The SN75LBC776 is a low-power LinBiCMOS device that incorporates the drivers and receivers for a 9-pin GeoPort host interface. GeoPort combines hybrid EIA/TIA-422-B and EIA/TIA-423-B drivers and receivers to transmit data up to four megabits per second (Mbit/s) full duplex. GeoPort is a serial communications standard that is intended to replace the RS-232, Appletalk, and LocalTalk printer ports all in one connector in addition to providing real-time data transfer capability. It provides point-to-point connections between GeoPort-compatible devices with data transmission rates up to 4 Mbit/s full duplex and a hot-plug feature. Applications include connection to telephony, integrated services digital network (ISDN), digital sound and imaging, fax-data modems, and other serial and parallel connections. The GeoPort is backwardly compatible to both LocalTalk and AppleTalk.
While the SN75LBC776 is powered-off (VCC = 0) the outputs are in a high-impedance state. When the shutdown (SHDN) terminal is high, the charge pump is powered down and the outputs are in a high-impedance state. The driver enable (DEN)\ terminal sends the outputs of the differential driver into a high-impedance state with a high input signal. All drivers and receivers have fail-safe mechanisms to ensure a high output state when the inputs are left open.
A switched-capacitor voltage converter generates the negative voltage required from a single 5-V supply using four 0.1-uF capacitors, two capacitors between the C+ and C- terminals and two capacitors between VEE and ground.
The SN75LBC776 is characterized for operation over the 0°C to 70°C temperature range.