AK8850 Datasheet, PDF (22/99 Pages) Asahi Kasei Microsystems – NTSC Digital Video Decoder

ASAHI KASEI
[AK8850]
6. Functional Summary
6-1. Clock
1. Line Locked Clock mode:
An operating mode where the device operates using a clock synchronized with the Horizontal Sync signal for each line.
2. Frame Locked Clock mode:
The device operates using a clock synchronized with the Vertical Sync signal at each Frame.
3. Fixed Clock mode:
An external clock is used.
These clock modes are set with the Control 2 register. Since both the Line Locked and Frame Locked modes use an
input-signal synchronized clock, ITU-R BT.656* compatible output is available, although input signal quality may prevent
full ITU-R BT.656 compatibility.
6-2. Analog Interface
The AK8850 decodes NTSC-M compatible Composite video signals, S-video and Component signals. For CCIR625
systems, only the Component signal is used. Registers control setup selection.
6-3. Input Signals
The device accepts NTSC-M Composite,S-Video,, Composite ( Betacam,MII ) and 625 Component signals ( EBU N10 ).
Required input signal quality is as follows.
6-3-1 Composite ,S video input signal quality
Item
Input Range
Video signal input level
±6
Color Burst input level
± 10
Unit
Condition
dB Video signal should be input with -6dB level
dB (divided be a resistor), and through 0.1uF
capacitor.
6-3-2. Supporting signal characteristics for Composite and S-video signals
Item
Process
Lack of HSYNC
Running with self timing
Lack of VSYNC
Running with self-timing. When VSYNC is absent for two consecutive
cycles, the AK8850 identifies this as a “no-signal” state and sets the NSIG
pin High.
B/W Video Signal input
Set B/W mode using the register.
6-3-3. Component input signal
A Standard signal is applied in Component decode mode. Supported Component signal conditions are listed below.
Unit [mV]
Input video
Sync Luminance Luminance Luminance
U/V
Note
source
level (Setup Level) Level (max) (Range)
(Range)
BETACAM
(w/o Setup)
286
0
Luminance 100%
714
714
±504
U/V 100% Level
BETACAM
(with 7.5% Setup) ²⁸⁶
53.6
714
660.4
±350
Luminance 100%
U/V 75% Level
MII
(w/o Setup)
300
0
Luminance 100%
700
700
±350
U/V 100% Level
MII
(with Setup )
300
52.5
700
647.5
±243
Luminance 100%
U/V 75% Level
625 system
300
0
(EBU N10)
Luminance 100%
700
700
±350
U/V 100% Level
6-4. Analog Input Signal Processing
Input Selector : -60 dB ( inter-channel isolation )
PGA : 0 ~ 12 dB
AD converter : operates at 27 MHz
Line-lock or Frame-lock PLL clocks are used in normal operation.
Rev.0
22
2002/01