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The F81439 is programmable, monolithic multi-protocol transceiver device that contains RS-232 and RS-485 / RS-422 drivers and receivers. The F81439 can be reconfigured into eight operating modes including one pure RS-232 (3TX/5RX), one RS-485 (1TX/1RX) driver (TX) half duplex mode, one RS-485 (1TX/1RX) receiver (RX) half duplex mode, RS-422 (1TX/1RX) full duplex mode, RS-485 (1TX/1RX) driver (TX) half duplex mode with built-in termination resistor, RS-422 (1TX/1RX) full duplex mode with built-in termination resistor, coexist RS-232 (TX/RX only) with RS-485 mode without the need for the bus switch IC and a shutdown mode which can be selected whenever you need by changing the logic state of the 3 mode selection pins. The extra charge pumps deliver true RS-232 driver output voltage from a single power supply at either 3.3V ~ 5V. The F81439 requires only four 0.1uF capacitors for the charge pump. This item converts the 5 V input power to the ±10 V (norminal) required for RS-232 output levels. The F81439 meets the EIA-232-E V0.28 specification while using a single digital 3.3V or 5 V supply and particularly suites for those applications where ±12V is not available. A slew rate control pin configures driver outputs for either high data rate or slew-controlled data rates. Slew-controlled outputs minimize the problems that caused by the reflections and ringing on long or un-terminated cables. The RS-422/RS-485 receiver and transceiver feature high impedance which allow up to 256 transceivers on a shared bus. When configured in RS-485/RS-422 mode, the driver may be individually enabled into tri-state, simplifying use on shared buses or bidirectional 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 has a 5KΩ pull-down to ground. Differential Receivers will default to output logic 1 if inputs are floating, shorted or open but terminated. |