PRODUCT SPECIFICATION
TMC22071A
CVBS Bus Data Formats
The CVBS bus outputs a Genlock Reference Signal (GRS)
along with the 8-bit digital composite video data. The range
of output data versus video input voltage is illustrated in
Figure 7 where sync tip and blanking levels are controlled by
the digital backporch clamp of the TMC22071A. During
horizontal sync, the TMC22071A outputs field identifica-
tion, subcarrier frequency, and subcarrier phase information
on the CVBS bus.
Peak Chrominance
Peak Luminance
NTSC PAL
FEh
D2h
FFh
CFh
Field identification is output on CVBS
2-0
. The LSB,
CVBS
0
, will be LOW during odd fields and HIGH for even
fields. When NTSC operation is selected, CVBS
1-0
count
00,01,10,11 for fields 1 through 4 respectively. When PAL
operation is selected, CVBS
2-0
count 000, 001, 010, etc. to
111 for fields 1 through 8, respectively.
CVBS
3
indicates V-component inversion in PAL. It is HIGH
for NTSC lines (burst 135°) and LOW for PAL lines (burst
225°)
Subcarrier frequency is sent out in a 24-bit binary represen-
tation in six 4-bit nibbles on CVBS
3-0
. Subcarrier frequency
data, f
23-0
, is identical to the pre-programmed BSEED value
used in the TMC22071A to lock the subcarrier phase-locked
loop to the incoming subcarrier frequency.
Subcarrier phase,
F
23-0
, is also sent out in a 24-bit binary
representation in six 4-bit nibbles on CVBS
3-0
. Bit
F
23
is
the MSB.
Back Porch
Burst
Sync Tip
Blanking
3Ch
03h
40h
03h
65-22071-09
Figure 7. Output Data vs. Input Video Level
PXCK
0
GHSYNC
1
2
3
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
CVBS7:0
PIXEL
PIXEL
PIXEL
f
23:20
f
19:16
f
15:12
f
11:8
f
7:4
f
3:0
f
23:20
f
19:16
f
15:12
f
11:8
f
7:4
f
3:0
PIXEL
PIXEL
FREQUENCY
FIELD IDENTIFICATION
PHASE
65-22071-10
Figure 8. Genlock Reference Signal (GRS) Format
tPWHPX
PXCK
tDO
GHSYNC
tXL
LDV
tHO
CVBS7:0
tPWHPX
1/fPXCK
tXV
PIXEL 0
PIXEL 1
65-22071-11
Figure 9. CVBS Bus Video Data Format
11
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
