Zarlink approved TCXO for GR-1244 & GR-253 Stratum 3 applications. Frequency Parameters Frequency Frequency Stability Ageing 20.0MHz ±0.28ppm ±4.6ppm max after 20 years Electrical Parameters Supply Voltage 3.3V ±5% Operating Temperature Ranges -20 to 70°C Output Details Output Compatability Dr.