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 150 ppm above the crystal’s series
resonant frequency (fS).
Parameters
Fundamental
32.768 100
Overtone
200
Frequency, (kHz)
Motional Resistance R1(kΩ)
Motional Capacitance C1 (fF)
Quality Factor Q (k)
50
2.3
40
18
1.07
85
2.4
2.2
140
Shunt Capacitance C0 (pF)
1.1
0.7
1.2
Load Capacitance (pF)*
Turning Point (oC)*
9
8
5
Drive Level
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.
25
10
29
Standard Calibration Tolerance**
Glass Lid:
+_ 30 ppm
(0.003%)
+
+_ 100 ppm
(0.01%)
+_ 1000 ppm _ 10000 ppm
(0.1%)
+_ 1000 ppm
(0.1%)
Load Capacitance
+
Ceramic Lid: _ 100 ppm
(0.01%)
The CX4 crystal calibration tolerance is influenced by the
effective circuit capacitances, specified as the load
capacitance (CL). CL is approximately equal to:
(1.0%)
Drive Level
0.5
µ
W MAX
Temperature Coefficient (k) -0.035 ppm/OC2
CD x CG
=
+
(1)
CL
CS
Note: Frequency f at temperature T is related to frequency f0 at
CD + CG
turning point temperature T0 by:
2
f-f0
=
k(T-T )
0
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.
f0
5 ppm
Aging, first year
Shock, survival
5,000 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)
Vibration, survival
Operating Temp. Range
The oscillation frequency (f0) is approximately equal to:
C1
=
+
(2)
f0 fS
1
[
]
2(C0 + CL)
Storage Temp. Range
-55OC to +125OC
Max Process Temperature 260OC for 20 sec.
Where
= Series resonant frequency of the crystal
= Motional Capacitance
= Shunt Capacitance
fS
C1
C0
* Other values available
** Tighter tolerances available
TERMINATIONS
CONVENTIONAL CMOS
PIERCE OSCILLATOR CIRCUIT
Designation Termination
Rf
SM1
SM2
SM3
Gold Plated
Solder Plated
Solder Dipped
BUFFER
PACKAGING OPTIONS
OSC
Freq (fO )
CX4VSM - Tray Pack
RA
AMPLIFIER
- 16mm tape, 7” or 13” reels
(Reference tape and reel data sheet 10109)
HOW TO ORDER CX4VSM CRYSTALS
CG
CD
CX4V
S
C
SM1
32.768K , 100
/
I
CX4
XTAL
Frequency
K = kHz
C = Ceramic Lid
Blank = Glass Lid
Calibration Operating Temp. Range:
Tolerance
C
= -10OC to +70OC
@25OC
I = -40OC to +85OC
“S” if special or
custom design.
Blank if standard
SM1 = Gold Plated
SM2 = Solder Plated
SM3 = Solder Dipped
(in ppm)
M = -55OC to +125OC
S
= Customer Specified
10103 - Rev C
E
RSG Electronic Components GmbH - Sprendlinger Landstr. 115 - 63069 Offenbach - Germany - www.rsg-electronic.de
RSG [ RSG ELECTRONIC COMPONENTS GMBH ]
