The TI380C60A token-ring interface device is a full-duplex electrical interface compatible with ISO/ IEC 8802.5:1995 (ANSI / IEEE Std. 802.5) token-ring access method and physical layer specifications. The TI380C60A operates at the IEEE standard 4- and 16-Mbps data rates. The Manchester-encoded data stream is received and phase-aligned using an on-chip phase-locked loop ( PLL). Both the recovered clock and data are passed to the protocol-handling circuits of one of the TI380C2x single-chip token-ring commprocessors for serial-to-parallel conversion and data processing. On transmit, the TI380C60A buffers the output of the TI380C2x and drives the media by way of suitable isolation and waveform-shaping components. All necessary functions required to interface with an IEEE-802.5 token ring are provided. These include the PLL, the phantom drive (to control the relays within a trunk-coupling unit), and wire-fault detection circuits. An internal wrap function is provided for self-test, and a watchdog timer is included to provide fail-safe deinsertion from the ring in the event of a station microcode or commprocessor failure. The TI380C60A, when coupled with one of the TI380C2x token-ring commprocessors, forms a highly integrated token-ring LAN adapter compatible with the ISO / IEEE Standard 802.5. The TI380C60A synthesizes the necessary token-ring reference clock for its own use and for the TI380C2x. This removes the need for external components to provide this function.