Linear Technology Corp.’s LTC2859 and LTC2861 are half-duplex and full-duplex RS485 transceivers with switchable, integrated termination. Traditional RS485 networks require 120-Ohm termination resistors to be installed by the end user based on the physical layout of the twisted-pair wires and the placement of the nodes. As the bus is extended, the termination must be changed again by the end user.

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Switching the integrated termination in the LTC2859/LTC2861 on or off under software control allows the proper nodes to be terminated without the end user's physical intervention. In addition to the innovative termination capacity, the LTC2859/LTC2861 offer advanced transceiver features for industrial, medical and automotive applications. A slew rate control pin allows data rates up to 20 Mbps or a low-EMI mode at 250 kbps. The bus pin protection exceeds ±15 kV for ESD strikes (human body model). The receiver input impedance allows up to 256 nodes on a single bus. These features provide more functionality than existing RS485 transceivers and the integrated termination combined with the tiny DFN package provide a smaller solution overall.

Specified over the commercial and industrial temperature ranges, the LTC2859 is offered in the 10-lead (3 mm x 3 mm) DFN package and the LTC2861 is offered in the 12-lead (4 mm x 3 mm) DFN and 16-lead SSOP packages. Pricing begins at $1.55 each in 1000-piece quantities.