TYPICAL APPLICATION
FOR A PIERCE OSCILLATOR
SPECIFICATIONS
Specifications are typical at 25OC unless otherwise noted.
Specifications are subject to change without notice.
The low profile CX miniature surface mount crystal is ideal
for small, high density, battery operated portable products.
The CX 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 15 to 150 ppm above the
crystal’s series resonant frequency (fS).
Frequency Range
Functional Mode
Calibration Tolerance*
760 kHz - 1.35 MHz
Extensional
+_ 500 ppm (0.05%)
+_ 1000 ppm (0.1%)
+_ 10000 ppm (1.0%)
7 pF
Load Capacitance
Motional Resistance (R1)
5 kΩ MAX
Drive Level
Motional Capacitance (C1) 1.2fF
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.
Quality Factor (Q)
Shunt Capacitance (C0)
Drive Level
150 k
1.0 pF
W MAX
35OC
3
µ
Turning Point (T )**
0
Temperature Coefficient (k) -0.035 ppm/OC2
Load Capacitance
Aging, first year
Shock, survival
Vibration, survival
Operating Temp. Range
5 ppm MAX
1000 g peak, 0.3 ms,1/2 sine
10 g RMS, 20-1,000 Hz random
-10OC to +70OC (Commercial)
-40OC to +85OC (Industrial)
-55OC to +125OC (Military)
-55OC to +125OC
The CX crystal calibration tolerance is influenced by the
effective circuit capacitances, specified as the load
capacitance (CL). CL is approximately equal to:
CD x CG
=
+
(1)
CL
CS
CD + CG
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.
Storage Temp. Range
Max Process Temperature 260OC for 20 sec.
Note: Frequency f at temperature T is related to frequency f0
at turning point temperature T0 by:
2
f-f0
f0
=
k(T-T )
0
The oscillation frequency (f0) is approximately equal to:
* Tighter frequency calibration available.
** Other turning points available.
C1
=
+
(2)
f0 fS
1
[
]
2(C0 + CL)
TERMINATIONS
Where
= Series resonant frequency of the crystal
= Motional Capacitance
= Shunt Capacitance
fS
C1
C0
Designation
SM1
SM2
Termination
Gold Plated
Solder Plated
Solder Dipped
CONVENTIONAL CMOS
PIERCE OSCILLATOR CIRCUIT
SM3
PACKAGING OPTIONS
Rf
CX2SM - Tray Pack
-16mm tape, 7” or 13” reels
(Reference tape and reel data sheet 10109)
BUFFER
OSC
Freq (fO)
RA
AMPLIFIER
CX2
HOW TO ORDER CX2SM CRYSTALS
CX2
S
C
SM1
1.0M,
500
/
M
Frequency
K = kHz
M = MHz
Blank = Glass Lid
C = Ceramic Lid
Operating Temp. Range:
C
I
= -10OC to +70OC
= -40OC to +85OC
CG
CD
Calibration
Tolerance
@ 25OC
SM1 = Gold Plated
SM2 = Solder Plated
SM3 = Solder Dipped
M = -55OC to +125OC
“S” if special or
custom design.
Blank if Std.
S
= Customer Specified
(in ppm)
10135 - Rev B
E
STATEK CORPORATION 512 N. MAIN ST., ORANGE, CA 92868 714-639-7810 FAX: 714-997-1256 www.statek.com
STATEK [ STATEK CORPORATION ]
