TYPICAL APPLICATION
FOR A PIERCE OSCILLATOR
SPECIFICATIONS
Specifications are typical at 25OC unless otherwise noted.
Specifications are subject to change without notice.
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 CD and CG provides the additional
phase shift necessary to sustain oscillation. The oscillation
frequency (f0) is 50 to 250 ppm above the crystal’s series
resonant frequency (fS).
Parameters
Frequency, (Hz)
Fundamental
Overtone
600 K 1.0 M 1.4 M 1.8432 M 2.4576 M
Motional Resistance, R1 (Ω)
Motional Resistance, R1 MAX
300
400
600
3KΩ
500
1000
Motional Capacitance, C1 (fF) 3.5
2.0
200
0.8
1.3
150
0.7
3.5
80
1.5
45
Quality Factor, Q (k)
Shunt Capacitance, C0 (pF)
Standard Calibration
Tolerance*
250
1.0
1.0
0.8
Drive Level
+_ 500 ppm ( +_ 0.05%)
+_ 1000 ppm ( +_ 0.1%)
+_ 10000 ppm ( +_ 1.0%)
RA is used to limit the crystal’s drive level by forming a
voltage divider between RA and CD. RA also stabilizes the
oscillator against changes in the amplifiers output
resistance (R0). RA should be increased for higher voltage
operation.
Drive Level
3 µW MAX
Load Capacitance, CL**
Turning Point, T0**
Temperature Coefficient, k
7pF
Load Capacitance
35OC
The CX4 crystal calibration tolerance is influenced by the
effective circuit capacitances, specified as the load
capacitance (CL). CL is approximately equal to:
-0.035 ppm/OC2 TYP
Note: Frequency f at temperature T is related to frequency f0 at
turning point temperature T0 by:
2
f-f0
f0
CD x CG
=
k(T-T )
0
=
+
(1)
CL
CS
CD + CG
Functional Mode
Aging, first year
Extensional
5ppm MAX
NOTE: CD and CG include stray layout to ground and CS
is the stray shunt capacitance between the crystal
terminal. In practice, the effective value of CL will be less
than that calculated from CD, CG and CS values because
of the effect of the amplifier output resistance. CS should
be minimized.
Shock, survival
Vibration, survival
Operating Temp. Range
1500 g peak, 0.3 ms, 1/2 sine
20 g RMS, 10-2,000 Hz random
-10OC to +70OC (Commercial)
-40OC to +85OC (Industrial)
-55OC to +125OC (Military)
-55OC to +125OC
The oscillation frequency (f0) is approximately equal to:
C1
Storage Temp. Range
=
+
(2)
f0 fS
1
[
260OC for 20 sec.
]
Max Process Temperature
2(C0 + CL)
*Tighter tolerances available
**Other values available
Where
= Series resonant frequency of the crystal
= Motional Capacitance
= Shunt Capacitance
fS
C1
C0
NOTE: All values subject to change without notice.
TERMINATIONS
CONVENTIONAL CMOS
PIERCE OSCILLATOR CIRCUIT
Designation Termination
SM1
SM2
SM3
Gold Plated
Solder Plated
Solder Dipped
Rf
BUFFER
PACKAGING OPTIONS
CX4 - Tray Pack
OSC
Freq (fO )
RA
AMPLIFIER
- Tape and Reel
(Reference tape and reel data sheet 10109)
HOW TO ORDER CX4 CRYSTALS
CX4
S
C
SM1
1.8432M
,
500
/
M
CG
CD
CX4
XTAL
Frequency
K = kHz
M = MHz
Calibration
Tolerance
@25OC
Operating Temp. Range:
C
I
= -10OC to +70OC
= -40OC to +85OC
C = Ceramic Lid
Blank = Glass Lid
(in ppm)
M = -55OC to +125OC
“S” if special or
custom design.
Blank if standard
SM1 = Gold Plated
SM2 = Solder Plated
SM3 = Solder Dippe
S
= Customer Specified
d
10161 Rev A
E
STATEK CORPORATION 512 N. MAIN ST., ORANGE, CA 92868 714-639-7810 FAX: 714-997-1256 www.statek.com
STATEK [ STATEK CORPORATION ]
