LTC2873 Single-Bus RS485/RS232 Multiprotocol Transceiver with Switchable Termination FEATURES DESCRIPTION n One RS485 or One RS232 Transceiver The LTC 2873 is a robust pin-configurable multiprotocol n 3V to 5.5V Supply Voltage transceiver that supports RS232, RS485, and RS422 n Up to 20Mbps RS485 protocols while operating on a single 3V to 5.5V supply. n Slew-Controlled RS232 Operation: The LTC2873 can be configured as a half-duplex RS485 n Selectable 1Mbps or 250kbps transceiver or as an RS232 transceiver using the same n Automatic Selection of Integrated RS485 (120) two bus pins. and RS232 (5k) Termination Resistors A pin-controlled integrated termination resistor allows for n High ESD: 26kV HBM easy interface reconfiguration, eliminating external resis- n Logic Loopback Mode tors and control relays. Loopback mode steers the driver n 1.7V to 5.5V Logic Interface inputs to the receiver outputs for diagnostic self-test. n Supports Up to 256 RS485 Nodes The RS485 receiver supports up to 256 nodes per bus, n RS485 Receiver Failsafe Eliminates UART Lockup and features full failsafe operation for floating, shorted or n H-Grade Available (40C to 125C) terminated inputs. n Available in 24-Pin 4mm 5mm QFN Package An integrated DC/DC boost converter uses a tiny 2mm1.6mm inductor and one capacitor, eliminating APPLICATIONS the need for multiple supplies when driving RS232 levels. n All registered trademarks and trademarks are the property of their respective owners. Software Selectable RS232/RS485/RS422 Interface n Industrial Sensors and Actuators n Alarm Systems n Traffic Control and Monitoring n Highway Signs and Jumbo Displays TYPICAL APPLICATION 220nF 10H 1.7V TO V 3V TO 5.5V CC 2.2F 1F RS485/RS232 Mode Switching LTC2873 V CAP SW V L CC RS485 RS232 RS485 SHDN (485/232 (485/232 DI HIGH) LOW) DI DATA IN A/DO 485/232 RS232 RS485 5V/DIV B/RI 120 RO DATA OUT B/RI 485/232 485/232 V DD 1F A/DO RE485 RS232 D/R 3V/DIV TE485 (485) 5k DE485/ V EE F232 1F LB 2873 TA01b GND 1s/DIV 2873 TA01 REV B 1 Document Feedback For more information www.analog.comLTC2873 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Notes 1 and 2) TOP VIEW Input Supplies V , V .................................................... 0.3V to 7V CC L Generated Supplies 24 23 22 21 20 V ................................................ V 0.3V to 7.5V V 1 19 NC DD CC EE RO 2 18 V .........................................................7.5V to 0.3V V CC EE 485/232 3 17 A/DO SW ............................................... 0.3V to (V + 0.3V) DD 25 RE485 4 16 GND CAP ................................................. (V 0.3V) to 0.3V V EE EE DE485/F232 5 15 B/RI A/DO, B/RI ...................................................15V to 15V DI 6 14 V CC DI, 485/232, DE485/F232, RE485, SHDN 7 13 V DD 8 9 10 11 12 TE485, LB ................................................ 0.3V to 7V SHDN, RO .......................................0.3V to (V + 0.3V) L Differential Terminator Voltage (Enabled) UFD PACKAGE (A/DO to B/RI) ..................................................... 6V 24-LEAD (4mm 5mm) PLASTIC QFN Differential Terminator Voltage (Disabled) T = 150C, = 43C/W JMAX JA (A/DO to B/RI) ................................................... 30V EXPOSED PAD (PIN 25) IS V , MUST BE SOLDERED TO PCB EE Operating Temperature LTC2873C ............................................... 0C to 70C LTC2873I .............................................40C to 85C LTC2873H .......................................... 40C to 125C Storage Temperature Range .................. 65C to 150C ORDER INFORMATION