The LTC2870 and LTC2871 RS232/RS485 multiprotocol transceivers just introduced by Linear Technology offer switchable integrated terminations for 3.3- and 5V systems.
RS485 systems require a termination resistor on the ends of the communication bus to minimize signal reflections. Both the LTC2870 and LTC2871 integrate pin-controlled termination resistors for interface reconfiguration, eliminating external resistors and control relays. The termination resistors, when enabled, are automatically switched on or out to match the transceiver's protocol selection of RS232 or RS485.
The LTC2870 can be configured as two RS-232RS-232 single-ended transceivers or one RS-485 differential transceiver on shared I/O lines, whereas the LTC2871 offers independent control of two RS-232RS-232 transceivers and one RS-485 transceiver, each on dedicated I/O lines.
An optional 1.7 to 5.5-V logic supply enables digital interfacing, and an integrated DC/DC boost converter eliminates the need for multiple supplies to drive RS-232RS-232 levels.
The LTC2870 and LTC2871 are suitable for applications including software-selectable multiprotocol interface ports, point-of-sale terminals, security cameras, cable repeaters and protocol translators
The LTC2870 is available in 28-pin 4mm x 5mm QFN and TSSOP packages, and the LTC2871 is available in 38-pin 5mm x 7mm QFN and TSSOP packages. Prices start at $5.00 each in 1,000 piece quantities.