MC74HC4046A Datasheet, PDF (14/15 Pages) ON Semiconductor – Phase-Locked Loop

MC74HC4046A
APPLICATION INFORMATION
The following information is a guide for approximate values of R1, R2, and C1. Figures 19, 20, and 21 should be used as
references as indicated below, also the values of R1, R2, and C1 should not violate the Maximum values indicated in the DC
ELECTRICAL CHARACTERISTICS tables.
Phase Comparator 1
R2 = ∞
R2 0 R
• Given f0
• Given f0 and fL
• Use f0 with Figure
19 to determine
R1 and C1.
(see Figure 23 for
characteristics of
the VCO operation)
• Calculate fmin
fmin = f0–fL
• Determine values
of C1 and R2 from
Figure 20.
• Determine R1–C1
from Figure 21.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 21.
(see Figure 24 for
characteristics of the
VCO operation)
Phase Comparator 2
R2 = ∞
R2 0 R
• Given fmax and f0
• Determine the
value of R1 and
C1 using Figure 19
and use Figure 21
to obtain 2fL and
then use this to
calculate fmin.
• Given f0 and fL
• Calculate fmin
fmin = f0–fL
• Determine values
of C1 and R2 from
Figure 20.
• Determine R1–C1
from Figure 21.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 21.
(see Figure 24 for
characteristics of the
VCO operation)
Phase Comparator 3
R2 = ∞
R2 0 R
• Given fmax and f0
• Determine the
value of R1 and
C1 using Figure 19
and Figure 21 to
obtain 2fL and
then use this to
calculate fmin.
• Given f0 and fL
• Calculate fmin:
fmin = f0–fL
• Determine values
of C1 and R2 from
Figure 20.
• Determine R1–C1
from Figure 21.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 21.
(see Figure 24 for
characteristics of the
VCO operation)
MOTOROLA
3–14
High–Speed CMOS Logic Data
DL129 — Rev 6