The ZL30409 T1/E1 System Synchronizer contains a digital phase-locked loop (DPLL), which provides timing and synchronization signals for multitrunk T1 and E1 primary rate transmission links. The ZL30409 generates ST-BUS clock and framing signals that are phase locked to either a 19.44 MHz, 2.048MHz, 1.544MHz, or 8kHz input reference.