The F81438 is programmable, monolithicmulti-protocol transceiver devicethatcontainsRS-232andRS-485/RS-422 driversandreceivers.TheF81438 can be reconfigured into four operating modesincluding RS-232 only (3TX/5RX), one RS-485 (1TX/1RX)  driver (TX) halfduplex mode, one RS-485 (1TX/1RX) receiver (RX) halfduplex mode, and RS-422 (1TX/1RX) fullduplex mode which can be selected whenever you need by changing the logic state of the 2 mode selection pins.The device can implement a dual-modeserial port, mixed mode ports or as an interface signal translator. The extra charge pumps deliver true RS-232 driver output voltage from a single power supply at 5V. A slew rate control pinconfiguresdriveroutputsforeither highdatarateorslew-controlleddatarates.  Slew-controlled outputs minimize the problems that caused by the reflections and ringing on long or un-terminated cables.  

All RS-485 receivers or transceivers feature high impedance which allow up to 256 transceivers on a shared bus. WhenconfiguredinRS-485/RS-422mode,each driver may be individually enabled or put into tri-state, simplifyinguseonsharedbusesorbidirectional communication. All receivers have advanced failsafe protection to prevent oscillation when inputs are un– connected by defaulting to logic high output level. No external biasing resistors are required. In RS-232 mode each receiver input hasa 5kΩ pull-down to ground. Differential Receivers willdefaulttooutputlogic1ifinputsarefloating, shorted or open but terminated. All driver outputs and receiver inputs are protected against ESD strikes up to ±15Kvolts(IEC 61000-4-2 Air Gap).