EL4584C Elantec Semiconductor, Inc. (acquired by Intersil), EL4584C Datasheet - Page 9

• Manufacturer Part Number: EL4584C
• Description: Horizontal Genlock, 4FSC
• Manufacturer: Elantec Semiconductor, Inc. (acquired by Intersil)

Applications Information
Choosing External Components
1 To choose LC VCO components first pick the
2 Choose a reasonable inductor value (10– 20 H
3 Calculate C
F
C
4 From the varactor data sheet find C
5 C
6 Calculate C
C
then
C
For our example C
used for fine tuning ) Examples for each frequen-
cy using the internal divider follow
Typical Application
Horizontal genlock provides clock for an analog
to digital converter digitizing analog video
OSC
T
T
1
desired operating frequency For our example
we will use 14 31818 MHz with an H-sync fre-
quency of 15 734 kHz
works well) We choose 15 H
the desired lock voltage C
SMV1204-12 for example
C
e
e
e
2
2
e
4
(C
e
(C
should be about 10C
220 pF for our example
2
2
1
1
2
F
C
C
2
V
2
L
)
)
1
LC
e
a
b
T
1
4
needed to produce F
C
Since
T
C
(C
(C
2
1
2
C
2
C
1
(14 318e6)
1
C
C
T
2
e
C
C
T
V
)
14 pF (A trim cap may be
)
V
V
b
a
1
(C
(C
2
T
2
(15e
V
C
V
C
V
V
e
)
)
so we choose
23 pF for our
b
OSC
6)
V
e
8 2 pF
2 5V
9
Note Use shielded inductors for optimum performance
LC VCO Component Values (Approximate)
Frequency
(MHz)
13 301
13 5
14 75
17 734
10 738
12 273
14 318
Horizontal Genlock 4 F
Typical Xtal VCO
Typical LC VCO
Figure 10
Figure 11
( H)
L1
15
15
12
12
22
18
15
EL4584C
4584 – 18
(pF)
C1
18
17
18
10
20
17
14
(pF)
220
220
220
220
220
220
220
C2
4584 – 10
4584 – 11
SC