DZ RO RS485 B H/F FULL HALF RA DIN1 DOUT1 DUPLEX A A ROUT1 RIN1 RO, B B RA DIN2 DOUT2 RB ROUT2 RIN2 V V V V V V DD EE DD EE DD EE GND GND GND 1F 1F 1F 1F 1F 1F 28701 TA01 28701fb 1 For more information www.linear.com/LTC2870 ions pplica ions pplica ion uresLTC2870/LTC2871 (Notes 1 and 2) a Te Maxi Mu M r a T Input Supplies FEN, RA, RB, RO, ROUT1, ROUT2 ...0.3V to (V + 0.3V) L V , V ..................................................... 0.3V to 7V Differential Enabled Terminator Voltage CC L Generated Supplies (A-B or Y-Z) ..........................................................6V V ................................................ V 0.3V to 7.5V Operating Temperature DD CC V .........................................................0.3V to 7.5V LTC2870C/LTC2871C ............................... 0C to 70C EE SW ........................................... 0.3V to (V + 0.3V) LTC2870I/LTC2871I .............................40C to 85C DD CAP ............................................. 0.3V to (V 0.3V) LTC2870H .......................................... 40C to 125C EE A, B, Y, Z, RIN1, RIN2, DOUT1, DOUT2 ....15V to 15V Storage Temperature Range .................. 65C to 125C DI, DZ, DY, RXEN, DXEN, LB, H/F, TE485, RX485, Lead Temperature (Soldering, 10 sec) DX485, RX232, DX232, DIN1, DIN2, FE package........................................................300C 485/232, CH2......................................... 0.3V to 7V p in c F T LTC2870 LTC2870 TOP VIEW TOP VIEW 1 28 V LB L 2 27 V H/F CC 3 26 GND TE485 28 27 26 25 24 23 4 25 A V EE V 1 22 A EE 5 24 B RA RA 2 21 B 6 23 V RB CC RB 3 20 V CC 7 22 Y 485/232 485/232 4 29 19 Y 29 V 8 21 GND EE RXEN V RXEN 5 18 GND EE 9 20 Z DXEN DXEN 6 17 Z 10 19 V 7 16 DY DY V CC CC 11 18 V DZ 8 15 V DZ DD DD 9 10 11 12 13 14 12 17 SW FEN 13 16 GND GND 14 15 V CAP EE UFD PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN FE PACKAGE 28-LEAD PLASTIC TSSOP T = 150C, = 43C/W JMAX JA EXPOSED PAD (PIN 29) IS V , EE T = 150C, = 30C/W JMAX JA MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 29) IS V , EE MUST BE SOLDERED TO PCB 28701fb 2 For more information www.linear.com/LTC2870 FEN TE485 GND H/F CAP LB V V EE L GND V CC SW GND ion igura on ings bsolu