Description
The MT8977 is a variant of the MT8976 framer, which has been enhanced to meet ACCUNET® T1.5 wander tolerance (138 UI).
The MT8977 meets ESF and D3/D4 formats, and is compatible with SLC-96 systems.

Features
• D3/D4 or ESF framing and SLC-96 compatible
• Two frame elastic buffer with jitter tolerance improved to 156 UI
• Insertion and detection of A, B, C, D bits, signalling freeze, optional debounce
• Selectable B8ZS, jammed bit (ZCS) or no zero code suppression
• Yellow alarm and blue alarm signal capabilities
• Bipolar violation count, FT error count, CRC error count
• Selectable robbed bit signalling
• Frame and superframe sync. signals, Tx and Rx
• AMI encoding and decoding
• Per channel, overall, and remote loop around
• Digital phase detector between T1 line and ST-BUS
• One uncommitted scan point and drive point
• Pin compatible with MT8976 and MT8979
• ST-BUS compatible

Applications
• DS1/ESF digital trunk interfaces
• Computer to PBX interfaces (DMI and CPI)
• High speed computer to computer data links