Single-Bus RS485/RS232 Multiprotocol Transceiver with Switchable Termination

The LTC2873 is a robust pin-configurable multiprotocol transceiver that supports RS232, RS485, and RS422 protocols while operating on a single 3V to 5.5V supply. The LTC2873 can be configured as a half-duplex RS485 transceiver or as an RS232 transceiver using the same two bus pins.

A pin-controlled integrated termination resistor allows for easy interface reconfiguration, eliminating external resistors and control relays. Loopback mode steers the driver inputs to the receiver outputs for diagnostic self-test. The RS485 receiver supports up to 256 nodes per bus, and features full failsafe operation for floating, shorted or terminated inputs.

An integrated DC/DC boost converter uses a tiny 2mm × 1.6mm inductor and one capacitor, eliminating the need for multiple supplies when driving RS232 levels.

Applications

* Software Selectable RS232/RS485/RS422 Interface

* Industrial Sensors and Actuators

* Alarm Systems

* Traffic Control and Monitoring

* Highway Signs and Jumbo Displays

* One RS485 or One RS232 Transceiver

* 3V to 5.5V Supply Voltage

* Up to 20Mbps RS485

* Slew-Controlled RS232 Operation:

* Selectable 1Mbps or 250kbps

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

* High ESD: ±26kV HBM

* Logic Loopback Mode

* 1.7V to 5.5V Logic Interface

* Supports Up to 256 RS485 Nodes

* RS485 Receiver Failsafe Eliminates UART Lockup

* H-Grade Available (–40°C to 125°C)

* Available in 24-Pin 4mm × 5mm QFN Package