Linear公司的LTC2870/LTC2871是多模式RS232/RS485收发器，支持RS232，RS485和RS422协议，工作电压3V-5.5V. LTC2870可配置成两个单端RS232收发器重或一个差分RS485，而LTC2871提供两个RS232收发器和一个RS485收发器的独立控制.主要用在灵活的RS232/RS485/RS422接口，软件选择的多协议接口端，POS终端，电缆中继器和协议转换器.本文介绍了LTC2870/LTC2871主要特性，方框图以及各种通信配置框图.

 LTC2870/71:RS232/RS485 Multiprotocol Transceivers with Integrated Termination

 The LTC2870/LTC2871 are robust pin-configurable multiprotocol transceivers， supporting RS232， RS485， and RS422 protocols， operating on a single 3V to 5.5V supply. The LTC2870 can be configured as two RS232 single-ended transceivers or one RS485 differential transceiver on shared I/O lines. The LTC2871 offers independent control of two RS232 transceivers and one RS485 transceiver， each on dedicated 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 fordiagnostic 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 inductor and one capacitor， eliminating the need for multiple supplies for driving RS232 levels

 LTC2870/LTC2871主要特性:

One RS485 and Two RS232 Transceivers

3V to 5.5V Supply Voltage

20Mbps RS485 and 500kbps RS232

Automatic Selection of Integrated RS485 (120Ω) and RS232 (5kΩ)Termination Resistors

Half-/Full-Duplex RS485 Switching

High ESD: ±26kV (LTC2870)， ±16kV (LTC2871)

Logic Loopback Mode

1.7V to 5.5V Logic Interface

Supports Up to 256 RS485 Nodes

RS485 Receiver Failsafe Eliminates UART Lockup

Available in 28-Pin 4mm 5mm QFN and

TSSOP (LTC2870)， and 38-Pin 5mmx7mm QFN and TSSOP (LTC2871)

LTC2870/LTC2871应用:

Flexible RS232/RS485/RS422 Interface

Software Selectable Multiprotocol Interface Ports

Point-of-Sale Terminals

Cable Repeaters

Protocol Translators