Crystal Units FAQ

Characteristics

If small oscillation amplitude will be a cause of trouble in oscillation circuit?

A. If oscillation amplitude is excessively small, it might be cause of malfunction on module.

Please refer how to measure oscillation amplitude below.
How to check oscillation waveform

If you need to confirm how large amplitude is required for IC, please check it by below.

  • Contact IC manufacturer to confirm which side is connected to next portion of clock system in the IC, input or output side.
  • Utilize signal generator instead of crystal unit to check function of IC and module by changing signal amplitude.

Measure 1: To change damping resistance small
  To change damping resistance small, oscillation margin becomes high due to less attenuation of amplitude.
After you change damping resistance small, please check actual drive level of crystal unit is within the spec, because drive level will be large due to small damping resistance.
Measure 2: To change external load capacitance small
  To change external load capacitance small, oscillation amplitude becomes large.
Please pay attention that excessively small capacitance will cause of small amplitude.
Please also check actual oscillation frequency because it will be high due to small load capacitance.
Measure 3: To change external load capacitance at input side of inverter small
  Oscillation amplitude at input side of inverter becomes large due to high impedance.
As same as measure 2, please pay attention to excessive small capacitance and frequency shift.

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