SPECIFICATIONS
TYPICAL APPLICATION
FOR A PIERCE OSCILLATOR
Specifications are typical at 25
O
C unless otherwise noted.
Specifications are subject to change without notice.
Parameters
Frequency, (Hz)
Motional Resistance, R
1
(Ω)
Motional Resistance, R
1
MAX
Motional Capacitance, C
1
(fF)
Quality Factor, Q (k)
Shunt Capacitance, C
0
(pF)
Standard Calibration
Tolerance*
3.5
250
1.0
+
_
+
_
+
_
Fundamental
600 K 1.0 M
300
400
600
3KΩ
2.0
200
0.8
1.3
150
0.7
Overtone
500
1000
1.4 M 1.8432 M 2.4576 M
3.5
80
1.0
1.5
45
0.8
The CX4 family of surface mount crystals are ideal for
small, high density, battery operated portable products. The
CX4 crystal designed in a Pierce oscillator (single inverter)
circuit provides very low current consumption and high
stability. A conventional CMOS Pierce oscillator circuit is
shown below. The crystal is effectively inductive and in a PI-
network circuit with C
D
and C
G
provides the additional
phase shift necessary to sustain oscillation. The oscillation
frequency (f
0
) is 50 to 250 ppm above the crystal’s series
resonant frequency (f
S
).
Drive Level
R
A
is used to limit the crystal’s drive level by forming a
voltage divider between R
A
and C
D
. R
A
also stabilizes the
oscillator against changes in the amplifiers output
resistance (R
0
). R
A
should be increased for higher voltage
operation.
Load Capacitance
The CX4 crystal calibration tolerance is influenced by the
effective circuit capacitances, specified as the load
capacitance (C
L
). C
L
is approximately equal to:
C
L
=
C
D
x C
G
C
D
+ C
G
+
C
S
_
500 ppm (
+
0.05%)
_
1000 ppm (
+
0.1%)
_
10000 ppm (
+
1.0%)
Drive Level
3
µW
MAX
Load Capacitance, C
L
**
7pF
Turning Point, T
0
**
35
O
C
Temperature Coefficient, k
-0.035 ppm/
O
C
2
TYP
Note: Frequency f at temperature T is related to frequency f
0
at
turning point temperature T
0
by: f-f
0
2
=
k(T-T
0
)
f
0
Functional Mode
Extensional
Aging, first year
5ppm MAX
Shock, survival
1500 g peak, 0.3 ms,
1
/
2
sine
Vibration, survival
20 g RMS, 10-2,000 Hz random
Operating Temp. Range
-10
O
C to +70
O
C (Commercial)
-40
O
C to +85
O
C (Industrial)
-55
O
C to +125
O
C (Military)
Storage Temp. Range
-55
O
C to +125
O
C
(1)
NOTE: C
D
and C
G
include stray layout to ground and C
S
is the stray shunt capacitance between the crystal
terminal. In practice, the effective value of C
L
will be less
than that calculated from C
D
, C
G
and C
S
values because
of the effect of the amplifier output resistance. C
S
should
be minimized.
The oscillation frequency (f
0
) is approximately equal to:
f
0
=
f
S
1
+
Where f
S
C
1
C
0
C
1
2(C
0
+ C
L
)
Max Process Temperature
*Tighter tolerances available
**Other values available
260 C for 20 sec.
O
[
]
(2)
NOTE: All values subject to change without notice.
TERMINATIONS
= Series resonant frequency of the crystal
= Motional Capacitance
= Shunt Capacitance
Designation
SM1
SM2
SM3
Termination
Gold Plated
Solder Plated
Solder Dipped
CONVENTIONAL CMOS
PIERCE OSCILLATOR CIRCUIT
R
f
BUFFER
OSC
Freq (f
O
)
PACKAGING OPTIONS
CX4
- Tray Pack
- Tape and Reel
(Reference tape and reel data sheet 10109)
AMPLIFIER
R
A
HOW TO ORDER CX4 CRYSTALS
CX4
S
C
SM1
1.8432M
Frequency
K = kHz
M = MHz
,
500
Calibration
Tolerance
@25
O
C
(in ppm)
/
M
Operating Temp. Range:
C = -10
O
C to +70
O
C
I = -40
O
C to +85
O
C
M = -55
O
C to +125
O
C
S = Customer Specified
C
G
C = Ceramic Lid
Blank = Glass Lid
“S” if special or
custom design.
Blank if standard
CX4
XTAL
C
D
SM1 = Gold Plated
SM2 = Solder Plated
SM3 = Solder Dippe
d
10161 Rev A
S
YS
ERT
T
E
M
C
IFIC
T
A
N
IO
RSG Electronic Components GmbH - Sprendlinger Landstr. 115 - 63069 Offenbach - Germany - www.rsg-electronic.de
IS
O
90
01
RSG [ RSG ELECTRONIC COMPONENTS GMBH ]
