MC74HC4046A
APPLICATION INFORMATION
The following information is a guide for approximate values of R1, R2, and C1. Figures 20, 21, and 22 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 = ∞
• Given f0
• Use f0 with
Figure 19 to
determine R1 and
C1.
(see Figure 24 for
characteristics of
the VCO operation)
R2 0 R
• Given f0 and fL
• Calculate fmin
fmin = f0−fL
• Determine values
of C1 and R2 from
Figure 21.
• Determine R1−C1
from Figure 22.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 22.
(see Figure 25 for
characteristics of
the VCO operation)
Phase Comparator 2
R2 = ∞
• Given fmax and f0
• Determine the
value of R1 and
C1 using Figure
20 and use Figure
22 to obtain 2fL
and then use this
to calculate fmin.
R2 0 R
• Given f0 and fL
• Calculate fmin
fmin = f0−fL
• Determine values
of C1 and R2 from
Figure 21.
• Determine R1−C1
from Figure 22.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 22.
(see Figure 25 for
characteristics of
the VCO operation)
Phase Comparator 3
R2 = ∞
• Given fmax and f0
• Determine the
value of R1 and
C1 using Figure
20 and Figure 22
to obtain 2fL and
then use this to
calculate fmin.
R2 0 R
• Given f0 and fL
• Calculate fmin:
fmin = f0−fL
• Determine values
of C1 and R2 from
Figure 21.
• Determine R1−C1
from Figure 22.
• Calculate value of
R1 from the value
of C1 and the
product of R1C1
from Figure 22.
(see Figure 25 for
characteristics of
the VCO operation)
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