The DFA S1-LHZ series of high stability miniature temperature compensated crystal oscillators (TCXOs) offer up to Stratum 3 stability for SDH/SONET telecommunications systems. The 9 × 14 × 6 mm SMD package implements a temperature compensation ASIC, and offers full Stratum 3 holdover mode compliance (± 0.37 ppm/24 hours) from 0 to 70°C up to 13 MHz and from 0 to 50°C up to 20 MHz. It also features ± 4.6 ppm/15 years overall stability. Standard frequencies include 1.544, 2.048, 12.8, 19.44 MHz and 20.00 MHz, although others can be specified. The DFA S1-LHZ provides a LVHCMOS output and a tri-state option.