C =
Cx C
C+ C
2
1
LS
C
+
Typical application for Pierce oscillator
The low-profile CX miniature leaded crystal is ideal for small,
high density, battery operated portable products. A CX crystal
incorporated into a Pierce oscillator (single inverter) circuit
provides a high stability with low current consumption. A
conventional HCMOS Pierce oscillator circuit is shown below. The
crystal is effectively inductive and in a Pi-network circuit with C
and C providing the additional phase shift necessary to sustain
oscillation. The oscillation frequency (f ) is 15 to 150ppm above
the crystals series resonant frequency (f ).
R is used to limit the crystals drive level by forming a voltage
divider between R and C . R also stabilizes the oscillator against
changes in the amplifiers output resistance (R ). R should be
increased for higher voltage operation.
The CX crystal calibration tolerance is influenced by the effective
circuit capacitances, specified as the load capacitance (C ).
C is approximately equal to:
1
2
0
S
A
A1
A
0A
L
Drive Level
Load Capacitance
Order Code
CX-1
“S” if special
or custom design
Blank if standard
Frequency
Side leads
Calibration
Tolerance*
@ 25°C
(A)
(B)
(C)
1.0MHz
-03
*For other
calibrations
insert value
in ppm
CX-1-03
530kHz to 2.1MHz
MINIATURE QUARTZ CRYSTAL
FOR PARALLEL OSCILLATORS
CX-1-03
530kHz to 2.1MHz
MINIATURE QUARTZ CRYSTAL
FOR PARALLEL OSCILLATORS
Typical Application
NOTE: C and C include stray layout capacitance to ground. C is
the stray shunt capacitance between the crystal terminals. In
practice, the effective valus of C will be less than that calculated
from C , C , and CS values due to the effect of the amplifier output
resistance. C should be minimized.
The oscillation frequency (f ) is approximately equal to:
12
S
L
12
S
0
Where F = Series resonant frequency of the crystal
C = Motional Capacitance
C = Shunt Capacitance
S
1
0
f =
C1
0 fS
2(C+ C)
0L
1+
Conventional HCMOS Pierce Oscillator Circuit
CX-1
Buffer
Amplifier
Osc.
Freq. (Fo)
C
C
C5
RB
R)
CX-1-03 - Tray Pack (Standard)
Packaging
Temperature
Range:
C = Commercial
I = Industrial
M = Military
S = Specify
(A/I)
Blank = Glass Lid
C = Ceramic Lid
+44(0)1460 230000
+44(0)1460 230001
sales@euroquartz.co.uk
www.euroquartz.co.uk
Telephone:
Fax:
Email:
Web:
EUROQUARTZ
CX MINIATURE CRYSTALS
Page
2of2