Crystal Oscillator


Regard To OSC Logic Level Of OSC

Terminologies
  • Nominal frequency
    The center or nominal output frequency of OSC
  • Frequency vs. Power Supply Variation
    It’s the maximum variation of output frequency within OSC supply voltage changing range. Generally, voltage changing range is ±5% or ±10%.

  • Supply current
    It’s electronic current consumption from Vcc to OSC. The supply current has different ICC at different load, typical the supply current is measured without load.
  • Frequency stability
    The maximum allowed frequency deviation between the room temperature(25°C) and other specified temperature range.
  • Operating temperature
    A specified temperature range within which output frequency and other electrical characteristics must be meet the specifications demanded.
  • Output High voltage(VOH)
    The maximum voltage at an output of the oscillator under proper loading.
  • Output Low voltage (VOL)
    The minimum voltage at an output of the oscillator under proper loading.
  • Rise Time(Tr)
    The waveform rise time from Low to High transition, measured at the specified level  10% to 90%Vcc or 20% to 80%Vcc for HCMOS/LVCMOS.
  • Fall Time(Tf)
    The waveform fall time from High to Low transition, measured at the specified level 10% to 90%Vcc or 20% to 80%Vcc for HCMOS/LVCMOS.
  • Duty Cycle
    Duty cycle is defined as the ratio of positive pulse width to the period. Duty Cycle is the closer to 50% the better.
  • Tri-state or Enable/disable function
    The OSC connected to Vcc voltage for control output. When Tri-state Pin input is left OPEN or logic is “1” ,the output is normal oscillation. When Tri-state Pin input Ground (logic is “0”), the output is high impedance state.
  • Jitter
    In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal. For high speed broadband Internet application, jitter is the smaller the better. If jitter is too big, transmission signal error occurs or an interrupt transmission, that is CDR (Clock Data Recovery) problem.