74hc7046a NXP Semiconductors, 74hc7046a Datasheet - Page 28

• Manufacturer Part Number: 74hc7046a
• Description: Phase-locked-loop With Lock Detector
• Manufacturer: NXP Semiconductors

Philips Semiconductors
December 1990
SUBJECT
VCO frequency
with extra
offset
Phase-locked-loop with lock detector
PHASE
COMPARATOR
PC1, PC2
PC1, PC2
DESIGN CONSIDERATIONS
VCO frequency characteristic
With R1 and R2 within the ranges 3 k
the characteristics of the VCO operation will be as shown in Fig. 24.
Selection of R1, R2 and C1
Given f
Calculate f
Obtain the values of C1 and R2 by using Fig.28.
Calculate the value of R1 from the value of C1 and the product R1C1.
0
Fig. 24 Frequency characteristic of VCO operating with offset:
and f
off
from the equation f
f
L
o
, determine the value of product R1C1 by using Fig.29.
= centre frequency; 2f
28
off
= f
o
L
= frequency lock range.
1.6f
R1 300 k
L
.
74HC/HCT7046A
3 k
Product specification
R2 300 k ,