The DS3251 (single), DS3252 (dual), DS3253
(triple), and DS3254 (quad) line interface units (LIUs)
perform the functions necessary for interfacing at the
physical layer to DS3, E3, or STS-1 lines. Each LIU
has independent receive and transmit paths and a
built-in jitter attenuator. An on-chip clock adapter
generates all line-rate clocks from a single input
clock. Control interface options include 8-bit parallel,
SPI, and hardware mode.