The DS3105 is a low-cost, feature-rich timing IC for telecom line cards. Typically the device accepts two reference clocks from dual redundant system timing cards. The DS3105 continually monitors both inputs and performs automatic hitless reference switching if the primary reference fails. The highly programmable DS3105 supports numerous input and output frequencies including frequencies required for SONET/SDH, Synchronous Ethernet (1G, 10G and 100Mb/s), wireless basestations and CMTS systems. PLL bandwidths from 18 Hz to 400 Hz are supported, and a wide variety of PLL characteristics and device features can be configured to meet the needs of many different applications.