Handling Notes
For Proper Use of Crystal Units
1. Characteristics of crystal units
The thickness of crystal vibrator of the AT cut crystal unit as described in the previous page differs depending on the
overtone mode.
(1) Relationship between thickness of crystal blank and oscillation frequency
Cut angle/mode
overtone
Frequency range
(MHz)
Formula of thickness
of crystal blank
AT/Fundamental mode
AT/3’rd O. T
3.5 to 33
33 to 100
100 to 150
150 to 200
1.67/f
5.01/f
AT/5’th O. T
8.35/f
AT/7’th O. T
11.69/f
f : Series resonance frequency (MHz)
In case of calculating the thickness of AT-cut 16MHz
t=1.67/16=0.104(mm)
(2) Examples of specifications for frequency-temperature characteristics
The frequency-temperature characteristics of the AT cut crystal unit are tertiary curves.
The diagram below shows examples of the tertiary curves that pass temperature range and frequency deviation specifications.
The range enclosed by the smaller rectangular satisfies the following specification:
±1010-6 (-10 to 60: 25°C)
The range enclosed by the larger rectangular satisfies the following specification:
±5010-6 (-20 to 70: 25°C)
Temperature (°C)
Ð70
Ð50
Ð30
Ð10
10
30
50
70
90
110
70
60
50
40
30
20
10
0
Ð10
Ð20
Ð30
Ð40
Ð50
Ð60
Ð70
* These are examples. Required frequency-temperature specifications are determined through
individual consultations.
(3) Equivalent electric circuit and equivalent constant of crystal unit
The following equivalent constants are used near the resonance frequency.
L1 : Motional inductance in the equivalent electric circuit
L1
C1
C0
R1
C1 : Motional capacitance in the equivalent electric circuit
R : Motional resistance in the equivalent electric circuit
C0 : Parallel capacitance in the equivalent electric circuit
Equivalent electric circuit of a quarts crystal unit
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KYOCERA AVX [ KYOCERA AVX ]
