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 250 ppm above the crystal’s series
resonant frequency (fS).
Parameters
Fundamental
Overtone
Frequency Range, (Hz)
Motional Resistance,R1(Ω)
555 k 614 k 1.0 M 1.4 M1.8432 M 2.1M
600 275 500 775
3 k
300
475
Motional Resistance,R1 MAX
Ω
Motional Capacitance,C1 (fF) 2.5 3.6 2.0 1.5
2.8
2.6
Quality Factor, Q (k)
170 260 190 100
110
1.3
70
Shunt Capacitance,C0 (pF)
Calibration Tolerance*
1.2 1.3 1.1 1.0
1.3
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**
7 pF
Load Capacitance
Turning Point (T )**
35OC
The CX crystal calibration tolerance is influenced by the
effective circuit capacitances, specified as the load
capacitance (CL). CL is approximately equal to:
0
Temperature Coefficient (k) -0.035 ppm/OC2
Note: Frequency f at temperature T is related to frequency f0
2
at turning point temperature T by:
f-f0
f0
0
CD x CG
=
k(T-T )
0
=
+
(1)
CL
CS
CD + CG
Function Mode
Aging, first year
Shock, survival
Extensional
5 ppm 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.
750 g peak, 0.3 ms, 1/2 sine
Vibration, survival
Operating Temp. Range
10 g RMS, 20-1,000 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:
Storage Temp. Range
C1
Max Process Temperature 260OC for 20 sec.
=
+
(2)
f0 fS
1
[
]
2(C0 + CL)
*Tighter tolerances available.
** Other values available.
Where
= Series resonant frequency of the crystal
= Motional Capacitance
= Shunt Capacitance
fS
C1
C0
TERMINATIONS
Designation
SM1
SM2
Termination
CONVENTIONAL CMOS
PIERCE OSCILLATOR CIRCUIT
Gold Plated
Solder Plated
Solder Dipped
SM3
Rf
PACKAGING OPTIONS
BUFFER
CX1SM - Tray Pack
- Tape and Reel
(Reference tape and reel data sheet 10109)
OSC
Freq (fO)
RA
AMPLIFIER
HOW TO ORDER CX1SM CRYSTALS
CX1
S
C
SM1
1.0M,
500 / M
Frequency
K = kHz
M = MHz
Operating Temp. Range:
Blank = Glass Lid
C = Ceramic Lid
C
I
= -10OC to +70OC
= -40OC to +85OC
CG
CD
CX1
M = -55OC to +125OC
SM1 = Gold Plated
SM2 = Solder Plated
SM3 = Solder Dipped
Calibration
“S” if special or
custom design.
Blank if Std.
XTAL
S
= Customer Specified
Tolerance
@ 25OC
(in ppm)
10129 - Rev B
E
RSG Electronic Components GmbH - Sprendlinger Landstr. 115 - 63069 Offenbach - Germany - www.rsg-electronic.de
RSG [ RSG ELECTRONIC COMPONENTS GMBH ]
