It supports Master/Slave operation. It runs in Free Run, Locked, or Hold-Over modes. It's available as a standalone chip. These are some of the features of the STC3800 synchronous timing source for Sonet/SDH networks. In the Free Run mode, it locks onto an oven controller crystal oscillator (OCXO). In the locked mode, it locks on one of eight input reference clocks with automatic frequence detection. Compliant with the Telcordia GR-1244-CORE, GR-253, and ITU-T G.812/G.813 standards, the chip delivers four output signals: a sync-clock up to 155.52 MHz, a Sync-8K at 8 kHz, a Sync-2K fixed at 2 kHz, and a selectable 1.544- or 2.048-MHz VBITS signal. When used with the company's OCXOs, the chip has better than a 1 part-per-billion Hold-Over accuracy. The chip supports both serial-peripheral-interface serial and 8-bit parallel bus inputs and operates from a 3.3-V supply. Housed in a 144-contact FBGA, the STC3800 is priced at $178 each in quantities of 1000 units.