February 1999
PRELIMINARY
ML6461
CCIR656 NTSC Video Encoder
GENERAL DESCRIPTION
The ML6461 is a multi-standard CCIR656 (4:2:2) video
(input) composite and S-video (outputs) encoder for NTSC
systems. It is designed to provide a low cost, single-chip
output interface for a variety of video applications
including set-top decoders, DVD players, and other YCrCb
to Y/C equipment.
The ML6461 accepts 8-bit YCrCb video in either CCIR656
or Square Pixel format and generates analog Y, C and CV
waveforms complete with Closed Caption encoding.
The ML6461 includes output analog reconstruction filters,
phase equalizer, and 6dB (2X gain) drivers. Gain scaling,
sync, and Y+C mixing are performed at the output of the
relevant 10-bit DAC, eliminating the gain mapping stages
that require additional DAC bits. The result is Y SNR and
granularity remain precisely the same as the source.
The ML6461 supports both master and slave timing
operations. S-Video and multiple composite signals can be
driven simultaneously into 75Ω loads.
FEATURES
s
s
s
s
s
Closed Caption VBI encoder for line 21 and 284
Handles SAV/EAV codes for CCIR656 Video
Single clock input: 27MHz CCIR656, 24.54MHz Sq. Pix.
Color subcarrier correction for overlay applications
Onboard analog 7th-order reconstruction filters and
6dB drivers with differential gain/phase of 0.5%/0.5º
Y, C, CV outputs drive both AC or DC coupled loads
Multiple 75Ω line drivers for two composite outputs,
channel modulator, and S-Video
2-wire serial control bus, or selectable presets for stand-
alone operation
Handles Japanese NTSC signals
s
s
s
s
BLOCK DIAGRAM
7
DVCC1
YCRCB0
DGNDI
8
14
DVCC2
15
DGND2
10 BIT
YDAC
1
AVCC1
2
AGND1
25
AVCC2
24
AGND2
YOUT
21
YCRCB1
20
YCRCB2
LUMA
BLANKING
DELAY
COMPEN-
SATION
UP
SAMPLER
LUMA
RECONSTRUCTION
FILTER
(FIR)
19
YCRCB3
7th ORDER
ANALOG
FILTER
WITH
GROUP DELAY
EQUALIZATION
6dB
27
CVOUT
+
Σ
+
6dB
26
COUT
INPUT Y/C DEMUX & CLOCK GENERATOR
18
YCRCB4
6dB
28
17
YCRCB5
NEGATIVE
SYNC DAC
TIMING
GENERATOR
(SAV/EAV)
CLOSED
CAPTIONING
POSITIVE
SYNC DAC
REFERENCE
GENERATOR
13
YCRCB6
12
YCRCB7
7th ORDER
ANALOG
FILTER
WITH
GROUP DELAY
EQUALIZATION
11
CLK
16
VSYNC
9
HSYNC
10
FIELD
CHROMA
BLANKING
BURST
INSERTION
5
SCLK
COLOR
SPACE
CONVERTER
UP
SAMPLER
CHROMA
BANDLIMIT
FILTER
MULTIPLYING
ACCUMULATOR
CHROMA
RECONSTRUCTION
FILTER
(FIR)
UP
SAMPLER
CDAC
22
SDATA
23
PRESET1
SERIAL
INTERFACE
OVERLAY
INTERFACE
PHASE
ACCUMULATOR
SUBCARRIER
GENERATION
Σ
8
PRESET0
PHERR
4
3
6
1
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
