mc145201dt Freescale Semiconductor, Inc, mc145201dt Datasheet - Page 17

• Manufacturer Part Number: mc145201dt
• Description: 2.0 Ghz Pll Frequency Synthesizers
• Manufacturer: Freescale Semiconductor, Inc

crystal, R e , in Figure 21. The maximum drive level specified
by the crystal manufacturer represents the maximum stress
that the crystal can withstand without damage or excessive
shift in operating frequency. R1 in Figure 19 limits the drive
level. The use of R1 is not necessary in most cases.
cause the crystal to be overdriven, monitor the output
frequency (f R ) at OUTPUT A as a function of supply voltage.
(REF out is not used because loading impacts the oscillator.)
The frequency should increase very slightly as the dc supply
voltage is increased. An overdriven crystal decreases in fre-
quency or becomes unstable with an increase in supply volt-
age. The operating supply voltage must be reduced or R1
must be increased in value if the overdriven condition exists.
The user should note that the oscillator start–up time is pro-
portional to the value of R1.
CMOS inverters, many crystal manufacturers have devel-
oped expertise in CMOS oscillator design with crystals. Dis-
cussions with such manufacturers can prove very helpful
(see Table 4).
RECOMMENDED READING
Method of Measurement”, Proc. IEEE, Vol. 57, No. 2, Feb.
1969.
Control”, Electro–Technology , June 1969.
Design , May 1966.
March 7, 1985.
Machine Design , April 25, 1985.
MOTOROLA
Power is dissipated in the effective series resistance of the
To verify that the maximum dc supply voltage does not
Through the process of supplying crystals for use with
Technical Note TN–24, Statek Corp.
Technical Note TN–7, Statek Corp.
E. Hafner, “The Piezoelectric Crystal Unit–Definitions and
D. Kemper, L. Rosine, “Quartz Crystals for Frequency
P. J. Ottowitz, “A Guide to Crystal Selection”, Electronic
D. Babin, “Designing Crystal Oscillators”, Machine Design ,
D. Babin, “Guidelines for Crystal Oscillator Design”,
NOTE: Motorola cannot recommend one supplier over another and in no way suggests
Motorola — Internet Address http://motorola.com
that this is a complete listing of crystal manufacturers.
Table 4. Partial List of Crystal Manufacturers
United States Crystal Corp.
Crystek Crystal
Fox Electronics
Statek Corp.
REF in
1
Figure 20. Parasitic Capacitances of the Amplifier
NOTE: Values are supplied by crystal manufacturer
Figure 19. Pierce Crystal Oscillator Circuit
* May be needed in certain cases. See text.
Figure 21. Equivalent Crystal Networks
(Search for resonators)
(parallel resonant crystal).
C1
2
C in
REF in
and C stray
1
1
C stray
R f
C2
C a
R1*
R e
R S
MC145200 MC145201
SYNTHESIZER
C out
FREQUENCY
X e
REF out
C O
L S
2
C S
REF out
2
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