FS6011-02 AMI, FS6011-02 Datasheet - Page 3

• Manufacturer Part Number: FS6011-02
• Description: DIGITAL AUDIO/VIDEO CLOCK GENERATOR IC
• Manufacturer: AMI

www.DataSheet4U.com
July 1998
3.4
The VCXO provides a tunable, low-jitter frequency refer-
ence for the rest of the FS6011 system components.
Loading capacitance for the crystal is internal to the
FS6011. No external components (other than the reso-
nator itself) are required for operation of the VCXO.
The resonator loading capacitance is adjustable under
register control. This permits factory coarse tuning of in-
expensive resonators to the necessary precision for digi-
tal video applications. Refer to Section 4.6.
Continuous fine-tuning of the VCXO frequency is accom-
plished by varying the voltage on the XTUNE pin. The
total change (from one extreme to the other) in effective
loading capacitance is 1.5pF nominal.
The oscillator operates the crystal resonator in the paral-
lel-resonant mode. Crystal warping, or the “pulling” of the
crystal oscillation frequency, is accomplished by altering
the effective load capacitance presented to the crystal by
the oscillator circuit. The actual amount that changing the
load capacitance alters the oscillator frequency will be
dependent on the characteristics of the crystal as well as
the oscillator circuit itself.
Specifically, the motional capacitance of the crystal (usu-
ally referred to by crystal manufacturers as C
capacitance of the crystal (C
(C
the crystal in the oscillator circuit.
A simple formula to obtain the warping capability of a
crystal oscillator is:
where C
load capacitance.
A crystal with the following parameters is used. With C
0.02pF, C
coarse tuning range is
L
) of the oscillator determine the warping capability of
Oscillator (VCXO)
f
L1
Voltage-Controlled Crystal
f
0
and C
(
= 5pF, C
ppm
0
2
.
02
)
5
L2
are the two extremes of the applied
22
22
L1
2
.
66
= 10pF, and C
.
C
66
C
1
0
10
0
), and the load capacitance
C
5
C
L
2
L
10 6
10
2
C
L
1
C
L2
305
0
= 22.66pF, the
10
C
ppm
1
6
), the static
L
1
.
1
=
3
4.0
Table 2: Register Summary
BIT D[x]
10
11
12
13
14
0
1
2
3
4
5
6
7
8
9
Programming Information
ACLK Select (LSB)
ACLK Select
ACLK Select (MSB)
ACLK Off-Speed Mode
Bit = 0
Bit = 1
ACLK Speed Control
Bit = 0
Bit = 1
UCLK Select (LSB)
UCLK Select
UCLK Select (MSB)
CLK27 Select
Bit = 0
Bit = 1
Crystal Oscillator Coarse Tune (LSB)
Crystal Oscillator Coarse Tune
Crystal Oscillator Coarse Tune
Crystal Oscillator Coarse Tune (MSB)
VCXO Enable/Disable Control
Bit = 0
Bit = 1
Reserved (should be set to 0)
REGISTER BIT DESCRIPTION
Disable Off-Speed Mode
Enable Off-Speed Mode
Low Speed
High Speed
Selects VCXO Frequency
Selects UCLK Frequency
Disable VCXO Mode
Enable VCXO Mode
7.20.98