EL4585C Elantec Semiconductor, Inc. (acquired by Intersil), EL4585C Datasheet - Page 8

• Manufacturer Part Number: EL4585C
• Description: Horizontal Genlock, 8FSC
• 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 (1-5 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
EL4585C
Horizontal Genlock 8 F
OSC
T
T
1
desired operating frequency For our example
we will use 28 636MHz with an H-sync fre-
quency of 15 734kHz
works well) We choose 3 3 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
220pF for our example
2
2
1
1
2
F
C
C
2
v
2
L
)
)
1
LC
e
b
a
T
1
4
C
needed to produce F
Since
(C
T
C
(C
2
1
2
C
2
C
1
(28 636e6)
C
1
C
T
2
e
T
C
C
V
)
)
V
V
17pF (A trim cap may be
b
a
(C
(C
1
T
2
2
(3 3e
V
C
C
V
V
V
e
)
)
so we choose
23pF for our
b
OSC
6)
SC
V
e
9 4pF
2 5V
8
Note Use shielded inductors for optimum performance
LC VCO Component Values (Approximate)
Frequency
26 602
27 0
29 5
35 468
21 476
24 546
28 636
(MHz)
Typical Xtal VCO
Typical LC VCO
( H)
L1
3 3
3 3
2 7
2 2
4 7
3 9
3 3
(pF)
C1
22
21
22
16
26
22
17
(pF)
220
220
220
220
220
220
220
C2
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