ML6461
FUNCTIONAL DESCRIPTION
INTRODUCTION
The ML6461 is a single-chip NTSC video encoder for
generating analog composite (CV) and S-video (Y/C)
outputs from YCrCb digital inputs. The ML6461 is a mixed
signal processor optimizing SNR and distortion by
performing subcarrier generation, sync generation,
modulation and upsampling in the digital domain, while
performing mixing, reconstruction and gain scaling in the
analog domain. In particular, the Y channel requires no
digital scaling, eliminating the need for higher precision
digital solutions. All timing is based on an external clock
source either 27MHz for CCIR656 clock rate or
24.54MHz for square pixel clock rate.
Additionally, the ML6461 allows the inclusion of Closed
Captioning codes in the vertical blanking interval (VBI).
Both lines 21 and 284 support Closed Captioning.
Other special functions include: programmable polarity
and relative position of sync pulses, master and slave
modes of which includes the ability to handle ITU-R656-
compliant digital TV or ITU-R/SMPTE specifications,
chroma subcarrier phase and frequency adjustments from
external source; Japanese NTSC support; 100% color bars
processing; and internal 7
th
order reconstruction filters
with group delay equalization and 6dB line drivers for
direct TV output.
The ML6461 can be programmed and controlled via a
two-wire serial bus or preset modes. A summary of the
features of the ML6461 are listed in Table 1.
VIDEO STANDARDS SUPPORTED
The ML6461 supports NTSC only. The video standards
and clock rates are listed in Table 2.
DEVICE
FUNCTIONAL DESCRIPTION
Video Formats
Clock
Rates
DAC
Closed
Caption
Encoder
Macrovision
Reconstruction
Filter
75Ω
Ω
Cable
Driver
NTSC
PAL
CCIR656
Square
Pixel
ML6460
Yes. Input: 8-Bit
YCrCb digital
Outputs: Y, C,
and CV analog
Yes. Input: 8-Bit
YCrCb digital
Outputs: Y, C,
and CV analog
No
Yes
Yes
Yes.
10-bit
DAC
Yes.
10-bit
DAC
Yes
Yes
ML6461
No
Yes
Yes
Yes
No
Yes. 7th-order
Butterworth, with
group delay
equalization
Yes. 7th-order
Butterworth, with
group delay
equalization
Yes.
Yes.
Table 1. Video Encoder Functional Selection
INPUT
NTSC CCIR656
NTSC Square Pixel
CLOCK RATE
27 MHz
24.54 MHz
HORIZONTAL
LINES PER FRAME
525
525
PIXELS PER
HORIZONTAL LINE
858
780
Table 2: Video Standards and Clock Rates
MODE
Master Mode
External Slave Mode
Internal Slave Mode (SAV/EAV CCIR656)
VSYNC PIN
OUT
IN
OUT
HSYNC PIN
OUT
IN
OUT
FIELD PIN
IN/OUT
IN/OUT
IN/OUT
Table 3: Pin Assignments for Various Master/Slave Modes
6
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
